thickening PVA to prevent veneer bleed through?

[David Zaret]

i have a figured sapele closet to build. for the veneering, normally i would use urea resin glue, with thickener, and dial in the thickener to prevent the glue from bleeding through the open pore veneer. for this job, i really want to use PVA if i can get away with it.

is there something i can add to the PVA that will thicken it? cornstarch?

i know i can buy titebond cold press which has crushed pecan shells, but that stuff is 1) hard to get, and 2) hard to stir. i was hoping to make my own small batches, thickened to my own consistency.

any ideas? thanks.

--- dz

[Paul F Franklin]

Perhaps you missed this recent thread: https://sawmillcreek.org/showthread.php?285369-If-only-Neanderthals-had-had-veneer-adhesive-like-this&highlight=veneer

[David Zaret]

i did indeed! and, i know and like joe, and will support him. good idea, i'll try his PVA. thanks.

[Mike Henderson]

If you use white glue, any bleed through can be washed off with a wet rag after the glue is set. You can't do that with Titebond.

Mike

[Kevin Jenness]

Have you tested your pva with the sapele to see if you really need a thickener? You might be able to get by with a minimal spread rate.

You might try sanding dust as a thickener.

I would just get a bucket of cold press and a paint stirring paddle. The filler does settle out pretty quickly. Turn the bucket over a couple of times before stirring.

Veneer Systems sells a thickened veneer glue that appears to be similar to the Titebond product https://veneersystems.com/product/mpa-veneer-5-gallons/

[David Zaret]

kevin, yeah i did, and it bled through badly. this is pommel sapele, and the glue wicked right through it. no big deal, i'll get some proper veneering PVA, or go back to UR (trying to avoid that for this job).

-- dz

[Jim Becker]

If you use white glue, any bleed through can be washed off with a wet rag after the glue is set. You can't do that with Titebond.


Would there still not be enough residue, at least in the porous surface to potentially affect finishing? I haven't had an issue with wiping glue off this way with species like maple and cherry, but with more porous/heavier grain, it's been more of an issue. For thin veneer, it may even saturate the wood which will noticeably affect finishing. Your thoughts?

[Robert Engel]

Coating the glue side of the veneer with shellac prevents bleed through.

[David Zaret]

Coating the glue side of the veneer with shellac prevents bleed through.


wouldn't that also affect adhesion?

[Mike Henderson]

Would there still not be enough residue, at least in the porous surface to potentially affect finishing? I haven't had an issue with wiping glue off this way with species like maple and cherry, but with more porous/heavier grain, it's been more of an issue. For thin veneer, it may even saturate the wood which will noticeably affect finishing. Your thoughts?

I've washed off white glue residue on veneer bleed through many times and never had any problem with the finish. You have to do a good job of washing it off, however.

It's kind of a trade-off. You need to wash hard but not enough that you affect the underlying glue bond. I've never had veneer come loose after washing the panel. If I did, I'd put it back in the veneer bag and press it. The glue between the veneer and substrate would still be there but it would have loosened. Pressing it until the glue sets again would fix the problem.

The difference between something like Titebond and white glue is that white glue can be washed off after it cures while Titebond can't. White glue provides a very good bond for veneer but if you were in a flood and the piece of furniture was immersed in water, all the veneer would come off. Otherwise, it lasts a long time.

I've used white glue on veneer quite a bit and have had no reports of delamination.

Mike

[Regarding glue showing after laying veneer - I've had problems with epoxy under veneer. When I removed the veneer tape (I was using the stuff with holes in it at the time) there was a pattern of dots where the tape was. The epoxy had come through the veneer but differentially between where the veneer tape was and the holes in the veneer tape. I had to do some finishing things to hide that but I was successful in hiding it.
Oh, and why use epoxy? Because it doesn't contain water and water causes certain veneers to expand, which can really cause problems with certain veneer designs.]