Polyurethane / Urea Formaldehyde Glue Question

[James Jayko]

Hey all...

I made a mistake in a project and need to plug a hole. The final project is going to be painted, but I don't want the repair to telegraph through the finish. I know Unibond 800 dries with a very hard glue line (IE the wood is far less likely to protrude or indent due to wood movement). I have some Unibond, but its a PITA to use and I'm curious is Gorilla Glue dries in a similar fashion? IE would Gorilla Glue be the better choice over Titebond to ensure that the final product looks as good as possible? Any advice would be very helpful.

[Jim Becker]

The issue with polyurethane glues ("Gorilla", etc) is that they really are not gap filling and tend to foam up in such situations. How about bondo?

[Frank Pratt]

Gorilla polyurethane doesn't cure all that hard, so I doubt it would be any better than PVA in that regard. Where I'm concerned about telegraphing through paint, I've had good results from cutting a very shallow (1mm) depression along the glue line & then using Bondo to fill it. Without that depression, the line still tends to telegraph.

[Rich Engelhardt]

There are now non-foaming polyurethane glues that are clear.

I bought some to try out on a hard rubber with a metal insert foot that broke off my shop stool. It says it's good on al sorts of things - wood, metal, glass, ceramic and some types of plastic.

Gorilla makes one also.

FWIW - it seems to (so far after a couple weeks) have worked on my shop stool.

I have some jigs and fixtures to make & I plan to use it on those.

Tom Silva was using it on Ask This Old House about a month ago. He's usually pretty good about stuff.

[Jamie Buxton]

There are now non-foaming polyurethane glues that are clear.



Brand name?

[Rich Engelhardt]

I used the Gorilla brand one.
This one:
https://www.amazon.com/dp/B06WD6R96X/ref=emc_b_5_t

[James Jayko]

Wasn't planning to fill it with glue, rather, to use the glue with an appropriate dowel. Just want to minimize the chance that the plug shrinks and telegraphs.

[John TenEyck]

Standard Gorilla Glue does give a hard cure, just like Plastic Resin Glue and Unibond 800. It would be a good choice for your application with a snug fitting dowel or other patch. Epoxy would work well, too.

[Joe Jensen]

How large, if under 3/4" Dia I'd use bondo

[Jim Becker]

Wasn't planning to fill it with glue, rather, to use the glue with an appropriate dowel. Just want to minimize the chance that the plug shrinks and telegraphs.

Most dowels are end grain and are generally going to telegraph their presence regardless of the glue you choose to fasten them in with. You may have better results with a plug thats the same species and grain orientation/pattern of whatever you are, um...plugging.

[James Jayko]

Most dowels are end grain and are generally going to telegraph their presence regardless of the glue you choose to fasten them in with. You may have better results with a plug thats the same species and grain orientation/pattern of whatever you are, um...plugging.

That's a great point; I wasn't thinking about the grain direction. I think I'll try one of those epoxy putty sticks. Thanks!

[Frank Pratt]

That's a great point; I wasn't thinking about the grain direction. I think I'll try one of those epoxy putty sticks. Thanks!

Cut a plug to fit & orient it so the grain runs in the same direction. A plug will be more likely to not telegraph than epoxy putty. The wood plug will move the same as the surrounding wood. Most plug cutters put a slight taper on the side, so you can be guaranteed of a tight fit.

[Jamie Buxton]

I do see the claim that Gorllia Clear is non-foaming, but I can’t see any claim that it is polyurethane. In fact, I can’t find any indication of what kind of glue it is.

[Richard Coers]

That's a great point; I wasn't thinking about the grain direction. I think I'll try one of those epoxy putty sticks. Thanks!
Plugging with a dissimilar material would be a mistake in my opinion. Not many manmade products have the physical properties of wood. That means you are looking at an easier telegraphing problem. Follow Jim's advice. I'd also suggest that if you plug it with the same face grain wood made with a taper, the glue line will be basically zero.

[Rich Engelhardt]

I do see the claim that Gorllia Clear is non-foaming, but I can’t see any claim that it is polyurethane. In fact, I can’t find any indication of what kind of glue it is.It is a moisture cured material - the directions on the back tell you to dampen one of the surfaces & apply the adhesive to the other.
It is paintable - which would pretty much exclude the moisture cured silicones.

This leaves the moisture cured urethanes.

[Tom Bender]

Drywall plaster may work well. Depends on the paint. Test it.