Adhesives and White Oak

[Bill Adamsen]

Creating some scarfs with White oak rails on a dinghy and looking for techniques folks have used for gluing and their opinions of how those held up. I was going to use a 12:1 and hand sand with a board to get a flush tight fit (rails are curved).

What I've done in the past is used epoxy, and no special preparation, and that worked. Some are still perfect after 15 -20 years or more. I've also used resorcinol - but realized I currently don't have any. Is there special prep I should be considering if I think the area is likely to be under some stress?

Thanks

[Bill Adamsen]

Should I be prepping the surface with MEK, Acetone or Lacquer thinner ... if so, how far in advance of the glue up? For the glue up should I coat with a high penetration layer and then with a thickened layer and lightly clamp? Perhaps I should just do a few test glues and record the breaking failure points.

http://www.westsystem.com/ss/surface-preparation/

[Jim Creech]

Do as West system recommends for precleaning. For bonding I would continuously apply the epoxy until the wood will not accept any more then thicken with some milled fibres, align the parts and lightly clamp. You need as much penetration as possible as the tannic acid in white oak and epoxy don't play all that well together. Please don't ask how I came to know this!

[Mac McQuinn]

Bill,
Since the rails are above water level and not submerged, how about using TB3 as an adhesive? As Jim reports white oak and epoxy don't play well together, TB3 might be your answer. I've done quite a few fit-ups with Q/S white & red oak along with marine ply and Sitka spruce using TB3 with good success. JAT
Good luck,
Mac

[Jim Creech]

Good idea Mac! Because Bill was talking epoxy I didn't even consider another type of adhesive.

[Quinn McCarthy]

Dido on Mac. Another vote TB3. Easier to prep and will last a long time. Cheaper too.

Quinn

[Rich Reid]

Just to stick my oar in, I have glued up and laminated a lot of white oak, including the last time I used West Epoxy with it, laminating 3/8" X 2" strips for curved (crowned) cockpit deck beams on a 37 foot wooden sailboat over 30 years ago. That time per Gudgeon instructions we washed the surfaces with acetone, then after planing them flat, sanding them rough with 50 grit "priming" them completely with epoxy resin, then glued and clamped up with epoxy thickened with milled fibers and cabosil (colloidal silica). However there was still a lot of delamination. Ever since then Resourcinol has been my go-to glue with oak (and teak) although it is now hard (or impossible?) to find. Purple yes, delams no. I do use epoxy just fine for everything else, including mahogany, cypress, juniper and presently replacing natural crook knees in a 36 ft boat with laminated angelique. See FB "Saving Sylvia ll".

[Bill Adamsen]

Folks - I did the glue-up using epoxy later in the summer and then pushed the boat outside to make room for other projects. The hull was so flexible without rails that I felt I had to get rails and at least one seat into the boat in order to get the structure required to grind off the paint.

I pulled it back into the shop Friday thinking I could finish grinding off the layers of paint and gelcoat and get it ready for refinishing. Obviously a few months of sitting does not a comprehensive test make. But I thought I'd show what the results are anyway. I layered White oak (bends easily) and Honduran mahogany (stiff) to create a continuous lamination. The idea was to make it look like just Oak from the outside. There are several other laminations on the boat for joining previously steam bent sections. So far everything has held up well ... both the Oak->Mahogany and the Oak->Oak joints. The finish is just two layers of WS207 ... not UV protected yet. Sorry for the crummy photos ... the light wasn't very good.

The rivets are countersunk flatheads I purchased from Faering design. Going through a tight hole in the glass is tricky ... I lost about 15%, but kept to the spec for hole sizing.

[Peter Almgren]

It looks very nice. What are you planning to finish the hull with?

[Bill Adamsen]

Well if I ever finish grinding off the old gelcoat ... I expect a fair amount of fairing and then since the boat is dry sailed, I'll use a topside paint. I bought Total Boat (first time using it) and am planning to paint the topsides "Sea Foam" and below waterline (and perhaps transom?) "Oyster White." I'm doing the boat for my daughter and so I'm going for "pretty colors."