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I've Had It With Uni-Bond!

2/4/14       
David R Sochar Member

I just looked at another veneer glue failure on another table top today, and this project was the last time we used Uni-Bond 800.

Since then we have been using Pro-Bond Urea plastic resin glue, but having a real hard time telling how much coverage to lay on. We are using a small diameter paint roller - 1-1/4" or so - and laying on pretty thick (to decrease paranoia). Put it in the vacuum bag and there is glue coming out everywhere.

Now I'm reading more and more about PVA with veneer(?!?). This is raw veneer we use, and often 1/16" or so in thickness. No paperbacks. Sometimes we cross band, sometimes not.

So the basics:

What glue should we be using?

How do we know we have the the proper amount? Do those dispensers work well? Or is it still just guesswork/experience?

2/5/14       #2: I've Had It With Uni-Bond! ...
Ed

Website: http:/qualityvak.com

You may want to consider a glue spreader with a smooth roller. Not only are they faster, however, they lay down a nice even layer of glue. Much more consistant than a paint roller. You can see some at http://www.qualityvak.com/access.html.


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Glue spreaders

2/6/14       #3: I've Had It With Uni-Bond! ...
Max Neu

David,
Have you tried or looked into any of the single component glues made just for cold pressing?I think titebond makes one,and another one called Better Bond.I know they have a shorter working time,but if you can deal with that,they might be worth trying.

2/6/14       #4: I've Had It With Uni-Bond! ...
Charles Member

David,

Do you mean "Pro-Glue" instead of "Pro-Bond"? I can't seem to find any urea glue call "Pro-Bond" while searching.

I did find Elmer's Pro-Bond, but I don't think it is a veneer glue. The description did not mention Urea Plastic Resin Glue.

Signed,
Confused

2/7/14       #5: I've Had It With Uni-Bond! ...
Ed

Website: http://www.qualityvak.com

If you are looking for a urea glue, go to http://www.qualityvak.com/glue.html. It's a powder urea with a 1 year shelf life.

QualityVak

2/7/14       #6: I've Had It With Uni-Bond! ...
John Van Brussel

Website: http://www.veneersystems.com

Hello David,

Unibond 800 or PPR (powdered plastic resin) are the best for veneering in my opinion. These glues are urea formaldehyde based, chemical reaction bonds with high water resistance and thermosetting. You will not have any springback or creep with these glues. As long as you mix properly, apply the correct amount and are above 70F in your shop during curing.

Powdered Resin

2/7/14       #7: I've Had It With Uni-Bond! ...
David R Sochar Member

Yes, I meant "Pro-Glue", but we are now using CP's cp-0503 pre-catalyzed powdered urea resin.

We quit the Uni-bond when the formulation changed to less formaldehyde. Not that I'm a fan of the stuff, but the glue starting giving us problems then - with adhesion.

My chief frustration comes from not knowing how to get the proper coverage. We use foam rollers - small o.d. type, but we are having to mix and roll out almost 3 times as much glue as they suggest.

Granted we are working with some really coarse 1/16" White Oak and cross bands, but we used almost a gallon of glue to do 4 door stiles - 90 s/f.

I am reluctant to use a PVA since it clashes with my old school "gluing must be hard" mindset. And the water base - even though the PPR we use mixes with water. Maybe I am just irrational about the whole subject.

John - We have the mixing down - lots of work and time to get rid of all those little lumps, and we have the temp easily at 70 or over (sweatbands in place), so it is coverage that I feel lost with.

Will those nifty looking rollers put out the correct amount of glue spread, or are they just like my paint roller but with a reservoir?

2/9/14       #8: I've Had It With Uni-Bond! ...
Bob

I stopped using Unibond years ago after one too many acid burn throughs ruined finished pieces (mostly occurred in light veneers). Not thorough enough mixing of the powder apparently. The info I got from them was to mix with a power mixer let it sit for 5-10 min. and then mix again with a power mixer. If any little clumps remained they needed to be broken up and mixed in again. Seemed like a lot of work to use a product when others like Pro-Glue don't require such hassles and work just as well with lower formaldehyde levels.

Also has a longer shelf life. Our last couple gallons of Unibond only lasts about 4 months in a cool shop.
Bob

2/10/14       #9: I've Had It With Uni-Bond! ...
John Van Brussel

Website: http://www.veneersystems.com

Hello David, The glue spreaders we sell are designed to put down the correct amount of glue. For the Urea Glue you need to use the grey rubber roller. My concern with using a foam roller would be absorption of the glue. We have been selling PPR (powdered plastic resin) glue for 20+ years and sell 1 gal., 5 gal, 100lb and 300lb drums.

Powdered plastic resin

2/10/14       #10: I've Had It With Uni-Bond! ...
Dave

What about using a wet film gage? IIRC 5-7 mils is recommended.

I use notched spreaders because it gives me a nice consistent spread. Even so, thickness can vary depending angle and pressure.

I test with samples I put in the press for a couple of minutes. Peeling off the veneer shows how well it gets covered.


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2/11/14       #11: I've Had It With Uni-Bond! ...
David R Sochar Member

It looks as if there are two solutions ready to use: The spreaders as suggested by John V B and the notched spreaders for smaller jobs. I'd like to have both at hand.

Any suggestions on where to find the notched spreaders and what are the dimensions of the spreaders?

2/11/14       #12: I've Had It With Uni-Bond! ...
Charles Member

Notched spreaders can be found at most hardware stores in the flooring department. They are used for spreading thinset for tile, adhesive for vinyl flooring, etc. There are many different sizes and shapes (V-notch, square-notch). I need someone else to suggest a size.

2/11/14       #13: I've Had It With Uni-Bond! ...
Dave

I haven't seen any notched spreaders small enough and haven't tried filling/machining down the smallest ones.

I make machined stainless steel ones ($20). The V notches are approximately 1mm (1+ edge, 1- legs) on 3mm centers. If the numbers I'm getting are right, and my scale is accurate (grams per square meter), the spread is only a hair over 4 mils. Whatever it is, they have worked well for me (even w/ unfilled PVA and porous quarter grain veneer).

2/11/14       #14: I've Had It With Uni-Bond! ...
Chris

1/16" notched trowel. I use a cheap plastic one from Local hardware store. Why all the hoopla about the rigid glues? If its a flat surface, in my experience, Tight bond 2 is just fine.

2/12/14       #15: I've Had It With Uni-Bond! ...
Dave

If I did the math right, the wet film thickness of a 1/16" V notch spreader is over 30 mils. My first spreader had 1/16" V notches almost 1/4" on center and that was too much for veneering w/ PVA. While, theoretically, it provided an almost acceptable 7.5 mill film, actual film thickness is usually (unless you really slant the spreader) higher than the square root of the calculated notch area.

2/15/14       #16: I've Had It With Uni-Bond! ...
David

I use a metal spreader from Ace hardware that has a 1/16" x 1/16" square notch pattern. I then file it down to a height of 1/32". I end up with a notch 1/16 wide and 1/32 tall. This puts on the perfect amount glue.

2/17/14       #17: I've Had It With Uni-Bond! ...
Dave

Correction to my earlier post: actual film thickness is less than calculations based on spreader notch area.
With my 1mm V notch on 3mm center spreader the calculated film thickness is 6.6 mils (.0394 x .0394 = .001552, / 4 = .000388, square root = .0197, / 3 = .0066). I did two tests to calculate film thickness using grams of glue used per square meter. Considering I used a 55 lb scale and relatively small test pieces (~.3 sq meters), the 4 and 5.6 mil results are surprisingly close. At least with unfilled PVA's, there is a fine line between 100% veneer coverage and porous quarter grain bleed through. Even with my relatively low notch area, I can get unacceptable bleed through if I'm not careful about cleaning up/removing excess glue - pressure and angle can make a big difference. While numbers are interesting, doing test samples is the only way to get a minimal glue line with 100% veneer coverage and no/minimal bleed.


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