Help needed from the experts

[baliano]

I'm building a boat from an old Science & Mechanics article circa 1950. The materials list calls both for "C" quality marine glue in one application and just marine glue for the rest. Anyone know what "C" quality glue is?

FYI, I'm using Resorcinol for everything I don't want to move such as laminated stem, glued-up transom, frame build-up and the frame to chine and clamp joints. I plan to use 3M 5200 for the sheeting to frames and keel. The part in question is the sheeting to stem, should it be Resorcinol or 5200 - I think 5200 but am not sure. That's where the "C" quality glue is called out. All joints are glued and screwed so the glue isn't the only structural factor.

[D'ARTOIS]

You are building according to an old method, so don't be surprised that you come across old standards. The particular "C-type" glue is most probably an indication for an old classification of chemical binding glues, where A = all Phenolics; B = Resorcinol; C = Urea; D = Melamine; E = Plyurethanes; F = Epoxy's etc.
In the early '60s till mid '80's the Resorcinol-Phenol-Formaldehyde like CIBA-Geigy's Aerodux, one of the most popular glues for long term binding.
Now it has been replaced by epoxy but at that time it was an excellent industrial glue. I used it myself a lot for all kind of applications as it is in some cases a better glue than epoxy.
Resorcinol-Phenol-Formaldehyde is also known as "Bakelite" - as I believe it is still available under the brandname Aerodux and Aerodux 500.

[baliano]

D'ARTOIS, thanks for the information. I've had no luck finding any of that through the on-line resources.
I decided to go with Resorcinol because it appears to have the right structural properties for those joints and it's readily available from True Value hardware. I'm using it to laminate the stem, edge join the transom boards, for the butt blocks, the frame lap joints and the plan calls it out for the side to stem, transom and chines. Like epoxy, there must be a glue line but only a minimum of 0.005" thick. Everywhere else it calls out either screws or clenched nails only or screws and "marine glue" with a layer of glue impregnated fabric as in the bottom panels to keel and chines. For those places I'm using 3M 5200 and screws thinking the 5200 should eliminate the need for the fabric. I haven't decided yet if I'll use 1/4" thick butt blocks with rivets or clenched nails and Resorcinol or go with 1/2" to 3/4" thick blocks and screws with glue.

[D'ARTOIS]

I hope you're still on. Keep the gluelines as thin as possible as the waterparticles from the glue dissappear whilst curing, resorcinol looses volume during the hardening-process. Make all joints fitting well and do not leave gaps like you can do with epoxy. Another hint: never use epoxy and polyurethane together, those two types of glue do not go together - the epoxy, even cured is going to react.
Good Luck,
Brien Gilroy D'Artois

[baliano]

The Resorcinol is a two part resin not the old Weldwood water-activated stuff. DAP calls out a min .005" glue line to prevent starvation. The joints using the 5200 might be starved but the 5200 is for sealing more than structure, the screws provide the strength. I pretty much had my fill of epoxy when I built a stitch and glue skiff by Bateau, the FL14.

[D'ARTOIS]

You should be pretty ok then....http://www.boatdesign.net/forums/new...643&noquote=1#
Smilie

[tonyr]

D'Artois, what do you mean by "they bite each other" (epoxy/polyurethane)?

I made a strip built sail/rowing boat using PL Premium between the strips (and for other structural purposes), coated the boat and all glued components thoroughly with fibreglass/epoxy in the usual way, and have used the boat intensively for the past four years. I have also carried out glue durability tests involving the two of them, with satisfactory results (cold water only - a boil test seems redundent here - we don't have that temperature in this area!).

There have been no problems at all.

Comments?


Tony.

[D'ARTOIS]

What I meant to say was donot use pu glue on a epoxy resin. That's all. We had an experience that when glueing stringers in a sailboat, for costs reason only we used pu glue. The result was that we received no bonding and a strange chemical reaction between the pu and epoxy.
Thertefore, I warn for such application/use. Of course it depends on formulation as well as the pu glue as the epoxy. I realise that now.
regards,
Brien

[tonyr]

Interesting. It may be that some PU glues should not be glued to epoxy, but perhaps the other way round may be O.K. Probably room for a Master's thesis here!

Tony.

[Bergalia]

In timber construction (some fifty or more timber craft) I've always sworn by Cascamite. Comes in powder form with acid catalyst. Mix powder with water to syrupy constituency. Apply to one section of timber to be joined, and brush on the 'acid' to the other section. Wear gloves and mask. But the Cascamite is saltwater proof and makes a stronger bond than the timber itself. (No - I am not employed by Cascamite.)