Yellow glue vs. polyurethane?

[lkesteloot]

I set up my saw a few weeks ago. I love it! I've been having a great time.

I'm currently building a prototype of a shelf that will require great glue strength. I asked at Home Depot and they recommended polyurethane glue. I've always used yellow glue before, but I tried both on this project. I understand that polyurethane is stronger and waterproof, but seems to be more toxic and more difficult to work with (if it touches your skin you have to wash in warm soapy water for 5 minutes, etc.).

But I've also heard that both of these glues are "stronger than the wood." If that's true, then should I bother with the polyurethane glue? What's the advantage? Is it nicer to stain?

Also, what do they mean by waterproof? With yellow glue, if water gets on the glued pieces, the glue will soften and the pieces may come apart?

Thanks,

Lawrence

[Michael McBroom]

Yellow glue is "friendlier"

Lawrence,

If a glue joint is properly prepared, yellow aliphatic resin glue is indeed stronger than the wood it binds together. Still, though, if the project will be subjected to high stresses, it might not be a bad idea to supplement the glue with doweling, dovetails, etc.

I use the regular Titebond stuff for most of my gluing applications. I prefer it not just because of its more-than-adequate strength for the stuff I do, but also because clean up is easy. Plus I've even found that the yellow color of Titebond tends to hide glue seams in most woods better than the white aliphatic resin glues (the white glues tend to show the seam as a gray line). However, if I know that the project may be exposed to moisture, I prefer using Titebond II, which is water resistant. There's also Titebond III, which from what I understand is even more resistant to moisture, but I've never used it so I cannot comment on it first hand.

Best,

Michael

[LCHIEN]

i agree that yellow glue is friendlier.
You can use the waterproof stuff if you think it will be exposed to water.
Application is important, make sure both sides are well wet with glue.

The polurethane expands and foams so clean up can be a real problem.

[cwsmith]

You didn't mention the type of joint that you intend to use and I would echo the previous suggestion for using dowels or whatever structural joint you joint you are most experienced and comfortable with. I prefer the Titebond glues, especially Titebond II, which has some water resistance. I haven't tried the "III" yet. The "white" glues and "Hide" glue don't seem to hold up over time, especially if the project is going to subjected to any moisture or humidity. (At least that's my limited experience.)

I haven't tried any of the poly glues on wood projects as I am of the opinion that clean-up would be a challenge. I did recently use some "Gorilla" glue on a metal fan that came off my little "Stinger" shop vac when it fell off the table. When the fan blade fell off, I was at a disadvantage as to how I was going to fix it, when I remembered I had a free sample of the Gorilla Glue. First time I had ever tried it and for a metal to metal contact, I was quite impressed. I imagine it would work well on wood, but it foams and expands which would make it very sloppy I think for any woodwork. I have no other experience with "poly" type glues.

CWS

[Jeffrey Schronce]

But I've also heard that both of these glues are "stronger than the wood." If that's true, then should I bother with the polyurethane glue? What's the advantage? Is it nicer to stain?

Also, what do they mean by waterproof? With yellow glue, if water gets on the glued pieces, the glue will soften and the pieces may come apart?

IMHO Titebond II is the way to go if it is an all wood project. Polyurethane glue is not nicer to stain, infact it does not stain at all. I read Gorilla Glue website and it states it is stainable and paintable. I could not disagree with this more. The website states that it leaves an invisible glue line. Huh? That only occurs if there is no seepage out of the joint, otherwise it is quite visible, in fact is says that it dries to a light tan color right under where it says it is not visible. Polyurethane glue requires that the joints be wet with water prior to application. The glue then foams as it cures. The glue is tough as nails when it dries. It is great for joining different materials, such as ceramic to wood. If you are a new woodworker, Titebond II is going to be more forgiving. Your question of water proofing, no Titebond II will not become solvent if exposed to water for short periods of time. This is more relevant to outdoor projects or those that are in very high humidity areas. I would then go to Titebond III for a all wood project.

BTW, you will find a few knowledgable people in HD, but for the most part they know what the vendors sales reps tell them.

[drumpriest]

If the joint is a long grain to long grain joint, then yellow glue is ample, the wood would probably fail before the glue joint. If the joint is end grain to long grain or end grain to end grain, then neither will make a greatly strong joint. You should look into some form of joinery if this is the case. So it depends upon what you are doing, are you trying to make a shelf wider or longer??

Wider, yellow glue, titebond III for a good waterproof as stated above.

[JimD]

I have used both but I only bother with polyurethane glue for outdoor projects. Titebond III may eliminate the need for it even for that application. I have used Titebond I, II, and III. The main advantage of III is the longer set-up time IMHO. If you have to assemble a bunch of joints at the same time, it can help. Titebond I is water proof enough for indoor furniture projects. With a finish, there should be no water that gets to the joint. If you are worried, you could always go with Titebond II (or III). I do not see where strength is a basis for the choice. They are all strong enough if the joint fits correctly. If it doesn't, go with epoxy. It is the only glue I can think of with decent strength if there are gaps.

Jim

[jarhead]

I think I read somewhere that if you're going to glue lumber with high moisture content (i.e. 2x4's), polyurethane glue is the way to go. In fact, I want to build another workbench using 2x4's and wonder how much truth there is to it.

[lkesteloot]

Thanks guys! I'll look for the Titebond II glue.

Lawrence

[Imadunatic]

i use titebond III exclusively, now

it did take a little while to get used to the lack of initial tack and the fact that you want to let a glue up cook in the clamps longer. (no less than an hour, and thats not etched in stone)
another reason i love it is the fact that the application temp is as low as 47 deg.
not that i do hardly any glue ups when its that cold (or much of anything else for that matter, thats what we have heaters for, lol)

i dont think you're going to go wrong no matter what you choose. (i wouldn't recommend elmers school glue though, lol)


good luck on your project and have fun.

Kevin

[Jeffrey Schronce]

I saw an ad in FWW for Titebond III and in the text it said "Plus it's vastly stronger, safer, easier to clean up and less expensive than poly glues".
I wanted to get a little more info, so I checked Titebond.com and compared their TB III v. TB Poly.
TB III - Bond Strength on Hard Maple is 4000 PSI
TB Poly - Bond Strength on Hard Maple is at 3500 PSI+ at room temp
3000+ 150 degree overnight

TB III Product Features :
Passes ANSI/HPVA Type I water-resistance
Waterproof formula that cleans up with water
Superior strength - strong initial tack
Designed for interior and exterior applications
Longer open assembly time
Lower application temperature
Unaffected by finishes
FDA approved for indirect food contact
Conforms to ASTM D-4236

TB Poly :
100% waterproof (Passes ANSI Type I & II water-resistance testing)
Bonds virtually everything
Epoxy-like strength - no mixing
Short clamp & fast cure
Excellent sandability
100% solids
Solvent free
Conforms to ASTM D-4236

For woodworking it seems TB III has everything one would need. Poly may have an advantage outdoors.