Veneer gluing failure.

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sihollies

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Hi
I have just glued a marquetry image to a box lid, which I have done dozens of time previously with no problems, but this time I have failed for some reason :( .( Maybe too much adhesive??)
I am using PVA, as usual, but on this attempt the veneer hasn't adhered to the substrate and has left a rippled effect on about a 2 square inch area.
I am pretty sure that I have read somewhere, that one can 'iron out' this defect?
Any advice will be appreciated, as I really don't want to re cut the marquetry image

Thanks in advance
Simon
 
PVA is not a thermal adhesive so I wouldn't expect heating it to make it go soft and allow the marquetry to move.
Veneering is not something i've done yet but at the W18 show, Tensorgrip were running demos of their range of professional adhesives and they were using spray contact adhesive for veneering. Just a thought. You can buy it in spray cans.
 
It looks like heat softens PVA - see:

https://www.oakwoodveneer.com/ironon.html

I suspect it weakens the glue joint, as heat does with Titebond Original, but is should still be strong enough for a non-structural application like veneering.

If it fails, I can't see that you've lost anything, so long as you don't use too high a heat and scorch the wood.
 
sihollies":rzkfsfyp said:
Hi I am using PVA, as usual, but on this attempt the veneer hasn't adhered to the substrate and has left a rippled effect on about a 2 square inch area.
Simon
You can use an iron to stick veneer to a ground. I've used the technique many times over the years, primarily to attach veneer edging to various panels. In those cases, I usually cut strips of veneer, ~25 mm wide to attach to an 18 mm thick panel veneered in the same material. I apply the PVA or aliphatic resin to the panel edge, position the veneer edging, and run over this with a warm iron.

There's another related technique some people use for laying veneer on the wide ground where they apply PVA/ aliphatic resin to the ground, let it dry, position the veneer on top of the dried adhesive and apply heat using an iron to stick the veneer in place. I've only ever experimented using this methodology with odds and ends of veneer offcuts just to see how well it works. To be honest, it's not a technique for which I've developed much confidence, and I've always had other methods available that I do trust, e.g., hammer veneering, bag press, vacuum bag veneering, mechanical presses, and so on. However, I'm aware that quite a few people report good success using the heated iron technique on dried glue method so I won't and can't say it's a poor method, primarily because I haven't experimented enough with it to form a good opinion.

So, as profchris has said, you have nothing to lose by trying, and I can report I've successfully rescued veneering jobs with similar problems using the warm/hot iron technique. But it might be worthwhile adding a wrinkle and try to find out the cause of the bubbling veneer. It could, for example:
*1. too little glue
*2. a contaminant, e.g., oil or wax for example on either the ground or the veneer, or both
*3. lack or no pressure on that spot
*4. particularly strongly wrinkled veneer that perhaps ought to have been softened and flattened before attaching it to the ground

If it's 1 or 3 above, you might even be better to make a slit with the grain, or lift up edges of your marquetry and feed some extra glue in before you apply heat in an attempt to fix the problem. If it's 2 or 4 you're much less likely to have success, and you'd need to address those problems, which would probably be fairly difficult in an already glued down pattern, meaning you might have to take more drastic repair measures. Slainte.
 
Many thanks for your replies and suggestions.
I decided to give the heat/iron method a go, as like you stated, there was nothing to lose.
For info: I sprayed the veneer slightly with water and protected the veneer with brown paper and set the iron to a medium heat, and after a few attempts, I am pleased to say it was a success. seam (with the help of a veneer roller)
So furthemore, thanks again for your help.

Simon
 
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