System Three epoxy

According to the System Three website, 5 Minute QuickCure is not waterproof, only water resistant. Typically, 5 minute epoxies have significantly less bonding strength than slower curing resins. You should call System Three and discuss your intended use with them.

If you compare apples, the 5 minute epoxy is much more expensive at $220/gallon kit, where S3 general purpose resin is about $120/gallon kit and West System at $140/gallon kit.

I've only used West System for larger epoxying projects. I do use Quick Cure and S3 T-88, but only in certain situations.
 
I generally have some of the System Three 5 minute epoxy on hand as a general use glue for small tasks, when I want a quick cure. I have found quite satisfactory, generally measuring the 1:1 ratio by eye, squeezing out blobs onto a scrap piece of cardboard and mixing with a stirring stick It is fairly thick -- I have never felt the need to use any additive. It is described as highly water resistant, but not water proof -- this would be sufficient, I think, for repairing stems, at least the upper part of stems not usually submerged. I don't know that I would use it where extremely long periods of submersion are expected. I have not had any problems using this stuff.

I also generally have some System Three T-88 on hand for general use, for larger tasks when more time is required, or when I just want to work at a more relaxed pace. For a job where the close fitting of parts is fussy, I prefer this to the 5 minute stuff. On the other hand, if the fit is clean and easy, with 5 minute stuff, you can often simply hold together two parts being glued, avoiding clamping (although 5 minutes can seem much longer when you have to hold something together with no movement).

T-88 is similar in thickness to the 5 minute stuff, and again, I have not had to use thickeners or additives (though I did add graphite for color on one repair job). Both are thicker than West 105 stuff, which I have used when I needed its consistency when applying a kevlar patch to Royalex, and where I wanted no question about its use on something to be submerged for some time.

I have also recently been using West's G-Flex, which is supposed to be less rigid than most epoxies, and is supposed to be better for difficult woods such as white oak. I have not had an opportunity to observe any such differences or advantages, but it certainly is a good general-purpose epoxy.

For splicing canoe stems, I presume the joint will be somewhat scarf-like, and so will be partially end grain in character. I would be concerned that even during during the quick cure of 5 minute stuff, the open grain of the wood might suck epoxy into the wood and away from the joint faces, leaving you with a glue-starved joint. For such a joint, I would use a slower-curing epoxy -- coating each face of the joint and allowing the wood several minutes to absorb as much of the adhesive as it will, and then re-applying more epoxy just before clamping. Perhaps this is being overly careful, but why run even a small risk just to save a couple of minutes?

For a stem repair, I would use either the T-88 or G-Flex (or West 105 with appropriate hardener and thickener) in preference to any five-minute product.

The repair is meant to last a long, long time in an area that is not easy to reach or repair if there is a failure -- what's the rush? And the a 1/2 pint or pint of the 5 minute stuff is about the same price as the same amount as the other stuff.
 
For Years I have gotten my epoxy from Douglas & Sturgis in Richmond, Ca. and have had good luck with it, what I get has a 45 minute pot life with 24 hour cure time and it is Chrystal clear. Their 1 gallon kit I believe is only $98.00 so that is a lot cheaper than some of the others out there.
 
I like RAKA products. Used their 127/350 on my wood strip 9 years ago and after MANY HUNDREDS of miles, its still going strong
 
I'll add another cheer for RAKA, and their 127/350 non-blush hardener!!

Ever since my first conversation with Larry, I've used nothing else.

The 6oz cloth comes rolled, and without flaws.

Jim
 
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