The Bull vs The Gorilla

[Ed_McDonnell]

OK, now that I've got you in here you might be disappointed to learn that I just want to talk about boring polyurethane glues. I hope not!

I've been using elmers Ulitmate Glue (with the blue bull on the label) for pens and segmented turnings. No problems to report. I was just in the store to buy more and I thought I might give Gorilla Glue a try. I was shocked to find 8oz of Ultimate for $7 and 8oz of Gorilla for $13.

Could Gorilla Glue possibly be twice as good as Ultimate Glue. Is it any better at all. I'm tempted to say "polyurethane glue is polyurethane glue, No difference", but I've learned that not all CA glues are the same.

Does anybody know or have opinions. All facts and even wild speculation are welcome.

Ed

 

[Ron Sardo]

Price not being a factor, I like Elmer's better.

 

[Malcolm Tibbetts]

Ed, I've used gallons of Titebond Original for my segmented work with no problems. I've also used a few gallons of Gorilla glue over the years. I usually limit my use of polyurethane glues to those situations where I simply need more assembly time. The stuff is so messy, I avoid it whenever I can, but it is good glue.

 

[john lucas]

I don't like Polyeurethane glues. I like Titebond for most applications. Anything that I think would need something like Poly, I just use epoxy. It fills gaps where poly won't. It's easier to clean up. I can make it slow or fast setting depending on what I use. In quantity it's about the same price or better than Poly.

 

[tdrice]

I just lost a piece of a platter I was turning.-Buzzed past my ear and hit the wall -Ist zerbrochen ( that's fractured german for busted all to h--l). The gorilla glue that I used to stabilized a partial break until I could get it turned far enough to use a decorative fill did not fill the gap like I thought it would. I have not had good luck with gorilla glue. I may try the bull but mostly I will go back to titebond and CA as much as possible.

 

[Ed_McDonnell]

Thanks for all the replies. I searched around on the web some more after posting my question here. I came across a research study from Forest Labs that compared 4 different polyurethane glues available to consumers. They didn't identify what the specific brands were, but the test results were similar enough to make me feel comfortable with using lowest price as a criteria in selecting which brand of polyurethane glue to purchase.

I really like polyurethane for pens and I've learned how to glue the tubes into the blanks without making a mess.

I started using polyurethane for my segmented turnings because I thought it would be a lot stronger. After reading Malcolm's reply I figured that if Titebond can hold his complicated creations together, it will certainly hold my stuff. Then I came across a test of wood glues done by Wood Magazine. Their results were interesting:

For edge-grain joints, PVAs (titebond) and polyurethanes all produced joints stronger than the wood (wood broke before joint in test).

For edge-grain to end-grain joints most of the test joints broke, but PVA joints were 2 to 3 times as strong as polyurethane. A few of the PVAs were even able to produce joints in this instance that were stronger than the wood. (Elmer's probond interior, Titebond Molding & Trim, Loctite Professional Wood Worx).

So it would appear that polyurethane isn't worth the extra expense and mess for edge-grain joints and it is a vastly inferior choice for end-grain joints.

Learn something new everyday.

Once again, thanks for all the replies.

Ed

 

[john lucas]

Are you trying to glue the brass inserts in the pens. PVA isn't the best glue for that. It doesn't bond to metal all that well. That's why I use epoxy.
I tried a test on PVA, Gorilla glue and epoxy. My test was pretty unscientific. I was testing end grain to endgrain because I had a project that required that. I cut 6" long by 3/4" square pieces of 3 different woods. I glued them all together end grain to endgrain with the 3 different glues I mentioned. I tried to use the same pressure so the joints weren't starved of glue.
I let them dry for 2 days. Then I clamped one end in a vice . I clamped a 2 foot long board onto the other half. Then I put a 10lb weight on the extended board close to the clamp and glue joint. I slid the weight out until the joint broke and measured the distance. The PVA and Gorilla glue joints were extremely weak in this instance. Both were about the same. The epoxy joint was noticeably stronger although it broke much sooner than I would have thought.

 

[Ed_McDonnell]

John - I rambled on about a lot of different things in my last post. Sorry for the confusion.

I was talking about both brass tubes for pens and segmented turnings (bowls, hollow forms,...).

WITH REPSECT TO BRASS TUBES IN PEN BLANKS:
I use polyurethane to glue the brass tubes into the pen blanks. I agree that PVA (Titebond) is not a really good choice for this because it doesn't do well where gaps may be present. While epoxy would work well, when I'm gluing up 50 pen blanks at a shot the polyurethane is a lot less hassle and sufficiently strong.

WITH RESPECT TO SEGMENTED TURNINGS:
PVA is a good choice for segmented turnings. If end-grain glue joints are involved PVA may actually be a better choice than polyurethane.

WITH RESPECT TO END-GRAIN GLUE JOINTS:
Prior to getting involved with woodturning I did a lot of "traditional" woodworking. This of course involved end-grain joints from time to time. When making furniture or cabinets, I would never use an end-grain joint that wasn't supported mechanically somehow (biscuit, dowel, tenon, dovetail, pocket screw, whatever). I appreciate that in segmented turning or when laminating turning stock (like for multi wood pens) you sometimes end up with end-grain glue joints where it just isn't possible to mechanically reinforce the joint.

The Wood magazine test that I cited in my previous post had two noteworthy conclusions (it's the September 2004 issue if you want to check methodology and all the details):

PVA glue was 2 to 3 times as strong as polyurethane in end-grain joints.
Three PVA glues were somehow formulated so that they actually created end-grain joints that were stronger than the wood.

After rereading the above, it appears that my attempt to clarify is just as wordy as the original post. Oh well.

Ed

 

[Malcolm Tibbetts]

Ed, I agree with the unacceptability of end-grain to end-grain joints in most woodworking, but if you think about it, almost all of those types of joints in segmented turnings are reinforced by the brick-laid effect of off-set vertical seams. The result is really just a series of continuous mortise and tenon type joints which are very strong. Just to repeat from my previous posting, PVA or Titebond Original, to be specific, is my recommendation for this type of work.

 

[AtSam]

PVA glue was 2 to 3 times as strong as polyurethane in end-grain joints.
Three PVA glues were somehow formulated so that they actually created end-grain joints that were stronger than the wood.
Ed

I have used end grain to end grain joints without a problem in decorative turning. Meaning stuff that wasn't handling a load of any kind.

There is a method of sizing the joint with a 50/50 mix of water and PVA glue wiped on to seal the pores. Note, this is very thin coat. Let dry, then glue the end grain to end grain joint as you would any joint. I was shown this method by Michael Hosaluk while making his well known containers.

Container Reference- http://www.turnwood.net/michaelhosaluk_1003.html

Works very well for this application.

 

[gran]

What do you do if you need to an end grain to end grain glue joint that is strong. I make walking sticks and and want to splice sections together. My thinking was to insert a section of threaded rod to strengthen the splice and use epoxy for glue. Is that the right thing to do?

 

[Ed_McDonnell]

Malcolm - I'm now a believer in using Titebond for segmented turnings. I'm going to try it on the next one.

I hadn't thought about the "mortise and tenon" effect of the overlapping joints. That's an interesting way of looking at it, and of course you're right. I seem to recall that you might have even addressed the issue in your book. Time to pull it out and reread.

Ed

 

[Ed_McDonnell]

Gran - I've tried the following on my walking sticks.

For permanent joints using Titebond II:
(A) Inserted a hardwood dowel to strengthen the joint.
(B) Turned a tenon on one end and a snug mortise on the other.

Both of these ways have worked well. Of course, I live in South Florida so walking sticks don't get much of a workout down here.

For a non-permanent joint I used hanger bolts and threaded inserts with a butt joint. It worked, but I wasn't really happy with this. Next time I am going to add a small tenon and mortise as well.

Ed

 

[Ed_McDonnell]

Steve - Thanks for the link to the Michael Hosaluk site. I'll check it out.

Ed