Becoming a convert.....

[J. Dillon]

to epoxy as glue. In repairing various glued joinery aboard my boat I will now use epoxy only.

Masts will be an exception as the Weldwood plastic resing glue holds up well for that use.

When building the boat 8 years ago I used resorcinol exclusively. Most of the joints held including all the plywood scarfs. BUT through the years my W. oak thwarts have been giving me trouble , opening up and letting go. I concluded that this was due to dew, rain, spray lieing on a flat surface inevitably worked their way to the joint, expanding the oak and forcing joint failure. Last winter I used epoxy exclusively to rejoining and reinforced with inlaid "butterflys".

At the end of this season all the epoxy joinery held but the older resorcionl joints show signs of failure. Maybe the butterflys did the trick.

My overall conclusion based on my experience is that where moisture is allowed to lie on a surface,( thwarts etc) Epoxy is best. Vertical surfaces like masts plastic resin works for me. I have had no mast or spar glue failure so far.

JD

[Ian McColgin]

Better living through chemistry.

[John Blazy]

Good man. Just don't drink it.
Epoxy 4Ever!!!

[Bruce Hooke]

Interesting.

What is worth noting is that your experience seems to be contrary to what I think is the "conventional wisdom" on epoxy vs. resorcinol. The usual take on resorcinol is that it requires very tight-fitting joints, tightly clamped together, and the air temperature while the glue cures needs to be relatively warm. Once cured, resorcinol is supposed to be the only (non-industrial) adhesive that can be used to hold together large pieces of wood that will be saturated with water some of the time. It can also withstand boiling water, so heat should not be an issue with it.

Epoxy, on the other hand, does not require tight fitting joints, should not be clamped too hard, and is a bit more low-temperature tolerant than Resorcinol. However, according to the Gougeon Brothers it should not be used to hold together large pieces of wood that will be saturated with water at times. In fact I believe they recommend laminating up backbones and suchlike from 1" or thinner layers. I believe they also recommend coating such laminations in epoxy.

I know you are not dealing with large pieces of wood, but the point is that, done right, resorcinol has the reputation of being able to withstand a good bit more than standing water. Epoxy should work fine for what you are doing (although there is considerable discussion about how well it works on white oak), but I would not discount resorcinol.

n.b., The reason I am using words like "reputation" and "conventional wisdom" is that I have not had much problem with glue failure with either type of glue so my direct experience does not provide much to go on. So, I am going on what I've read in sources like WoodenBoat Magazine and The Gougeon Brothers on Boat Construction.

[J. Dillon]

Bruce,

Interesting,

Is there a shelf life to resorcinol ? The batch mixed for the ply laminations was first off from fresh can or cans. When mixed batches several months later and used for thwarts it was taken from a can not so "fresh".

Another factor the outside portions of the hull were cloth and polyester resin sheathed ( BF before Forum, didn't know any better then)protecting the scarf below and above the waterline. This has stood up well with no signs of delamination. What did fail were r. joints exposed to all weather conditions including UV with only coats of varnish for protection. Some were OK and still are but stresed thwarts like for the mast failed in several places. Even a hair line crack admits water and rots the wood as well all contributing to failure of the joint.

JD

[John B]

I get the impression that there's a certain elasticity that you get with epoxy that you don't get with resorcinol. so a weathered surface, an exposed surface ,might do better with the epoxy.
?
I like the versatility of it anyway.

[Mrleft8]

Resorcinol definately has a shelf life. I once got a tyb of the stuff from the hardware store, mixed it up, laminated 24 walnut pieces into a form, and let it sit over night. The next day the glue was just as runny as ever, except in crusty little patches. I figured I'd done something wrong, and read the instructions again (never know, they might have changed the rules since the last time I used it...) There at the end of the instructions was a warning to check the manufacture date, and not to use it if it was more than 3 years old.... I looked all over for a date.... Finally,on the top, in smeared blue ink I found the date.... It was 4 years old....

[Bruce Hooke]

As Mrleft8 noted there is a shelf life to resorcinol, but the few months between your first use and your later uses seem unlikely to be enough difference to be the source of the problem. So, I am not sure why the resorcinol joints failed. Do you remember how well the joints fit together when you did the original glue up? For resorcinol there cannot be any visible gap.

One thing I am surprised about is that you used resorcinol for varnished parts. All of the resorcinol I have used was dark purple in color and stained the wood next to the joint the same color, thus making a very visible joint that would be quite prominent under varnish, especially with a relatively light-colored wood like white oak. I mention this just on the off chance that you were using something different from what I know as resorcinol.

Beyond that, I'm at a loss to explain the situation. There is always the chance that there is some reason why epoxy works better in this situation...

[Bruce Hooke]

Originally posted by Braam Berrub:
Bruce,
I always thought the caveat was RED oak, not white, the caveat for the white seems to be a new phenomenon, no?No, I think you have it backwards. Red oak is generally not recommended for use on boats because it rots very readily. However, it glues just fine with epoxy (and presumably resorcinol). White oak, on the other hand, is very rot resistant and for this reason and others it is great for boatbuilding, but there have been some reports of joint failures in white oak glued with epoxy. Whether there really is an issue with gluing white oak with epoxy is a never ending debate, but if there is an issue it is with white oak, not with red.