I have been a woodworker for a long time and one of the magazines I like the best is Fine Woodworking. When I started doing my research for the correct glue to use on white oak I naturally went to Fine Woodworking to see what they had to say. Thought the article I found would possibly be of interest here so here is the link.
http://www.titebond.com/Download/pdf...urGlue_FWW.pdf
BUT FOR DISCUSSION let me throw in some things that imco have to be taken into account for woodwork on a boat.
NEVER USE AN "INTERIOR GLUE" ON A BOAT.
White Oak in lamination cannot be glued with any glue used in the Fine Woodworking test.
Titebond 3 so far as I know has not been tested for white oak bent laminations glued up under tension. Nor in a wet/dry cyclic boat environment.
I have HEARD for years that boatbuilders ("conventional wisdom") will not use any yellow glue because it will eventually creep because it is hygroscopic in the damp. The FW test is primarily for wood joints that will live in a fine moisture controlled frufru situation.
A glaring omission from the FW test is water resistant plastic resin glue you catalyzed with water. It has a long open time, requires clamping, and has almost no glue line. Commercial tillers use it.
Titebond 3 (not yellow but grey) seems to be a different animal, but will need testing for veneer laminations and other wood-to-wood gluing in damp.
The conventional test for glues used for wood-to-wood bonding is a four hour boil test!
There is only one glue that survives this test 100% and that is Resorcinol. This glue requires milled surfaces and pressure clamping, no gap filling, THAT I have always taken to mean very light sanding to deglaze surfaces.
Gorilla Glue has no place on a boat. I have witnessed a number of failures used for furniture. While epoxy is a glue, polyurethane* is not!
I have had my own failure with T-88, and wrote extensively here about my experience with it. My conclusion is that the best off the shelf 2-part STRUCTURAL EPOXY ("tropical wood") is made by Smith & Co.
I have used this glue for white oak laminations (untested) and noticed some starved joints. Imco it is very difficult to squeeze this product out of a clamped joint, BUT it seems to be possible and therefor is not used for bent in form lams.
I have some suggestions which have been reiterated elsewhere. Imco no trustworthy lamination can be made with ANY glue on white oak. Except Resorcinol.
And it may be that the oak must be pre-treated/de-natured to remove tannins.
I epoxy-laminated a white oak beam for A338. I put an epoxy saturated layer of fiberglass between each piece of oak in an attempt to not starve the joints. I also attempted to remove tannin oils with solvent and roughly scoured the faces with 40grit. Years now later I see some tiny separations appearing and decided to bolt the whole damn thing together - which I've described in the Gallery.
I'll always worry about it. Wood will ALWAYS move in a cyclic environment. In my case I have isolated the wood pieces with a hard non-moving material. Doesn't really work. So you see what happens using Resorcinol - there is NO glue joint. Can only describe the phenomenon as a chemical bond - rather than a secondary mechanical bond provided by ALL the other stickums.
WITHOUT QUESTION, it would be much better to bandsaw a new strongback out of solid white oak timber!!!
Ultimately, the best bond/attachment is always made with bolts and screws.
Maybe we should see glue as only in a support role for metal fastenings and as a caulk to keep moisture out of seams.
For wood-to-wood furniture work on the boat my gut feeling is that Titebond 3 can be used.
It is easy to use, there's no mixing, it's water cleanup, and hardly a glue line. Mahogany and fir and plywood, conventional joints like the open joints used in the FW test. Only an assumption.
Would like to see anecdotal evidence on this. [EG, what did Larry Pardey use for the extensive interior woodwork in Tallesin?]
For attaching wood to fiberglass there is also no 'boil test' guarantee that you will get bonding. Therefor fillets and tabbing must be used. And that has to be done with epoxy. Could say this method is an attempt to OVERPOWER the wood.
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*Polyurethane tube rubber is another discussion.
Last edited by ebb; 01-26-2010 at 01:10 PM.
If a wood joint stood a chance of being exposed to constant dampness I don't think I would use anything but an epoxy or resorcinol, as much as I like Tite-Bond III. But cycling between wet and dry states will ultimately destroy any joint, regardless of the glue. We all know that maintaining the varnish or paint helps things last.
Resorcinol has a funny taste if I remember.
Resorcinol has the track record and is the only glue that will take extremes of wet and dry, heat and cold.
Epoxy has very limited exposure outside and has been known to disintegrate even if maintained. See the renovations that had to be done to all those traditional finished cruisers from 20/30 years ago - especially anchor platforms and bowsprits.
Epoxy glue is an interior glue! It can't take heat (it softens) and can't take cycling because it doesn't move. If you seriously have to keep exposed wood together, there's definitely 5200.
Last edited by ebb; 01-26-2010 at 01:25 PM.
So, er, uh, what are you guys sayin' here? My mast beam is going to fall apart? I haven't noticed anything coming undone voluntarily yet. Is 'yet' the operative word in the works here? Crimony! I guess Ebb's lead in holding the beam together is a fix I could apply easy enough, but, I'd rather think it wasn't necessary...crud. Oh well, one step forward and you know the rest.
Resorcinol's rap is that of being harder to work with than epoxy. You can be sloppier with epoxy. Garden variety epoxies may have some trouble with UV and high temperatures but are tested as being stronger than resorcinol. And there are epoxies that perform well at higher temperatures. What are they making the new Boeing 787 from?
I agree that the best strong back is a band-sawed piece of solid white oak. Preferably from an old gnarly hanging tree.
Ben
Well,
Resorcinol is a wood specific 'bonder'.
If you were gluing exterior mahogany rails up from strips and scarf joints there is no other glue. When you glue coaming blocks and winch islands up with epoxy you will have separation at some point. And as I just said if you have an epoxy glue-up like a bowsprit and/or teak anchor roller they are guaranteed to come apart. I don't know how long it'll take, but the more heat and wet/dry cycles they experience the sooner they will come apart.
I'm talking about pieces of wood brought together into a structure.
Epoxy IS definitely more versatile. You can glue wood together and seal it with the same epoxy. You can fill gaps and fillet, you can laminate fiberglass onto wood and foam panels with the same stuff. You could probably do a barrier coat on the hull with it. But, by definition, you only achieve a mechanical bond.
I hesitate to use that term here as the adhesion is mechanical but not a BOND. There is no comparing here with Resorcinol which can only glue flat pieces of wood together FOREVER. It has a bad rap because of its short open time and need for high clamping and controlled temp.
If I had been more comfortable with Resorcinol I might have done A-338's strongback lamination with it. I felt I couldn't do it within the short open time required.
It is entirely possible to put together a new rudder for the Ariel/Commander with foam and glass OR plywood and glass using good epoxy. There is always the chance that the epoxy can separate from the wood or the foam.
You have to take this into account when designing the rudder. But this is not gluing wood-to-wood. The whole intent is to encapsulate the wood - and it sometimes doesn't work. Exposed, varnished wood swells and shrinks. Epoxy glue-line is more or less non-shrink and hard. Wood wins.
If you had to glue wood-to-wood together for underwater use (like the original non-encapsulated rudder) Nobody would spec epoxy. It's possible to butcher-block and pre-bond pieces together into 'planks' with Resorcinol for cutting the shape and use polyurethane or polyether for gluing/caulking edge to edge planks. Most people these days would then SEAL the wood with a thinned epoxy, then attempt to waterproof with a polyurethane coating (or whatever new comes down the everchanging chemical pike.) Or go right to bottom paint. Imco that's conventional wisdom.
In every case epoxy must be protected with another coating. Even a novolac needs UV protection. Pigmented epoxy coatings/paints will chalk and breakdown. There is no comparison with LPU coatings Even polyester coatings will outlast epoxy coatings. On those winch islands use a clear coating with the highest UV rating you can find. That'll help some.
The chemistry keeps changing. There are new combinations appearing: epoxy polyesters. epoxy urethanes and resorcinol epoxies, and ETC for both adhesives and coatings. Quite amazing.
But at the moment everyday epoxies that we buy really have limited use on the exterior of a cruising sailboat.
Please, I work with these assumptions on my Areil. If there are developments or stuff I've forgotten (more likely every day), please clue me and the boat in! We both depend on it.
The limited info about glues and coatings that I work with IS ALL conventional.
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Laminating white oak w/ Resorcinol - The WoodenBoat Forum
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For unstressed gluing somebody by now must have tried using CLEAR polyether or a silyl-urethane. !NOT SILICONE! Also sold as Hybrid Sealant/adhesive.
This is a one-part, low odor, 100% solids, long life, moisture cured, always flexible synthetic rubber in a gun tube.
Worth experimenting - like gluing a stack of mahogany blocks together and boiling them for awhile!!!
Last edited by ebb; 01-29-2010 at 08:10 AM.
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