Titebond III testing

hooked and bridled scarfs in the keel timbers tree nailed as always with tapered heads and some form of glue

what form of glue being the key question
I guess Im stuck with epoxy but given the industry it comes from I just have this innate distrust of the stuff
might as well be asking the tobacco industry about lung cancer

 

Just stay away from the typical aliphatic amine curing agents and you'll be fine. Many adhesive type epoxy formulations use a polyamide curing agent. The polyamide family is characterized by very low toxicity/sentization. They are generally undesirable as curing agents for laminating resins as they tend to be thick and somewhat low in AHEW (the objective test for curing agent 'potency') which means you need a lot. Typical mix ratios are between 1:1 and 2:1 resin/curing agent. The typical unmodified viscosity will be about like cold honey. A small amount of thixotropy will get you a consistency like peanut butter, ideal for adhesive bonding apps. The cured resin also is not terribly hard but instead somewhat rubbery and very tough. These are all desirable properties in an adhesive. They do not usually give you a high Tg, even with ETC or post curing. EMI-24 can get you everything (low tox, high Tg, thin visc., low mix ratio) if you can put up with extremely loooooooooong cure time at room temp (measured in days) or can use elevated temp cure (ETC).

Jimbo

 

Pl

We've used PL premium on all the wood boats we've built ( 5 ). they are all trailered and don't stay in the water. no glue joint has ever failed. The joints are glued and fastened, but the fastening is more about clamping than structural strength. These boats are cheap builds and not expected to live more than ten years so my conclusions my not be valid for an heirloom quality boat. Materials used are luan ply, white pine and construction grade spruce. We treat the luan with a restoration wood hardener and it lasts very well for an inexpensive material. My current project is a skin on frame rowing boat. It uses white cedar gunnels, laminated yellow cedar stem and stern post and ribs with deck grade mahogany for the stringers. Everything is fastened with Pl premium and a minimum of small brass screws. We'll have to see how it stands up to the streses of very hard rowing.

 

I dont mind the curing time at all Jim, the keel assembly can sit while I do other things. Its the durability that Im interested in. The type of joinery Im planning for each area is basic glueles type interlocking stuff, obviously depends on the area but the joint would normally be glueless so set up time is irrelevant. Only thing Im curious about is if the pins will heave out of there holes before the glue sets up. a glueles pin will stay put but some glues are just terrible and you end up standing there watching so see if the pins start rising on you. Maybe I just wont glue the pins cause once moisture begins to seep back into the wood after its kiln dried those pins are going nowhere.

Whats this EMI-24 stuff
Ill have to look that up

Not sure, I guess most people haven't seen a bridled hook scarf, thats another joint that isnt going anywhere glue or no, that level of jointery being rare even in the finest of yachts. I dont think set up time is a big issue

Thing to remember is that so far ( Im still considering Black Locust ) the keel timbers are going to be white oak and gluing it can be tricky. So the glue needs to be WO compatible. Even if the keel isnt WO there will be lots of components that are. Tragic reality is that T3 works fine on WO if it just didnt have this funny habit of popping loose, well that and nothing sticks to it once its dried. I need the build to be serviceable as well as functional


So Jim what do you have on this EMI-24 stuff
I want longest possible durability and the industry is strangely quiet about that

 

3M has a marine division and I have contacted them by email and always got answers back. My last question was the best adhesive to glue an aluminum boat together without bolts or screws. I got a very detailed message back with instructions. Goggle their web site. Tell them what your doing and your needs.

 

The 3M 2216 (clear) is an awesome epoxy structural adhesive. It's modified with CTBN rubber and is unbelievably tough and fatigue resistant. I have tried to beat a joint bonded with 2216 apart with a sledge hammer and was unable and that was on cast aluminum. I repaired a broken Red Devil paint shaker with it once (the part that clamps the cans) and it lasted for years. It never actually failed; I just got rid of that old shaker and bought a new one. So 2216 does not mind cyclic loading.

Here's the dope on EMI-24:


View attachment EMI-24 PDS.pdf

View attachment EMI-24 SDS.pdf

Jimbo

 

yikes
am I converting that correctly

stuff says its got 64 mpa tensile strength
that converts to 9284.41 psi or did I do something wrong with the conversion

way more than Ill ever need given that White Oak has a tensile strength of 13,900 psi
and Black Locust is 19,400 psi

hows its compatibility with WO

once again they list shelf life of the components but not the expected working life of the glue itself
what is up with the closed mouth policy concerning the life span of this type of glue. I thought Ild find some info eventually but the more I look the less I find.

has anyone ever dismantled a old epoxy glued wooden boat
if so what was the age of the build and what was the condition of the epoxy

B

 

there is a graph but it wont come up
basically at 10^6 loading cycles laminated wood is vastly superior to all but carbon fiber in its ability to maintain a higher % of its ultimate strength and it is marginally superior to carbon fiber at that, however at 10^7 cycles it is marginally inferior to carbon fiber. Would love to have seen this graph with solid wood included

the wood considered was douglas fir laminated in epoxy as compared to aluminum carbon fiber steal and glass fiber reinforced

 

With a normal wood joint it's the across-grain strength that counts, and that's about 10x less than with-the-grain.

white oak 1300 psi
white pine 550 psi
southern longleaf pine 1200 psi

I would have thought that, with epoxy adhesives being available since the 50's, by now someone would have reported any deterioration. I suspect that the cross-molecular linking would continue at a low level making it stronger with time. Of course, it would have had to be protected from UV all that time.

 

I have only spent a few hours looking but so far have found no research on the degeneration of epoxies

Ive got an original copy of Wood A Manual For Its Uses In Wooden Vessels
Bureau Of Ships, United States Navy 1943
its got the strengths measure in about twenty different ways
all of which are highly dependent of moisture content which is also listed
on average white oak or black locust seems to be the winner for frame construction and workability of the wood

 

Black Locust has a better sounding name than white oak. So it gets my vote.

 

Im starting to like the stuff myself and I can get it cheep from a mill in Pennsylvania

 

Epoxies are generally extremely resistant to degradation due to environmental attack, except from UV light. If they have an Achilles heel, exposure to UV light would be it.

Jimbo

 

Live oak is a better choice for framing, then either white oak or locust.

 

live oak is great for certain areas of framing, like knees and floors maybe horn timbers and stems depending, basically whatever requires consistent strength through sawn pieces; but for frames and stringers, long straight keel members and deck beams Im better off with WO or Black Locust as its straighter grains and longer lengths will come in handy in these areas. I might go with tulip poplar for the planking instead of red ceder since its a little stronger and I can get clear grain poplar for half what I can get #1 cedar for. and if the Locust people actually come through for me ( I have never used that mill before) then I might even go with locust frames as well. Not sure who suggested the stuff but it was a great idea, the more I look into it the better I like it.

Went to a party tonight and frankly had a rotten time. The limo couldnt hold everyone and broke down, the burlesque show was full of fat people, and the restaurant was about a hundred degrees. Not sure how you could plan it all out so badly but dam if you dont know how to plan a party ask for a little help
only saving grace was I wasnt paying for it so I guess they can screw up all they want eh

B