I'm hoping this starts a really good thread on spraying.
What has your experience shown you to be the best cut of shellac combined
with tip size when HVLP spraying? I Understand there are many other
factors, but I'm trying to narrow these down first. I've heard/read that
success varies widely with trying to spray shellac, but given the workpiece
(many nooks/crannies) that I want to spray. I *will* be dewaxing the
shellac which is advertised to be dewaxed (my own experience at work in this
decision).
Nailshooter, any advice?
jc
<[email protected]> wrote in message
news:3fe1f1a6-2eef-4418-82e5-7489a175a9a6@a21g2000yqc.googlegroups.com...
> Hi, Joe.
>
> I am of two minds on this, so I will split this up. First, spraying
> shellac isn't hard. Read everything Karl said, as there is good
> advice there.
>
<snip of stuff too good to snip>
Good luck on your project. Hope this helps.
>
> Robert
>
As always, great advice. Thank you all.
Printed and saved.
I'll post pics when finished, but if it's only of the top, you'll know why.
;-)
jc
<[email protected]> wrote in message
news:a5dd24d0-1ef0-436a-b742-6866d0f0979a@a21g2000yqc.googlegroups.com...
>
> That technique works well on my CAS (compressor powered) HVLP gun, but
> not well on the Fuji HVLP turbine. It may be the Fuji gun. I can
> change the trigger pressure just a bit to feather, but I usually have
> turbine pressure so low and the material thinned so much that the gun
> will spit and sputter if I don't give it the gas.
Argh! Good point Robert. I'm always shooting with a compressor rig so I
sometimes forget about the turbine rigs a lot of folks have. I don't own a
turbine rig so it doesn't come natural for me to consider that, and it
leaves me somewhat ignorant of the nuances of them. I'll have to remember
this particular nuance.
As well, in my applications, I try to avoid overthinning as much as I can,
to avoid die back. (Not so much an issue that most of the folks here would
have to deal with). I do have to thin more than I did in the high pressure
guns - it's just the nature of HVLP, but I've adapted all of my techniques
and developed all of my current techniques, such that they work with a
minimal addition of more thinners. Unless of course, I'm burning in - then
it's almost all thinner...
--
-Mike-
[email protected]
Hi, Joe.
I am of two minds on this, so I will split this up. First, spraying
shellac isn't hard. Read everything Karl said, as there is good
advice there.
To amplify his post a bit, spraying with an HVLP unit can be done.
But for me, I have found that I like it even thinner than Karl. I
like to thin it to just about water, work fast, and make multiple
coats. I get it down to about 1# or so and go from there. The beauty
of shellac is that one coat melts into the next, so there is no
disaster from bad coat like you get from varnish or poly.
So thin away, and DO NOT try to "hang" a coat. Spray quickly, and get
the surface evenly wet, with coats at a thin 2 mil or so. (For
reference, that's thinner than a paper dollar).
I thin shellac that much for two reasons. First being that I can
recoat in 30 minutes with no problems. So coat buildup is not really
an issue. Thin coats don't sag as long as you keep moving, and they
are easy to control.
Here is a tip I found on my own when spraying thinned finishes: spray
distilled water out of your gun onto a smooth surface like an brown
cardboard box. It is easy to see how your flow out will go, how fast
to move, and how to adjust your gun. It is good at mimicking the
first coat on sanded wood, too.
Next, mix up some finish and spray it onto a cardboard box that has a
smooth vinyl finish on it that protects a graphic, like a microwave
box, or any other box with a shiny finish. The shiny box will tell
all as to your spray ability.
OK, the second reason. Flying in the face of reason, shellac sprays
out better when thin, it dries more evenly, doesn't tend to blush, and
actually has a better pot life in the sprayer. It has something to do
with the amount of resin-to-solvent formula, and there is so little
resin in the overall thinned spray that it tends to NOT be as sticky
as a thicker cut, making it much to manage when spraying. It
shouldn't work that way, but it does. I spray enough material for me
to think the surface looks wet, then I move on.
The only downside I could see, is that using shellac in this manner
means multiple coats. But at 1/2 hour or so to recoat, you could get
all you needed in a base coat in just an hour and a half. If it's
just a seal coat, then a couple of coats will do it.
A word on HVLP spraying of any thinned finish. These of course are
generalities, but they work surprisingly well.
First, if it is drying before making contact, you are probably using
too much pressure, the wrong tip, both, or you are positioning the gun
too far from the surface. Start with the tip (actually, an aircap)
that approximates a 1.3 or 1.4mm tip.
Turn down the pressure, and let the small droplets come out, don't
think "spray". Let it sprinkle out, then turn up the pressure just
enough to come close to an atomized spray, but not quite. On your
four stage, it takes much less pressure than you think, and with
thinned material you may be blasting it to bits if you see it drying,
or a powder on the edges of your spray pattern.
Make sure you are the correct amount of distance from your target
surface. To get the correct amount of space, cut yourself a small
piece of something 8" and use that as a start point. Depending on the
material i am spraying, I have the gun as close as 6", and as far away
as ten. But they are all designed with 8" as their maximized
performance distance from the surface.
It is VERY easy to wander back an inch or three, <<and if you have the
pressure turned up to high, the bounce back will make you think you
need to move the gun back from the surface.>>
This is very important. Don't move the gun back. And if you do,
NEVER more than 10". If you have seen the way the spray pattern
develops from a gun after it leaves the tip, you will understand how
it takes the proper distance to develop a good spray pattern of the
droplets. The HVLP systems are easy to use if you understand the
mechanics behind them, and you must pay attention to them. Correct
droplet patterns don't develop under 6", and they degrade after 10".
So if you are getting plenty of material on the surface and there is
bounce back or drying powder, turn down the pressure. If that doesn't
work, close down the pattern a bit as well.
The last thoughts on shellac. Find yourself another can for your gun
and fill it about half way with your alcohol thinner. After you shoot
a coat, take the can off with the shellac in it, and seal it someway
(I use a piece of cardboard with something heavy on it) and put the
alcohol filled can on the gun. Shoot out a couple of ounces until you
get a fine watery spray, as shellac can be bad about clogging the ways
and tips. I hate spitting guns or poor patterns.
So, if you are still there, (I know, ask this guy what time it is and
he will tell you how to build a damn clock!) I have a question for
you.
Why would you use shellac on a gaming table? If you are thinking it
is some kind of superior bonding agent, it can be, but if you are
using NEW or very clean wood, there is no need for it. If you are
using it as sanding sealer and intend to sand to smooth the surfaces,
I get it. But as a sealer, there probably isn't a reason to do it.
Almost nothing in the finishing world sticks to itself like the same
finish. Whenever you can, avoid dissimilar finishes. If your wood is
dirty, possibly contaminated with chemicals, is reclaimed wood, or you
are refinishing, shellac is a splendid choice. It makes a great
bonding platform to build your finishes on since it will cover a
multitude of bad things that will foul your finish.
If you are going over this with poly, store your shellac and start
spraying your poly. No primer needed.
Something important to remember, especially on a hard use piece such
as a gaming table. The top coat will only be as good as the
substrate. Actually this is a hard, fast rule in all of painting and
finishing.
But in point, that means that the top coat will be softer than it
could be as the bottom coat (shellac) is soft and more flexible than a
poly or varnish used as a top coat. (These are kissing cousins -
don't fear the poly on a gaming table). A softer more flexible
substrate means less wear resistance on the top coat.
Worse, if one of your poker buddies dents the table somewhere and you
clean it up with a mild water based cleaner, you can cause blush or
discoloration due to shellac's poor water resistance. (Imagine the
shoe/boot wear on the base!) Now amp up your water based cleaner with
a good detergent base like 409, and you can LITERALLY peel the finish
off after a few good cleanings.
So if you have new, clean wood that has been carefully prepared, your
top coat should be your prime coat as well. Just put on the amount
indicated by the manufacturer for each coat, and follow the times set
out in the MSDS sheet.
Good luck on your project. Hope this helps.
Robert
On Wed, 6 Jan 2010 00:55:49 -0800 (PST), "[email protected]"
<[email protected]> wrote:
>Hi, Joe.
>
>I am of two minds on this, so I will split this up. First, spraying
>shellac isn't hard. Read everything Karl said, as there is good
>advice there.
>
>To amplify his post a bit, spraying with an HVLP unit can be done.
Snipped a hole lot of great info.
>Good luck on your project. Hope this helps.
>
>Robert
Thanks Robert for the taking the trouble to post such an in depth post
it has been filed for future reference.
Rgds,
Phil.
I've sprayed a bunch of lacquer but my experience didn't seem to help
me when it came to shellac. I only tried it once. I couldn't make it
work. It was a little warm and dry but not really hot but I just had
constant problems with powdering on the surface. Mostly the overspray
gave me trouble. Lacquer overspray alwasy seemd to flatten out anyway
but the shellac overspray was just dry. I think maybe some sort of
retarder might help or maybe less cut. The alco just drys so fricking
fast.
On Jan 5, 6:31=A0am, "Joe" <[email protected]> wrote:
> I'm hoping this starts a really good thread on spraying.
>
> What has your experience shown you to be the best cut of shellac combined
> with tip size when HVLP spraying? =A0I Understand there are many other
> factors, but I'm trying to narrow these down first. =A0I've heard/read th=
at
> success varies widely with trying to spray shellac, but given the workpie=
ce
> (many nooks/crannies) that I want to spray. =A0I *will* be dewaxing the
> shellac which is advertised to be dewaxed (my own experience at work in t=
his
> decision).
>
> Nailshooter, any advice?
>
> jc
<[email protected]> wrote in message
news:3fe1f1a6-2eef-4418-82e5-7489a175a9a6@a21g2000yqc.googlegroups.com...
>
> First, if it is drying before making contact, you are probably using
> too much pressure, the wrong tip, both, or you are positioning the gun
> too far from the surface. Start with the tip (actually, an aircap)
> that approximates a 1.3 or 1.4mm tip.
As I was reading Karl's last comments and the dialog that prompted them,
this was the very thought I had. Too much pressure is probably the most
common problem with people not accustomed to HVLP. When I switched over to
HVLP from the old siphon guns, I fought with this. It's almost like it
seems the pressure needs to be too low to atomize materials - but that's
where it needs to be. I went from shooting at around 40-50 psi, to around
13 psi. You could not have told me that this was the thing to do - I had to
ruin a couple of paint jobs and re-do them before I could learn...
He can compensate for the wrong tip size by adjusting the pressure, so if
the OP does not have a selection of tips for his gun, he's can still expect
a good finish. Especially for something as thin as this. I do agree that a
1.3 or 1.4 should a good tip size, but he's not sunk if he doesn't have
that.
>
> Turn down the pressure, and let the small droplets come out, don't
> think "spray". Let it sprinkle out, then turn up the pressure just
> enough to come close to an atomized spray, but not quite. On your
> four stage, it takes much less pressure than you think, and with
> thinned material you may be blasting it to bits if you see it drying,
> or a powder on the edges of your spray pattern.
My tip to people about adjusting pressure (and this works for some, not so
much for others)... Start with little or no pressure. Gradually increase
the pressure and listen intently to the gun. You will hear the point at
which the gun actually starts to atomize. The sound of the spray changes.
Stop there. Try it. It may not work for you, or it may. When I pick up a
gun that I've never shot with before, that's exactly what I do.
>
> Make sure you are the correct amount of distance from your target
> surface. To get the correct amount of space, cut yourself a small
> piece of something 8" and use that as a start point. Depending on the
> material i am spraying, I have the gun as close as 6", and as far away
> as ten. But they are all designed with 8" as their maximized
> performance distance from the surface.
Most people spray from too far away, trying not to get too much on and cause
a run. 6" seems so close so they back away. Keep it at 6" and vary your
speed across the object you're spraying. Keep your gun perpendicular to the
object as you move across. Watch your pattern as it goes down. Vary your
speed to keep an even wet film going down. Even and wet. As I've said
before here, imagine you're pulling a piece of plastic across the piece.
That's how your finish should go down.
Too far away, and as Robert says, you'll end up with dry edges and a look of
overspray. You really do not want to count on the stuff burning in, because
larger particles do not always burn in well. You can end up with an orange
peel or worse, very easily.
>
> It is VERY easy to wander back an inch or three, <<and if you have the
> pressure turned up to high, the bounce back will make you think you
> need to move the gun back from the surface.>>
>
> This is very important. Don't move the gun back. And if you do,
> NEVER more than 10". If you have seen the way the spray pattern
> develops from a gun after it leaves the tip, you will understand how
> it takes the proper distance to develop a good spray pattern of the
> droplets. The HVLP systems are easy to use if you understand the
> mechanics behind them, and you must pay attention to them. Correct
> droplet patterns don't develop under 6", and they degrade after 10".
Yup. Ergo my strong recommendations to practice on some scrap. Experiment
with different distances, different material delivery rates, different
pressures. You can quickly see the effects of each of these and you'll
recognize what causes the problems you're seeing.
>
> So if you are getting plenty of material on the surface and there is
> bounce back or drying powder, turn down the pressure. If that doesn't
> work, close down the pattern a bit as well.
Yup again. Practice on a piece of cardboard will demonstrate that you can
indeed get a pattern that is wet in the center and too dry around the edges.
One does not need to shoot a 10" pattern just because the gun is rated to do
it. There is after all, a reason for that pattern adjustment on a gun...
So one final thought, now that we're on the topic of adjustments. Don't
forget to learn to use your trigger. You don't really want to just pull
back full and go at it. If you're forced to blend into areas already shot,
you'll want to master the ability to increase and decrease trigger pressure
on the fly. Many people will try to twist the gun to blend, but at full
trigger that will end up with dry overspray in the farther areas. Instead,
learn to blend out by decreasing the delivery via the trigger.
--
-Mike-
[email protected]
"Swingman" <[email protected]> wrote in message
news:[email protected]...
>
> Yeah, Buddy! ... the book gets better! :)
>
Hell - I'm gonna want a signed copy of this book...
--
-Mike-
[email protected]
On Tue, 05 Jan 2010 14:31:50 GMT, the infamous "Joe" <[email protected]>
scrawled the following:
>I'm hoping this starts a really good thread on spraying.
Have that damned cat NEUTERED!
>What has your experience shown you to be the best cut of shellac combined
>with tip size when HVLP spraying? I Understand there are many other
>factors, but I'm trying to narrow these down first. I've heard/read that
>success varies widely with trying to spray shellac, but given the workpiece
>(many nooks/crannies) that I want to spray. I *will* be dewaxing the
>shellac which is advertised to be dewaxed (my own experience at work in this
>decision).
That's some pretty juicy stuff. Not having sprayed it, I'd suggest a
retarder (so the sprayer doesn't dry it before it hits) and a pretty
stiff mix to begin with, like a 5# cut (to reduce runs.) </swag>
--
Society is produced by our wants and government by our wickedness.
--Thomas Paine
On 1/5/2010 5:53 PM, Larry Jaques wrote:
> On Tue, 05 Jan 2010 15:22:03 -0600, the infamous Swingman
> <[email protected]> scrawled the following:
>
>> I just generally use the regular BullsEye amber 3 pound cut, thinned to
>> a 1 1/2 pound cut with isopropyl alcohol (depending upon the
>> temp/humidity) sprayed on for the final coat.
>
> Wow, thin cut. Do you do multiple -very- thin coats? I'm guessing
> the iso for a slower drying alcohol vs dna?
1 1/2# cut of shellac is pretty standard for spraying shellac, IME.
Here's how I view the rest of it, through my 'hands on' only experience:
Evaporation is obviously slower when the humidity is high due to the
higher moisture content in the air.
Blush is caused when the water in the thinner doesn't evaporate readily
and the sprayed surface dries.
So one method when spraying alcohol cut shellac in humid climates is to
either allow evaporation to go faster by spraying on days with low
humidity, or reduce the amount of water in the thinner (alcohol) itself
... mitigating, somewhat, the humidity induced slower evaporation as a
factor.
An anhydrous alcohol has a low(er) water content. I usually use a 99%
anhydrous isopropyl alcohol to cut shellac when spraying in this Gulf
Coast climate on really humid days.
As I mentioned earlier, a possible problem spraying with thin alcohol
cut shellac is the spray mist may dry before it actually hits the
surface of the project ... particularly true with cheaper HVLP guns
where you don't have a lot of tips available to fine tune the spray.
But you know, I really don't know that much about spraying and am not a
finishing expert by any means ... I do have a background in Chemistry,
so understand the dynamics and physical properties/reactions, but I'm a
trial and error kind of guy in the area, and try to use what I do know
to make changes until it works for me ...
IOW, YMMV may be an understatement in this case!
Robert needs to jump in here ...
--
www.e-woodshop.net
Last update: 10/22/08
KarlC@ (the obvious)
"Joe" <[email protected]> wrote in message
news:[email protected]...
>
> "Mike Marlow" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Swingman" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>>
>>> Yeah, Buddy! ... the book gets better! :)
>>>
>>
>> Hell - I'm gonna want a signed copy of this book...
>>
>> --
>>
>> -Mike-
>> [email protected]
>>
>
> Pretty sure 'shooter signs all of his emails, doesn't he??
>
> ;-)
>
> jc
>
>
Of course, now i realize that was *your* trigger tip, Mike, so please sign
the copy before you send it on to me..
best,
jc
On 1/6/2010 6:55 PM, Mike Marlow wrote:
> <[email protected]> wrote in message
> news:3fe1f1a6-2eef-4418-82e5-7489a175a9a6@a21g2000yqc.googlegroups.com...
>
>>
>> First, if it is drying before making contact, you are probably using
>> too much pressure, the wrong tip, both, or you are positioning the gun
>> too far from the surface. Start with the tip (actually, an aircap)
>> that approximates a 1.3 or 1.4mm tip.
>
> As I was reading Karl's last comments and the dialog that prompted them,
> this was the very thought I had. Too much pressure is probably the most
> common problem with people not accustomed to HVLP. When I switched over to
> HVLP from the old siphon guns, I fought with this. It's almost like it
> seems the pressure needs to be too low to atomize materials - but that's
> where it needs to be. I went from shooting at around 40-50 psi, to around
> 13 psi. You could not have told me that this was the thing to do - I had to
> ruin a couple of paint jobs and re-do them before I could learn...
>
> He can compensate for the wrong tip size by adjusting the pressure, so if
> the OP does not have a selection of tips for his gun, he's can still expect
> a good finish. Especially for something as thin as this. I do agree that a
> 1.3 or 1.4 should a good tip size, but he's not sunk if he doesn't have
> that.
>
>
>>
>> Turn down the pressure, and let the small droplets come out, don't
>> think "spray". Let it sprinkle out, then turn up the pressure just
>> enough to come close to an atomized spray, but not quite. On your
>> four stage, it takes much less pressure than you think, and with
>> thinned material you may be blasting it to bits if you see it drying,
>> or a powder on the edges of your spray pattern.
>
> My tip to people about adjusting pressure (and this works for some, not so
> much for others)... Start with little or no pressure. Gradually increase
> the pressure and listen intently to the gun. You will hear the point at
> which the gun actually starts to atomize. The sound of the spray changes.
> Stop there. Try it. It may not work for you, or it may. When I pick up a
> gun that I've never shot with before, that's exactly what I do.
>
>
>>
>> Make sure you are the correct amount of distance from your target
>> surface. To get the correct amount of space, cut yourself a small
>> piece of something 8" and use that as a start point. Depending on the
>> material i am spraying, I have the gun as close as 6", and as far away
>> as ten. But they are all designed with 8" as their maximized
>> performance distance from the surface.
>
> Most people spray from too far away, trying not to get too much on and cause
> a run. 6" seems so close so they back away. Keep it at 6" and vary your
> speed across the object you're spraying. Keep your gun perpendicular to the
> object as you move across. Watch your pattern as it goes down. Vary your
> speed to keep an even wet film going down. Even and wet. As I've said
> before here, imagine you're pulling a piece of plastic across the piece.
> That's how your finish should go down.
>
> Too far away, and as Robert says, you'll end up with dry edges and a look of
> overspray. You really do not want to count on the stuff burning in, because
> larger particles do not always burn in well. You can end up with an orange
> peel or worse, very easily.
>
>>
>> It is VERY easy to wander back an inch or three,<<and if you have the
>> pressure turned up to high, the bounce back will make you think you
>> need to move the gun back from the surface.>>
>>
>> This is very important. Don't move the gun back. And if you do,
>> NEVER more than 10". If you have seen the way the spray pattern
>> develops from a gun after it leaves the tip, you will understand how
>> it takes the proper distance to develop a good spray pattern of the
>> droplets. The HVLP systems are easy to use if you understand the
>> mechanics behind them, and you must pay attention to them. Correct
>> droplet patterns don't develop under 6", and they degrade after 10".
>
> Yup. Ergo my strong recommendations to practice on some scrap. Experiment
> with different distances, different material delivery rates, different
> pressures. You can quickly see the effects of each of these and you'll
> recognize what causes the problems you're seeing.
>
>>
>> So if you are getting plenty of material on the surface and there is
>> bounce back or drying powder, turn down the pressure. If that doesn't
>> work, close down the pattern a bit as well.
>
> Yup again. Practice on a piece of cardboard will demonstrate that you can
> indeed get a pattern that is wet in the center and too dry around the edges.
> One does not need to shoot a 10" pattern just because the gun is rated to do
> it. There is after all, a reason for that pattern adjustment on a gun...
>
>
> So one final thought, now that we're on the topic of adjustments. Don't
> forget to learn to use your trigger. You don't really want to just pull
> back full and go at it. If you're forced to blend into areas already shot,
> you'll want to master the ability to increase and decrease trigger pressure
> on the fly. Many people will try to twist the gun to blend, but at full
> trigger that will end up with dry overspray in the farther areas. Instead,
> learn to blend out by decreasing the delivery via the trigger.
Yeah, Buddy! ... the book gets better! :)
--
www.e-woodshop.net
Last update: 10/22/08
KarlC@ (the obvious)
"SonomaProducts.com" <[email protected]> wrote in message
news:[email protected]...
I've sprayed a bunch of lacquer but my experience didn't seem to help
me when it came to shellac. I only tried it once. I couldn't make it
work. It was a little warm and dry but not really hot but I just had
constant problems with powdering on the surface. Mostly the overspray
gave me trouble. Lacquer overspray alwasy seemd to flatten out anyway
but the shellac overspray was just dry. I think maybe some sort of
retarder might help or maybe less cut. The alco just drys so fricking
fast.
That's what I'm afraid of (fast dry and overspray). I've mixed a 1/2# cut
but haven't tried it yet.
I don't like to think this way, but it's a game table base (pedestal), so
maybe the state of mind of the people who do get to see it will keep them
from being too critical... (I hope).
jc
On Jan 5, 6:31 am, "Joe" <[email protected]> wrote:
> I'm hoping this starts a really good thread on spraying.
>
> What has your experience shown you to be the best cut of shellac combined
> with tip size when HVLP spraying? I Understand there are many other
> factors, but I'm trying to narrow these down first. I've heard/read that
> success varies widely with trying to spray shellac, but given the
> workpiece
> (many nooks/crannies) that I want to spray. I *will* be dewaxing the
> shellac which is advertised to be dewaxed (my own experience at work in
> this
> decision).
>
> Nailshooter, any advice?
>
> jc
"Mike Marlow" <[email protected]> wrote in message
news:[email protected]...
>
> <[email protected]> wrote in message
> news:3fe1f1a6-2eef-4418-82e5-7489a175a9a6@a21g2000yqc.googlegroups.com...
>
>>
>> First, if it is drying before making contact, you are probably using
>> too much pressure, the wrong tip, both, or you are positioning the gun
>> too far from the surface. Start with the tip (actually, an aircap)
>> that approximates a 1.3 or 1.4mm tip.
>
> As I was reading Karl's last comments and the dialog that prompted them,
> this was the very thought I had. Too much pressure is probably the most
> common problem with people not accustomed to HVLP. When I switched over
> to HVLP from the old siphon guns, I fought with this. It's almost like it
> seems the pressure needs to be too low to atomize materials - but that's
> where it needs to be. I went from shooting at around 40-50 psi, to around
> 13 psi. You could not have told me that this was the thing to do - I had
> to ruin a couple of paint jobs and re-do them before I could learn...
>
> He can compensate for the wrong tip size by adjusting the pressure, so if
> the OP does not have a selection of tips for his gun, he's can still
> expect a good finish. Especially for something as thin as this. I do
> agree that a 1.3 or 1.4 should a good tip size, but he's not sunk if he
> doesn't have that.
>
>
>>
>> Turn down the pressure, and let the small droplets come out, don't
>> think "spray". Let it sprinkle out, then turn up the pressure just
>> enough to come close to an atomized spray, but not quite. On your
>> four stage, it takes much less pressure than you think, and with
>> thinned material you may be blasting it to bits if you see it drying,
>> or a powder on the edges of your spray pattern.
>
> My tip to people about adjusting pressure (and this works for some, not so
> much for others)... Start with little or no pressure. Gradually increase
> the pressure and listen intently to the gun. You will hear the point at
> which the gun actually starts to atomize. The sound of the spray changes.
> Stop there. Try it. It may not work for you, or it may. When I pick up
> a gun that I've never shot with before, that's exactly what I do.
>
>
>>
>> Make sure you are the correct amount of distance from your target
>> surface. To get the correct amount of space, cut yourself a small
>> piece of something 8" and use that as a start point. Depending on the
>> material i am spraying, I have the gun as close as 6", and as far away
>> as ten. But they are all designed with 8" as their maximized
>> performance distance from the surface.
>
> Most people spray from too far away, trying not to get too much on and
> cause a run. 6" seems so close so they back away. Keep it at 6" and vary
> your speed across the object you're spraying. Keep your gun perpendicular
> to the object as you move across. Watch your pattern as it goes down.
> Vary your speed to keep an even wet film going down. Even and wet. As
> I've said before here, imagine you're pulling a piece of plastic across
> the piece. That's how your finish should go down.
>
> Too far away, and as Robert says, you'll end up with dry edges and a look
> of overspray. You really do not want to count on the stuff burning in,
> because larger particles do not always burn in well. You can end up with
> an orange peel or worse, very easily.
>
>>
>> It is VERY easy to wander back an inch or three, <<and if you have the
>> pressure turned up to high, the bounce back will make you think you
>> need to move the gun back from the surface.>>
>>
>> This is very important. Don't move the gun back. And if you do,
>> NEVER more than 10". If you have seen the way the spray pattern
>> develops from a gun after it leaves the tip, you will understand how
>> it takes the proper distance to develop a good spray pattern of the
>> droplets. The HVLP systems are easy to use if you understand the
>> mechanics behind them, and you must pay attention to them. Correct
>> droplet patterns don't develop under 6", and they degrade after 10".
>
> Yup. Ergo my strong recommendations to practice on some scrap.
> Experiment with different distances, different material delivery rates,
> different pressures. You can quickly see the effects of each of these and
> you'll recognize what causes the problems you're seeing.
>
>>
>> So if you are getting plenty of material on the surface and there is
>> bounce back or drying powder, turn down the pressure. If that doesn't
>> work, close down the pattern a bit as well.
>
> Yup again. Practice on a piece of cardboard will demonstrate that you can
> indeed get a pattern that is wet in the center and too dry around the
> edges. One does not need to shoot a 10" pattern just because the gun is
> rated to do it. There is after all, a reason for that pattern adjustment
> on a gun...
>
>
> So one final thought, now that we're on the topic of adjustments. Don't
> forget to learn to use your trigger. You don't really want to just pull
> back full and go at it. If you're forced to blend into areas already
> shot, you'll want to master the ability to increase and decrease trigger
> pressure on the fly. Many people will try to twist the gun to blend, but
> at full trigger that will end up with dry overspray in the farther areas.
> Instead, learn to blend out by decreasing the delivery via the trigger.
>
>
> --
>
> -Mike-
> [email protected]
>
Mike, good points. I *do* have a full selection of tips to choose from,
but that was just causing me to pre-second guess. As soon as this shellac
finishes dissolving, I'm going to put this info to good use.
jc
On 1/5/2010 2:22 PM, Joe wrote:
> "SonomaProducts.com"<[email protected]> wrote in message
> news:[email protected]...
> I've sprayed a bunch of lacquer but my experience didn't seem to help
> me when it came to shellac. I only tried it once. I couldn't make it
> work. It was a little warm and dry but not really hot but I just had
> constant problems with powdering on the surface. Mostly the overspray
> gave me trouble. Lacquer overspray alwasy seemd to flatten out anyway
> but the shellac overspray was just dry. I think maybe some sort of
> retarder might help or maybe less cut. The alco just drys so fricking
> fast.
>
> That's what I'm afraid of (fast dry and overspray). I've mixed a 1/2# cut
> but haven't tried it yet.
>
> I don't like to think this way, but it's a game table base (pedestal), so
> maybe the state of mind of the people who do get to see it will keep them
> from being too critical... (I hope).
Shellac is about the only finish I use, and I always spray it.
With an HVLP system overspray is not a problem, IME.
If you are not planning on using anything but shellac, buy the three
pound cut and thin it down to 1 1/2 with alcohol (I prefer to use this
cut when spraying, but YMMV) ... experiment.
3 pound cut is what you get out of the can for the standard, althouugh
I've seen 4 and 5 pound cut at paint stores, and the "sanding sealer",
out of the can should be a 2 pound cut.
You really don't need the dewaxed if shellac is all you're using ... the
dewaxed being essential for compatibility with lacquer, poly and other
top coat finishes added post shellac application.
The Zinnser sealer is dewaxed and works well when sprayed and can indeed
be used as the finish coat.
I just generally use the regular BullsEye amber 3 pound cut, thinned to
a 1 1/2 pound cut with isopropyl alcohol (depending upon the
temp/humidity) sprayed on for the final coat.
I find I have better application on extremely high humidity days with
isopropyl alcohol, but the Borg denatured works fine 99% of the time.
IME, with humidity, what you're worrying about is blush.
With isopropyl alcohol so cutting you need to pay particular attention
to the shellac drying before it hits the surface. If that is a problem,
simply cut your material flow down a bit and spray closer to the work
(with HVLP).
Spraying shellac is not that difficult, as a matter of fact, it is easy
and forgiving with an off the shelf, $100 HVLP unit. A couple of minutes
with a scrap piece to make sure material flow and distance is right, and
spray on.
www.e-woodshop.net
Last update: 10/22/08
KarlC@ (the obvious)
On 1/6/2010 7:07 AM, Larry Jaques wrote:
> I'm going to print out this entire post and hang it with my gun for
> enlightenment the next time I spray.
>
> You condensed into one post what Andy Charron took 2 entire books to
> say, Robert. Goodonya. (I have his _Spray Finishing_ and _Water
> Based Finishes_ books.)
Robert _is_ writing a book ... he just doesn't know it. :)
I've saved ALL his finishing posts for a number of years now.
--
www.e-woodshop.net
Last update: 10/22/08
KarlC@ (the obvious)
On Jan 6, 6:55 pm, "Mike Marlow" <[email protected]> wrote:
> Too much pressure is probably the most
> common problem with people not accustomed to HVLP. When I switched over to
> HVLP from the old siphon guns, I fought with this. It's almost like it
> seems the pressure needs to be too low to atomize materials - but that's
> where it needs to be. I went from shooting at around 40-50 psi, to around
> 13 psi. You could not have told me that this was the thing to do - I had to
> ruin a couple of paint jobs and re-do them before I could learn...
I was right there with you. I didn't ruin anything, but on the other
hand I burned up (literally) a couple of hundred bucks of material
before I understood what I was doing, and probably at least half that
much again to get it right. I couldn't get it through my head the
differences in high pressure and HVLP. Maybe over the years I inhaled
too much solvent... wait, I didn't inhale....
For anyone following along, the difference is this: When you shoot
high pressure guns, you atomize the paint into near particulates to
shoot a fine spray. This is what we all did for years. Using long
oil finishes such as enamels, varnishes, and even polyurethane, these
guns worked well since they could blast the finishes into the tiny,
fine droplets to be easily applied. And since they were long oil
finishes that had long lay out times, if you got an even coat on, it
dried evenly because it could take an hour or better just to tack.
The key to HVLP though, is good thinning and paying attention to the
environment you are in, namely watching temps and humidity. I find on
our fall days here in south Texas, that my mixes are different in the
morning and afternoon, mostly because of temperature differential.
Warmer weather means less thinning, especially on solvent based
finishes. Most finishes are made to be sprayed these days with modern
spray equipment in mind, so atomizing the coating isn't necessary as
it was in the old high pressure days. However, to get the finishes to
lay out properly, the must be thinned to the correct consistency to
spray, and then applied properly.
In the old high pressure days, we thinned just to get the material out
of the gun reliably. In the HVLP days, we thin to get it to the
surface with just enough time to lay out properly. HUGE difference.
> My tip to people about adjusting pressure (and this works for some, not so
> much for others)... Start with little or no pressure. Gradually increase
> the pressure and listen intently to the gun. You will hear the point at
> which the gun actually starts to atomize. The sound of the spray changes.
> Stop there. Try it. It may not work for you, or it may. When I pick up a
> gun that I've never shot with before, that's exactly what I do.
I do exactly the same thing. Except I am a bit more impatient. I do
crack them open a bit to get started. But I also do the same thing
with the pattern nozzle. I like to bring them up together, opening
and shooting a bit at a time.
> Most people spray from too far away, trying not to get too much on and cause
> a run. 6" seems so close so they back away. Keep it at 6" and vary your
> speed across the object you're spraying. Keep your gun perpendicular to the
> object as you move across. Watch your pattern as it goes down.
I noticed this when cleaning out one of my guns late at night in front
of my halogen stand lights. This is a neat trick to find out exactly
where the sweet spot is on your gun, and to understand the halo
pattern HVLP guns put out. I was shooting gun wash thinner out of the
gun and had a light off to one side. I noticed that made a really
cool looking pattern. By turning down the pressure down to very low,
I could see exactly how the engineered output of the gun was supposed
to look. In front of the aircap at about 8" ( hey - the manufacturer
wasn't lying!!) the pattern actually crossed itself and made this neat
looking pointed oval design. The design was caused by the way the
aircap horns have their airstream aimed, thus propelling the material
into the proper pattern.
Pretty neat, eh? Although it makes perfect sense, I found that
totally by mistake. I never noticed that on my high pressure guns
since the atomized cloud made it so much less obvious. So I put other
aircaps on my guns, and put water in the can instead of thinner, and
tested them out in a rake light as well. Same thing. The most
obvious was when I got to the 1mm tip. It just misted out the
material in a gently spray that made a pretty overlap. Nicest
coverage/sweet spot on my Fuji gun: 8" - 9".
I thought that was a neat way to find the sweet spot on the gun's
output. But more importantly, it reinforces the need to pay attention
to the gun distance to the target. These HVLP machines are surprising
sophisticated.
> So one final thought, now that we're on the topic of adjustments. Don't
> forget to learn to use your trigger. You don't really want to just pull
> back full and go at it. If you're forced to blend into areas already shot,
> you'll want to master the ability to increase and decrease trigger pressure
> on the fly. Many people will try to twist the gun to blend, but at full
> trigger that will end up with dry overspray in the farther areas. Instead,
> learn to blend out by decreasing the delivery via the trigger.
That technique works well on my CAS (compressor powered) HVLP gun, but
not well on the Fuji HVLP turbine. It may be the Fuji gun. I can
change the trigger pressure just a bit to feather, but I usually have
turbine pressure so low and the material thinned so much that the gun
will spit and sputter if I don't give it the gas.
Most of the stuff I shoot is so hot that I don't get a big chance to
feather in a spray stroke anyway. If I catch a missed overlap two
strokes down, with the lacquer or fast dry enamels thinned the way I
do it, it is too late. What I wind up doing is laying a top coat down
on the problem area up to the adjoining surfaces of a thin wet mist
coat, thinned to about 50% or more to let the solvent take care of the
overlap mistakes.
Good post, Mike.
Robert
On Wed, 06 Jan 2010 18:39:58 GMT, the infamous "Joe" <[email protected]>
scrawled the following:
>
><[email protected]> wrote in message
>news:3fe1f1a6-2eef-4418-82e5-7489a175a9a6@a21g2000yqc.googlegroups.com...
>> Hi, Joe.
>>
>> I am of two minds on this, so I will split this up. First, spraying
>> shellac isn't hard. Read everything Karl said, as there is good
>> advice there.
>>
>
><snip of stuff too good to snip>
>
> Good luck on your project. Hope this helps.
>>
>> Robert
>>
>
>As always, great advice. Thank you all.
>
>Printed and saved.
>
>I'll post pics when finished, but if it's only of the top, you'll know why.
>;-)
That's the Wreck DEFEATIST Spirit, Joe! Carry on.
--
We rightly care about the environment. But our neurotic obsession
with carbon betrays an inability to distinguish between pollution
and the stuff of life itself. --Bret Stephens, WSJ 1/5/10
On Tue, 05 Jan 2010 15:22:03 -0600, the infamous Swingman
<[email protected]> scrawled the following:
>I just generally use the regular BullsEye amber 3 pound cut, thinned to
>a 1 1/2 pound cut with isopropyl alcohol (depending upon the
>temp/humidity) sprayed on for the final coat.
Wow, thin cut. Do you do multiple -very- thin coats? I'm guessing
the iso for a slower drying alcohol vs dna?
--
Society is produced by our wants and government by our wickedness.
--Thomas Paine
"Mike Marlow" <[email protected]> wrote in message
news:[email protected]...
>
> "Swingman" <[email protected]> wrote in message
> news:[email protected]...
>
>>
>> Yeah, Buddy! ... the book gets better! :)
>>
>
> Hell - I'm gonna want a signed copy of this book...
>
> --
>
> -Mike-
> [email protected]
>
Pretty sure 'shooter signs all of his emails, doesn't he??
;-)
jc
"Swingman" <[email protected]> wrote in message
news:[email protected]...
> On 1/5/2010 2:22 PM, Joe wrote:
>> "SonomaProducts.com"<[email protected]> wrote in message
>> news:[email protected]...
>> I've sprayed a bunch of lacquer but my experience didn't seem to help
>> me when it came to shellac. I only tried it once. I couldn't make it
>> work. It was a little warm and dry but not really hot but I just had
>> constant problems with powdering on the surface. Mostly the overspray
>> gave me trouble. Lacquer overspray alwasy seemd to flatten out anyway
>> but the shellac overspray was just dry. I think maybe some sort of
>> retarder might help or maybe less cut. The alco just drys so fricking
>> fast.
>>
>> That's what I'm afraid of (fast dry and overspray). I've mixed a 1/2#
>> cut
>> but haven't tried it yet.
>>
>> I don't like to think this way, but it's a game table base (pedestal), so
>> maybe the state of mind of the people who do get to see it will keep them
>> from being too critical... (I hope).
>
> Shellac is about the only finish I use, and I always spray it.
>
> With an HVLP system overspray is not a problem, IME.
that's good. I have an Apollo 4-stage
>
> If you are not planning on using anything but shellac, buy the three pound
> cut and thin it down to 1 1/2 with alcohol (I prefer to use this cut when
> spraying, but YMMV) ... experiment.
I'm starting from flakes and mixing it to 1 1/2#, so still good....
>
> 3 pound cut is what you get out of the can for the standard, althouugh
> I've seen 4 and 5 pound cut at paint stores, and the "sanding sealer", out
> of the can should be a 2 pound cut.
>
> You really don't need the dewaxed if shellac is all you're using ... the
> dewaxed being essential for compatibility with lacquer, poly and other top
> coat finishes added post shellac application.
This is going to have a top coat, since it's a game table and there's bound
to be alcohol present at *some* point :-)
> The Zinnser sealer is dewaxed and works well when sprayed and can indeed
> be used as the finish coat.
>
> I just generally use the regular BullsEye amber 3 pound cut, thinned to a
> 1 1/2 pound cut with isopropyl alcohol (depending upon the temp/humidity)
> sprayed on for the final coat.
>
> I find I have better application on extremely high humidity days with
> isopropyl alcohol, but the Borg denatured works fine 99% of the time.
I think I'm out of luck with high humidity. Still frickin freezin (I blame
robatoy) here.
using borg den'ed
>
> IME, with humidity, what you're worrying about is blush.
>
> With isopropyl alcohol so cutting you need to pay particular attention to
> the shellac drying before it hits the surface. If that is a problem,
> simply cut your material flow down a bit and spray closer to the work
> (with HVLP).
good advice
> Spraying shellac is not that difficult, as a matter of fact, it is easy
> and forgiving with an off the shelf, $100 HVLP unit. A couple of minutes
> with a scrap piece to make sure material flow and distance is right, and
> spray on.
Thanks Karl
>
>
> www.e-woodshop.net
> Last update: 10/22/08
> KarlC@ (the obvious)
On Wed, 6 Jan 2010 22:58:13 -0500, the infamous "Mike Marlow"
<[email protected]> scrawled the following:
>
>"Swingman" <[email protected]> wrote in message
>news:[email protected]...
>
>>
>> Yeah, Buddy! ... the book gets better! :)
>>
>
>Hell - I'm gonna want a signed copy of this book...
Ditto here. Hey, Naily, whatcha say? When's the pub date?
--
We rightly care about the environment. But our neurotic obsession
with carbon betrays an inability to distinguish between pollution
and the stuff of life itself. --Bret Stephens, WSJ 1/5/10
On Wed, 6 Jan 2010 00:55:49 -0800 (PST), the infamous
"[email protected]" <[email protected]> scrawled the
following:
>Hi, Joe.
>
>I am of two minds on this, so I will split this up. First, spraying
>shellac isn't hard. Read everything Karl said, as there is good
>advice there.
>
>To amplify his post a bit, spraying with an HVLP unit can be done.
>But for me, I have found that I like it even thinner than Karl. I
>like to thin it to just about water, work fast, and make multiple
>coats. I get it down to about 1# or so and go from there. The beauty
>of shellac is that one coat melts into the next, so there is no
>disaster from bad coat like you get from varnish or poly.
>
>So thin away, and DO NOT try to "hang" a coat. Spray quickly, and get
>the surface evenly wet, with coats at a thin 2 mil or so. (For
>reference, that's thinner than a paper dollar).
>
>I thin shellac that much for two reasons. First being that I can
>recoat in 30 minutes with no problems. So coat buildup is not really
>an issue. Thin coats don't sag as long as you keep moving, and they
>are easy to control.
>
>Here is a tip I found on my own when spraying thinned finishes: spray
>distilled water out of your gun onto a smooth surface like an brown
>cardboard box. It is easy to see how your flow out will go, how fast
>to move, and how to adjust your gun. It is good at mimicking the
>first coat on sanded wood, too.
>
>Next, mix up some finish and spray it onto a cardboard box that has a
>smooth vinyl finish on it that protects a graphic, like a microwave
>box, or any other box with a shiny finish. The shiny box will tell
>all as to your spray ability.
--snip-- Excellent, Naily.
I'm going to print out this entire post and hang it with my gun for
enlightenment the next time I spray.
You condensed into one post what Andy Charron took 2 entire books to
say, Robert. Goodonya. (I have his _Spray Finishing_ and _Water
Based Finishes_ books.)
--
We rightly care about the environment. But our neurotic obsession
with carbon betrays an inability to distinguish between pollution
and the stuff of life itself. --Bret Stephens, WSJ 1/5/10