PUR Glue for Cabinet Assembly

Thoughts about the characteristics of hot-melt PUR glue, gluing equipment, and the requirements of cabinet construction. May 23, 2007

I'm curious about hand held PUR glue systems for assembling furniture. We have been using Wilsonart 20 PVA for the last 286 years and clamping. I'd like to know if these systems can be used successfully in bonding face frames, building cabinet boxes, and building drawer boxes without the need for clamping. I have read that some PUR glues can set up in 30 seconds - 15 seconds to apply and 15 seconds holding the part in position and it's completed. Have any shops switched to PUR? How well does the glue work/bond? What system do you recommend? Cost?

Forum Responses
(Furniture Making Forum)
From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
PUR can be cold setting or can be a hot melt. There are many varieties. Incidentally, PVA was invented in 1948, I believe.

From the original questioner:
I was only aware of the hot melt systems. I'm just basically trying to find out if this gluing system is worth the time to take a serious look at; is it practical, and how well does it work? Cost?

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
I have several clients that use hot melt PUR and are delighted. It takes a little skill and effort and quick handling. It is so easy to clean squeeze out, that they really like it.

From contributor V:
Doc, how would the squeeze out be easy to clean, as it would be dry and/or hard by the time you finish assembly?

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
It is apparently too cool to soak into the wood.

From the original questioner:
The systems I have seen resemble giant turbo charged hot glue guns. I have a feeling that Nike uses the same systems to assemble shoes. If 12 year old kids can do it, our assemblers can too. Don't stop there, tell me more about these systems.

From contributor V:
Doc, in all honesty, charts aside, will the pur glues give a strong enough bond to build 800 lb tables and other items that are well used?

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
I worked with a company that made miter joints for cabinet doors and the breaking strength of the pur hot-melt door joints was 95% of the strength of their old joints. The adhesive is close to the strength of wood in the literature I have from 3-M. The hot glue guns were roughly the same size as any hot glue gun I have seen (except for the hobby ones).

From contributor W:
I have heard elsewhere that the glue line is thick and highly visible. This may depend on factors such as open time, but it would seem that a thick glue line is likely with this system. Might this result in erratic bond strength depending on speed of assembly?

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
The glue line can be thick, but it does not have to be... that is my understanding and what I observed in production. I do not recall that 3-M (in the case I worked with) had a thickness specification that required thickness, but I will see if I can check that. A good feature is that it does not crack open if parts move slightly.

From contributor C:
I've tested the Jet Weld from 3M and found it to be the only thing that would reliably glue melamine to pine in 20 seconds without clamping or clean up (squeeze out = too much). Tensile testing consistently showed substrate failure before glue line. It can be a pain with the preheat oven to remember, but it's a short learning curve. The local 3M rep was happy to leave us a gun, oven, and a choice of cartridges with different open times. It don't cost nuttin to try.

From contributor H:
We bought a 3M gun for applied mouldings and to join crown before staining. Call 3M and have them do a demo and leave you the gun to try. Pay for a few cartridges and try it out. You have to work fast and be on top of the heat time, alignment, using all the cartridge or sealing it well. It is far from idiot proof and not cheap. Mine is sitting collecting dust and I am sorry I bought it, but I have to admit that I have not had the patience for it. Thought it would be a miracle answer.