Old Shellac leaching problem

After listening to various opinions on this topic....both here and
elsewhere, it would appear that shellac is my friend :rolleyes: -
go figure. It would also appear that the staining coming up through
the (non-shellac) Bulls Eye primer may in fact NOT be shellac, since
shellac is not dissolved by waterbased products. argh.

Sooooo..... live and learn and experiment. Short of going backwards a
number of steps and sanding :( - would a couple of coats of
varathane form enough of a barrier against the alien leaching? I
could then prime on top of the varathane. (waterbased varathane in
fact is very acrylic paint friendly).

(thinking of switching to origami)

Thanks

M.

That's exactly what I did with the Zinsser's Bulls Eye Primer. After
the first coat had dried brown areas leached up through it. They look
like bad tea or tobacco stains. The same thing happened after the
second coat. When I put methyl hydrate on the stains, they became
wet and I was able to wipe off some brown, wet stain off the
surface.... but the main stain stayed.

The legs of the table - which were not sanded originally - did not
leach brown through and are ready to be painted with acrylic.

Maybe it's not shellac? If not, what else could it be?

Magda

"Magda" <[email protected]> wrote in message
news:[email protected]...
> Hello,
>
> My question pertains to stains, primers, sealers, etc.
>
> I "rescue" old pieces of furniture, spice racks, coat racks etc. and
> give them new life as painted works of art with acrylic artists
> paints. These are not antique pieces and most of them are discards
> from flea markets, etc. I have an old coffee table which I need to
> prime before painting it.
>
> It appears that this piece has a brownish shellac finish and through
> it's lifetime has had the top sanded down and subsequently pen and
> marker graffiti written on it.

> As a primer I applied a coat of Zinssers Primer Sealer Stain-Killer
> Bulls Eye 1-2-3 to the entire table. It has worked wonders on past
> projects - metal or wood. The sides and legs - which have not been
> previously sanded - turned out fine. The previously sanded top
> started to leach through brown stains in several places.

Shellac is dissolved by alcohol. Even old shellac is vulnerable. Putting
shellac on shellac just makes a mix of old and new. If that's not what you
want - old dirt in fresh shellac, get the old stuff cleaned off with alcohol
before you try again.

Have read suggestion to lightly spray dewaxed shellac and allow to
dry. Seems a thin coat doesn't dissolve the previous enough to let
the stain migrate up into the topcoat. Care in applying subsequent
coats is needed also. Worth a try.

On Mon, 21 Nov 2005 12:21:23 -0500, "Bruce Boyd"
<[email protected]> wrote:

>
>"Magda" <[email protected]> wrote in message
>news:[email protected]...
>> That's exactly what I did with the Zinsser's Bulls Eye Primer. After
>> the first coat had dried brown areas leached up through it. They look
>> like bad tea or tobacco stains. The same thing happened after the
>> second coat. When I put methyl hydrate on the stains, they became
>> wet and I was able to wipe off some brown, wet stain off the
>> surface.... but the main stain stayed.
>>
>> The legs of the table - which were not sanded originally - did not
>> leach brown through and are ready to be painted with acrylic.
>>
>> Maybe it's not shellac? If not, what else could it be?
>>
>> Magda
>>
>
>Try using shellac to cover one of the areas where the stain came through.
>After the shellac dries, try repriming that area and see if the stain comes
>back. I have always used shellac to prevent bleed-through and had good
>experience with it.
>
>Bruce
>

"Magda" <[email protected]> wrote in message
news:[email protected]...
> That's exactly what I did with the Zinsser's Bulls Eye Primer. After
> the first coat had dried brown areas leached up through it. They look
> like bad tea or tobacco stains. The same thing happened after the
> second coat. When I put methyl hydrate on the stains, they became
> wet and I was able to wipe off some brown, wet stain off the
> surface.... but the main stain stayed.
>
> The legs of the table - which were not sanded originally - did not
> leach brown through and are ready to be painted with acrylic.
>
> Maybe it's not shellac? If not, what else could it be?
>
> Magda
>

Try using shellac to cover one of the areas where the stain came through.
After the shellac dries, try repriming that area and see if the stain comes
back. I have always used shellac to prevent bleed-through and had good
experience with it.

Bruce

>As I will be undoubtedly coming across other similar old pieces, is
>there a way to seal, deactivate, prime or in some way neutralize the
>old shellac before starting to prime? Is there something I can do to
>this already primed piece which will eliminate the brown leaching?
>Would a coat or 3 of varethane be an effective sealer - after which I
>can put more primer on top of the varethane?


One of the beauties of shellac is that almost everyting adheres to it.
That's why it's often used as a sealer before overcoating. Overcoat it
with something (varnish, poly, even latex paint, whatever) that your
acrylics adhere to well, then paint on! One or two overcoats at most
should do it.

Regards.