Checking my veneer thought process

[sean meltvedt]

First time veneering. I’m planning on gluing shop made 3/32 veneer onto the hood below. I put a face board on the bottom vertical area to create a ledge, and dry fit the veneer by pressing it down from the top. It fit to the curve well. So the plan is to use epoxy rolled out on the hood. Put the veneer on by pushing it down from the top against the face board using a few staples at the top to hold it. Finish with a j roller to eliminate the air bubbles. (The staples at the top will be covered with trim during the install.) the sides will be done first. Then the face last. I don’t have a vacuum setup so that is not an option, and the convex curve doesn’t lend itself to the iron methods I’ve been reading about.
So do you folks think my plan will work?
any thoughts, suggestions, or comments?

Thanks
Sean
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[Max Neu]

You could use some thin plastic laminate (vertical grade) and some sand bags to hold it down while the glue sets.

[Philipp Jaindl]

It should work provided you veneer both sides and the staples are strong enough, only veneering the outside has a very high Chance to warp it since theres no force to counteract the pull of the veneer.

Though im unsure how good of a glue bond you're gonna get without applying pressure on the entire surface, you could make a "negative mold" out of 2x4s and some plywood to get straight edges for clamping, provided you have clamps large enough or a veneer press, this is the way its usually done, afterwards you Assemble the pieces.

Cant think on anything else right now.

[Robert Engel]

I am by far no expert but the big problem I see is trying to veneer this after assembly.

Any type of curved surfaces are best done in a vaccuum press. I suppose you could hammer veneer but you'll probably have an issue using hide glue if this is a range hood.

Definitely veneer the other side.

If the grain is vertical I think I would moisten the veneer and lay it on with sand bags to train it to curves before gluing.

The Shipwright over on Lumberjocks is extremely knowledgeable. You might want to post over there, too.

[Jim Becker]

I agree with Robert...veneering this piece after assembly is a lot more difficult. Max's idea of doing one surface at a time and using something thin and very flexible combined with weight (sand bags, et al) to hold things in place while the glue cures is a good idea. You'll need to be very careful about squeeze out at the corners with adjacent surfaces...tape should be your friend there.

[Tony Leonard]

Hmmm, interesting challenge there! I would definitely try to make some sort of clamping arrangement -several good suggestions already. I would be a little concerned about the screw holes too. 3/32 is pretty thick, but there is a chance they could telegraph through. So, how are you going to make a piece of veneer big enough to cover that? Whew, the more I think about this, the harder it looks! I rarely cover both sides with veneer, so I wouldn't be too concerned there. Do you know anybody that could loan you a vac bag? Even with cauls, you won't get a good even spread of force and the veneer might end up wavy. I have never used contact cement, but that would be a thought here. I hesitate to mention it because I don't trust it. I'm stumped. Please let us know what you come up with and how it turns out. Nice curves on the hood though - very graceful.

Wonder if you could glue in sections. Hmmm, just thinking out loud here.

[Jim Becker]

Good point about the screws, Tony. The screws likely should be sunk just below the surface and then the depressions and screw heads get filled with something hard like epoxy or bondo and sanded flush before moving on to the veneer work.

[larry senen]

i used to make my own double ply with aircraft 3 ply,but i laid it up in a vacuum press.then a contact cement to the piece . i would mask off the edges and use yellow glue on them. tape is enough to hold the edges while the glue dries .anderson is where i got the 3 ply.

[John C Cox]

Ok.. So I re-read your OP and your veneer will conform nicely to the surface cold.. Without any hot bending..... That's great!!! It will save you a ton of work hot bending all the parts and making a hot box and forms.....

I would make up a set of long cauls that match the surface and glue them up that way... Unfortunately - it's a huge gluing surface.... Perhaps make the cauls with a convex bow longwise so they will clamp pressure into the center as you tighten the clamps on the ends.... 2x4's would probably work well for these long cauls.... And a million long clamps. Fit each one to the work - and number them all so you have them in the right order...

I would not use screws or staples... They are more likely to blow through....

Glue wise - I think slow cure epoxy would be a good choice here... As you will need a LOT of open time to get all your cauls and clamps into place.

[andy bessette]

...the depressions and screw heads get filled with something hard like epoxy or bondo and sanded flush before moving on to the veneer work.

I would avoid Bondo type fillers as they continue to shrink, over time. No such problem with epoxy.

[Philipp Jaindl]

Agreed with the others you'll need to fill up sand the screw holes and heads flush.

Another Problem that i see is how do you trim the Veneer flush? I'm not to sure a router is gonna work well on a curved surface, especially assembled. If at all possible id say Veneer all pieces seperately and assemble them later, thats gonna make things easier.

[Jim Becker]

I would avoid Bondo type fillers as they continue to shrink, over time. No such problem with epoxy.
Thanks for the clarification, Andy. I didn't know that about "bondo"...'never used the stuff, but I know some folks do. Epoxy is easy, too.

[Peter Christensen]

I would have made a MDF egg crate form and put it on that CNC router in the background and cut the curve. Then applied some plywood or hardboard to the curve. Laid a sheet of plastic and then the backing veneer, couple layers of thin plywood, the face veneer, a sheet of plastic and another thin sheet of plywood or hardboard over it, clamps and cauls and maybe a bunch of sandbags. Once everything was cured I would have cut the 3 parts out and attached them to the hood frame from the inside. All the veneered pieces would have the same curve so you get nicely matched corners. The form could be used for other projects like a headboard for a sleigh bed or a curved table pedestal, glass topped coffee tables or curved islands etc. You could have made the form as convex and veneered that way if you preferred.

Where you are now lay it on the side propped up so it is comfortable to work on and use sandbags to hold the veneer. Repeat with the other side and finish with the front. Put in a few temporary braces in the hood before you start.

[Jamie Buxton]

If you hold the veneer on with mechanical clamps while the epoxy cures, examine the resulting panel carefully. Tap and rub around on the veneered surface, listening for voids. If you find any, drill through the substrate from the inside, and flow more epoxy into the void. With thick veneer on the outside, you can drill -- carefully -- without going through the veneer. If you can, add clamping to the outside to reduce the void thickness.

[Jamie Buxton]

Good point about the screws, Tony. The screws likely should be sunk just below the surface and then the depressions and screw heads get filled with something hard like epoxy or bondo and sanded flush before moving on to the veneer work.

The veneer is 3/32" thick. It will easily bridge over the holes for the screw heads.

[sean meltvedt]

Hey guys, thanks for all the ideas and advice. Veneering prior to assembly is not within my current capabilities. The edges of the hood have to be shaped by sanding in the same horizontal plane with the face installed in the curved position(the curves cause the mating angles to vary along the edge.)
Peter, unfortunately the CNC is constrained by the skill of this operator. :-) I did use it to create the inner frame structure so the front and side curves are identical. It is also too late to avoid bondo. As a previous hobby experience included car restorations - I have a lot of experience with it. The corners are floating, but have been epoxied and have a rear fillet with fiberglass in the epoxy resin. I thought about trying titebond after the sticker shock I got with pricing on the epoxy for the veneer glue, but I'm sure that probably wont adhere to e polyester filler (bondo). What's the consensus about using a polyester resin (fiberglass resin) as the veneer glue?

[John C Cox]

Laminating resin works well enough on wood... It just has a fairly short pot time.. And a LOT of resin can soak into the wood... It can also soak into and through wood ESPECIALLY into endgrain - making the wood VERY blotchy (test on scrap ahead of time)... Clear is bad enough - quite a few laminating resins are blue, green, or brown - which look horrible when they soak into the wood.... Most resin also darkens wood kinda like a wood finish... I had some laminating resin soak about 1 foot up into endgrain.. Left a horrible blotchy mess. Ruined the whole piece.

That's actually one of the beautiful things about proper wood glue - they already worked out these problems.... It is designed to size the wood - so it doesn't soak in and leave a blotchy mess or darken glue joints..

As per usual - test on scrap....

[andy bessette]

...What's the consensus about using a polyester resin (fiberglass resin) as the veneer glue?

IMHO polyester is an inferior wood glue. I use WEST epoxy.

[Dave Gagnon]

I think contact cement would work really well. I have veneered many things, some with curves and have always used contact cement without issue. I have never had any of the veneers lift and the bond is instant and permanent so no need to worry about how to clamp it down. Since your veneer is 3/32nd thick, I don't think the contact cement would soak through either..

[Mike Wilkins]

How about contact adhesive? With a thicker veneer there should not be any concerns with bleed-through. But if you do use contact adhesive, it would be a good idea to solicit some additional hands to place it in place on that curved surface.

[Robert Engel]

Sean after seeing the hood, have you considered painting it?

[sean meltvedt]

Robert-that is really not an option. My wife would be out to kill me if I did :-) I would attempt to source some PSA backed Makore as a last resort.
Anyway I appreciate all the thought's and ideas that folks have posted.
Thanks
Sean

[sean meltvedt]

Hey guys-just a progress update. I used Max’s suggestion of sandbags in addition to clamps using West systems epoxy. This is the workable result:
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[Tom Giacomo]

Looks very good.

[johnny means]

Contact cement is standard practice in commercial shops when bending things like this. No, it's not going to last 100 years. Yes, you will get good adhesion and a predictable, manageable lay-up.

[Mel Fulks]

I agree the contact cement is often used. Don't agree it's a good idea on a material with a lot of spring-back. Call the help line for contact cement mfg ,they will tell you the FLAT surface bonds will last about 10 years on average.

[andy bessette]

MF--good post.

[John Blazy]

35 years of experience in weird laminating, veneering and exotic adhesive use tells me that most advise here is good, but will add a few points: Contact cement is great on thick veneers like this, as long as its layed on thick and pressed thoroughly, but long grain spring back like Sean did is a little questionable, so glad he epoxied (I pictured the grain going opposite direction). Epoxy only needs veneering on one side. The old law of veneering both sides only applies to glues that shrink, or glueing to solid wood. Veneeriing one side of ply with epoxy is fine.
The nice thing with epoxy, is that if Sean got voids from uneven pressure, he can syringe epoxy into the voids later.

If you ever do this again, its much easier to veneer your curved parts ahead of time, while bending at same time. It doesn't take long at all to make a bending form, then glue up the bending plywood (3/8" bending luaun or multi layers of 1/8" BB plywood) and the veneer all in one glue up. Use a stiff caul over top made from 3/8" plywood faced in 1/2" styrofoam for even pressure, with 2 x 2 cleats on long edges to clamp at edges, no need to clamp middle as the stiff caul will be adequate pressure with epoxy.

You can see the similar shape in the pcs below, and I used a 2" long flush trimmer to clean the edges prior to sanding, and made a custom hand held 6" DIA drum sander for sanding the concave surface (Upper central part of last pic).
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