Darryl Keil Last Activity 2026-01-12 8:29 AM
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Anton Gerner

 
Subject : Glues for veneering
Posted : 2003-09-03 4:40 PM
Post #30962
We have been using Urea for our veneering with great results, but it just takes too long to dry! We are looking to use a PVA of some sort as we have to push the work through our 2 vacuum presses faster. We are only pressing flat panels. Has anyone tried Titebond II or Multibond EZ2 with good results. We are worried abour creep over the long term, so I need to find a single part glue that dried really hard, that dries in a up to 2 hours in the press.
Any coments most apreciated.


 
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Darryl Keil

Posts: 1456

Joined: 2003-05-22
Location: Maine

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Subject : RE: Glues for veneering
Posted : 2003-09-04 10:05 AM
Post #30963 - In reply to #30962
Anton,

I completely understand your dilemma, we all want the speed of a PVA with the rigidity of a urea. Unfortunately, the cross-linked PVA glues like Titebond II and Multibond do not really give you the kind of rigidity you are looking for. One thing you could try is to add heat when pressing with urea glues. These glues are very sensitive to temperature and set times will increase dramatically with the addition of heat. If you can develop around 100° you can bring your set times down into the range that you get with PVA glues. One other thing is to locate a faster setting urea. I don't know if you have tried our Unibond 800, but we have formulated it to be a faster setting urea, as far as urea's go.

There is another solution, you may want to try that I have been told about, but not tried personally. What you do is to mix a urea glue with a PVA glue about 50/50. Supposedly, the PVA glue gives you a bond in about an hour or two, and you still get a fair amount of rigidity because of the additional urea. Actually, I have sometime today to test this out personally. All post my results tomorrow.

Sincerely
Darryl Keil


 
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Anton Gerner

 
Subject : RE: Glues for veneering
Posted : 2003-09-04 4:34 PM
Post #30964 - In reply to #30963
Thanks Darryl, Your information was helpful.
I am looking forward to the results of your test.
The other problem we are having with Urea is staining of the veneer. We are in Australia and use a lot of darker timbers. The Urea seems to stain somme of these. It maybe the glue we are using. I would be interested to see what you could offer us, as I don't mind importing our glue from the USA if we can find the right product. Your faster one sounds good!
My email is anton@antongerner.com.au
Thanks, Anton Gerner


 
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Darryl Keil

Posts: 1456

Joined: 2003-05-22
Location: Maine

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Subject : RE: Glues for veneering
Posted : 2003-09-05 11:42 AM
Post #30965 - In reply to #30964
Anton,

OK, here are the results of my tests. I did three, mixing ratios, 50/50, 60/40, 75/25. The higher numbers are the urea glue. I found that you could remove them from the press within one to two hours at 75°. Of the three mixes, I like the 60/40 the best. The 50/50 was a little soft after the urea fully catalyzed and I think the 75/25 has too much urea in it to give you enough of a short-term bond. Mind you, these were quick preliminary tests on small samples. I would want to do more extensive testing for conclusive results. In general, I was pretty happy with the results. One additional thing to note is that I was using a liquid urea and measured the proportions by weight. I don't know exactly what the test results would yield using a powdered urea.

I'm not sure why you're getting staining, especially on a darker wood. Is the staining lightening the veneer or darkening it further? Is it possible that you are just getting bleed through and not removing it properly?

We would be happy to send you our urea glue, but I would think shipping would make it prohibitive, it's up to you.

Sincerely.
Darryl Keil


 
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Anton Gerner

Posts: 45

Joined: 2003-09-04
Location: Melbourne, Australia

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Subject : RE: Glues for veneering
Posted : 2003-09-05 4:01 PM
Post #30967 - In reply to #30965
Dear Daryl,

The test sounds interesting.
The staining we are getting is where the veneer turns a pinkish colour, it does it on Euro Beech also. Also the glue that does bleed through is impossible to get off. I reckon your Urea may be of higher quality to ours. Can you email me the pricing info? and tech info inc. drying times, etc.

Regards,

Anton


 
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Darryl Keil

Posts: 1456

Joined: 2003-05-22
Location: Maine

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Subject : RE: Glues for veneering
Posted : 2003-09-05 9:02 PM
Post #30969 - In reply to #30967
Anton,

I think you are getting a chemical staining on the beach. The catalyst in Urea can do that to some veneers as well as the crosslinkers in Titebond II and Multibond. See if you can back off the amount glue until you get very little or no bleed through. That should solve the problem, if I'm reading it right.

If you got to the top of the forum and click on "home" you will go to our web site and find veneer glue. Unibond 800 pricing will be there.

Sincerely
Darryl Keil


 
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mcnerney

 
Subject : RE: Glues for veneering
Posted : 2003-09-15 7:10 AM
Post #30985 - In reply to #30962
It seems to me I onced used an electric blanket to add heat. What do you think?
Also is creep really that much of a concern on flat panels? I thought it was mainly a concern onf curved parts?
mike


 
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Darryl Keil

Posts: 1456

Joined: 2003-05-22
Location: Maine

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Subject : RE: Glues for veneering
Posted : 2003-09-15 11:35 AM
Post #30987 - In reply to #30985
McNerney,

Electric blackets are a great way to add heat to a urea resin glue up.

Creep can definately be an issue with flat panels. Delicate veneers like mahogany crotch want to fissure up the center of the crotch. A urea resin glue can control this. Even the veneer joints can open up ever so slightly with the PVA glue and can be noticeable under the right light, especially with a high-gloss finish.

Sincerely
Darryl Keil


 
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Anton Gerner

Posts: 45

Joined: 2003-09-04
Location: Melbourne, Australia

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Subject : RE: Glues for veneering
Posted : 2003-09-15 4:49 PM
Post #30988 - In reply to #30987
Daryl,

I've been testing different Urea glues here and have managed to find one that works for us in 2-3 hours. I'll also try the electric blanket.
I was wondering if you have ever added wheat flour to Urea?
Our supplier suggested it to decrease bleed through, thus reducing staining on some timbers. I have tested it by adding up to 10% with good results.
Any other ideas to reduce bleed through?

Anton
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