WWA Info Exchange

OK, it's not really veneer in the truest sense of the word. I've resawn 8/4 stock into 1/10th" thick strips to achieve 1/4 sawn presentation. Strips are drum sanded to consistent thickness to 3/32". My vacuum press consists of a torsion box, 3/8" vinyl tubing 'gasket' cemented into a partial groove routed around the edges of the bottom portion of the press/frame. The cover is 40mil vinyl and the top of the frame also has a groove routed around the perimeter matching the tubing gasket. The vinyl cover is sandwiched between the frame cover and the tubing.

So far so good, it draws down pretty well.

But.

I finally found and rigged up a vacuum gauge to see just how much vacuum the pump was pulling. It shows only 20"Hg, something less than an ideal 28-29"Hg.

Completely shut off the intake port of the gauge and still only had 20". The pump is a salvaged unit with no documentation so I don't expect anyone to advise as to adjusting what I'm assuming is a relief valve somewhere. That said, given that my veneer strips are fairly flat by the time I get 'round to laying them up, does the collective opinion here believe the 20"Hg vacuum is sufficient to provide a good glue bond?

Second question -

I've been using Tite-Bond cold press veneer glue, the brown stuff that seems to have a high solids content. It's designed to prevent excessive bleed-through. I'm about to use up the last of this gallon and I'm wondering if, given that my veneer material isn't that thin if ordinary Tite-Bond wouldn't work as well. The cold press glue is more expensive and only available, to me, via mail order.

Oh - the substrate is 1/2" plywood, what's sold locally as 'Satin-Ply" meaning both sides are well sanded and smooth is all.

_________________
Nullum Gratuitum Prandium

Cheers - Dennis

I would think regular titebond would be o.k. A suggestion would be to look on www.Joewoodworker.com, there is a ton of informations on glues and veneers. You could also email them and ask your question, I have had pretty good response from them.

At 20" hg I think that is equivalent to 9.8 pounds per square inch.
I can't imagine why it would not be more then ample to do what you want.

What altitude are you? I know the pumps lose efficiency the higher you go.

Hope this is helpful!

Eric

I have a vac u clamp vacuum pump and it shuts of at 22 hg, so 20 should be o.k.

If you go to the vacupress.com website, Darryl has a forum, and an archive with every question ever asked about veneering.

I'm found that the best substrate is mdf. it does need to be veneered on both sides, but there are no movement issues and it will stay flat. I avoid useing regular tight bond, it is very pliable and subject to glue creep. Rigid glues and exoxy work best. Unibond 800 is great but spendy.We have had warping problems with plywood almost every time.

On handcut veneers I resaw 1/8th and sand to 1/10th. If you are doing any bookmatch, the 1/8th veneers can be jointed and glued together prior to pressing, I just use low stick tape and stretch it to glue the veneers together, and that works real well.

Len

Hey Dennis,

I agree with both Dennis and Len.

Given that you're up there in the hills above the Skagit, you might have some elevation effect, but you should have more than enough pressure to go the job.

I too would avoid regular TiteBond for veneering. You really want something that won't creep. I like Unibond too, but Weldwood plastic resin glue works well, but only if it's fresh.

Good luck,
Tom

_________________
"There is no path to peace, peace is the path."
Mohandas K. Ghandi

Wow! Speedy replies and stellar advice and guidance. Thanks to the bunch of yaz!

I'm curious as to why/how glue creep would be in issue in this application. I've always presumed that it was associated with structural stress along the glue line. Compared to the substrate, the veneer is negligible with respect to weight.

Tom and others: I'm at about 300' elevation. I suspect that every pound counts! (hehehe)

Popeye - I've used MDF for the lower cabinet doors with good results. I have none the less had problems with keeping it flat. The upper cabinet doors are wider and taller.

Truth be known, I was gluing up one side at a time which could have produced some moisture expansion problems. I'm working on my technique and orginization to get both sides laid up at the same time.

Glue wise, I'll wait for comments regarding the glue creep issue while welcoming any and all comment.

Thanks, folks....

_________________
Nullum Gratuitum Prandium

Cheers - Dennis

These guys use normal titebond for their veneer work... pretty heavy duty but it is subject to different stresses. I took advice from here to heart during my veneer project (used PVR glue) and didn't regret it.

http://www.roarockit.com/index.php

Lawrence

I would think that on the larger doors mdf would be an advantage, but both sides need to be done to balance the piece.

I hate to harp on the vacupress forum. but Darryl is the veneering guroo. There is a good tutoriol on page 2 of the forum about glue hardness, and lots of info about pva glue and why to avoid useing it. Although the cold press was the best choice of the pva group.

The problem with pva's are the moisture content of the glue which can cause the warpage. Resorsinol and other urea formaldahyde glues have no water base.

Best of luck with the project! Veneering is great!!!

Len

The thing I worry about most with respect to hanging things on the wall is weight, Len. That's why I opted for a plywood substrate rather than MDF. I freely admit to being paranoid.

I'd never heard of PVR glue before, Lawerence! Did a little on line reading and it looks like it would solve the problem of excess moisture in the glue. If I can find a source I'll give it a try.

_________________
Nullum Gratuitum Prandium

Cheers - Dennis

oops-- I meant PPR glue... my brain thinks of it as "plastic veneer resin" for some reason, it is "powdered plastic resin"

Sorry about that
Lawrence

Oddly enough, PVR glue does indeed exist:

http://www.timbecon.com.au/products/adh ... 371_0.aspx

It seems to only be available from this source, however.

_________________
Nullum Gratuitum Prandium

Cheers - Dennis

Kind of late but here is a web page on glues and it looks like the so-called Ultra-Cat is what they recommend for shop sawn veneers.

http://www.joewoodworker.com/veneering/glues.htm

Wow! Hebertoo. What a great source of info in that link!

Thanks.

_________________
Nullum Gratuitum Prandium

Cheers - Dennis

well I never....

Of course I made that faux-pas on purpose as my research obviously uncovered this in a previous...

oh what the heck... awesome link, I'd never heard of that before. Thanks for sharing.
Lawrence