What is the syringe/resin method?

On another forum I came across a reference to using the syringe/resin method rather than filleting, in relation to building in ply using epoxy. I've not been able to find a definition. I posted a question but didn't get an answer.

Does this refer to butt joining play planks using a syringe to inject resin into the joint? If so what would then be done to reinforce the seam?

 

Not really for butt joints. If you're working with plywood you'll reinforce the seam with fiberglass. The fillet is a built up radius of thickened epoxy to allow the glass to make the transition (say from vertical to horizontal) without kinking. You can buy empty tubes for your caulking gun to do this but it's much cheaper to use the pastry bag method. I use 1 gallon zip lock freezer bags. Fill the bag with your fillet material and clip one corner then squeeze it out like frosting on a cake.

Does that help?

 

So that would be done after initally bonding the joint using a syringe to inject resin into the seam?

 

I take it this is the other forum you were poking, AK? http://www.neilbank.com/phpBB2/viewtopic.php?t=6019

I've only ever heard reference to "syringe/resin method" in the context of strip planking, in which case a syringe was used to inject epoxy between the planks once they were on the hull. I'm as lost as you are regarding the application to ply construction- joints in ply are usually either bevelled (in which case you wouldn't be able to get in to inject the glue) or butted up and taped (in which case the method Rick described would make more sense).

Perhaps the term is used in reference to lapstrake-style planking with plywood and epoxy? Just a possibility, I don't know for sure....

 

Yes, that's the one. I think you are correct about the strip plank application. I thought it might have to do with cedar strip but I checked Ted Moore's great book "Kayak Craft" and he actually does not suggest epoxy for between the strips, so I wondered if it had to do with ply planks.

I did some tests a couple of years ago. I joined a few dozen test pieces of ply with the grain in various directions, at various angles, using both unfilleted epoxy and fillets up to but not exceeding 50% of ply thickness, 3 mm and 4 mm samples. Then I tested the breaking point of the ply and the joints. I was surprised to find all the plain butt joints had 55-80% of the strength of the ply and a fillet thickness only 25% of ply thickness on one side only was enough to make the joint strength exceed that of the ply.

Based on that I suspect the regular fillet has very little to do with joint strength and everything to do with getting the glass around the corner neatly.

I do not use glass in my ply canoes primarily for environmental reasons and I also avoid epoxy when I can. I have been using cedar chine logs to reinforce the plank to plank seams but am interested in changing to a long-batten reinforcment applied after hull assembly (I thought the syringe/resin method was related).

In the long-batten method, a method used around 1880, a U-shaped metal strip was locked into rabbets along the inside of the seams to seal the joint. Incredibly difficult and complicated I imagine. I plan to strip off the inner veneer 1/4 back from the inside edge of the planks, assemble the hull using butt jointed seams, then epoxy strips of ply into the grooves thus formed. The strips will also have their glue-side face veneer removed so the grain on both sides of the glue is across the seam. It should be very strong, light and elegant looking, assuming I figure out the asembly problems that is.