I make 1/16" shop sawn veneer, assemble panels in the usual with with veneer tape, and then glue it onto plywood, MDF, or particle board cores in a vacuum bag. By the time the panels are finish sanded I would estimate that the veneer is 0.050 - 0.060" thick. I've used Weldwood Plastic Resin Glue almost exclusively for at least years, but I also have used epoxy when I glued some to one side of Melamine after sanding off the coating. The MC of both the veneer and cores has always been between about 6% and 9% (30 - 55% RH), Winter to Summer in my heated, dehumidified basement shop. The temp. has always been at least 70F and I leave the panels in the press for 13 - 14 hours at roughly 20" Hg.

About 3 years ago I built a vanity for my own house, using ash over the sanded Melamine with epoxy, and on MDF with PRG. After a year I noticed one of the veneer seams on the Melamine panel had split opened a little. That was in the middle of Winter. The next Summer I couldn't see it. The next Winter I could see it again, plus a couple more. This Winter I see a split seam on the two doors of the cabinet, which were done with PRG on MDF. All of these panels are about 32" tall with the veneer running horizontally, so 32" of cross grain if you will. My house gets down to the same 30% RH in the Winter as my shop, and goes as high as 75% sometimes in the Summer unless the AC is on.

None of the seams on that cabinet were preglued when I taped up the veneer panels. I built a storage cabinet for the same bathroom 2 years ago, using more ash veneer over MDF with PRG. On those panels I did preglue the seams with TB II or III when I made the veneer panels. No seams have split open on those doors.

Last year I started rehabbing my kitchen using, you guessed it, more ash veneer, this time glued with PRG on composite panels - plywood core with particle board on both sides. I preglued all of the seams with TB II on the veneer panels before gluing them to the cores. Earlier this week I noticed a few of those seams starting to split.

So I've seen seam splits on particle board and MDF cores glued with both epoxy and PRG. I don't recall ever seeing a split seam with plywood cores, thankfully, because I have quite a few customer projects out there. I'm sure I would have heard; who knows, maybe the phone will ring any day. Most of the projects I've sold have used maple, white oak, and walnut veneer; none with ash.

I'm working on another section of my kitchen rehab this Winter using the same materials and process, except for a few panels that I substituted poplar plywood for the substrate just for comparison. I have always used the recommended spread rate for PRG of 1 lb of resin per 40 sq. ft of substrate, regardless of which type, but after seeing the seam splits I've increased it to 1 lb/35 sq. ft and it's noticeably heavier when I roll it onto the substrate. Of course I won't know if this helps or not for about a year.

This has been a real blow to my confidence in using shop sawn veneer, with real concerns for the projects I've sold. I'm looking to see what others are doing, what your track record has been, what you think I might be doing wrong, etc.

Thanks in advance.

John