Dinghy cruising a John Welsford navigator - oar building update 3

Slightly colder - around 11C today but impatience set in. Lets hope everything cures OK.

So, using west epoxy 105 resin with 205 fast hardener.  Using the 1Kg of resin pack and mini pumps 301.  Basic rules about epoxy bonding as I understand them are below. It is many years since I have used the stuff so I had to do a little reading around.

First I prepared the wood by marking it out in 40cm sections and then rough sanding it with 80 grit paper and then a wire brush to rough up the surface. the marking out in sections helped me remember which bits had been sanded and not. It is soft Douglas Fir and so a good surface was established for the epoxy to bond to.

Then came the epoxy mixing in a plastic pot. I checked the rules once more on the can sides and leaflet. Because I am paranoid and wood and epoxy are costly!

1. you can use it between 4C - 28C
2. mix it in small batches and get it into a tray quickly so the heat dissipates rapidly and the open working time stays longer.  
3. Mix thoroughly so that all the resin and hardener are truly mixed together.
4. Wet out both planks to be bonded with a very thin layer first. Working at around 7C, I  had an open working time of around 20 minutes or so. I used a foam mini roller to spread put the epoxy in thin layers on both planks

         4. I then mixed another batch and added 403 microfibres to thicken the mixture. 

         5. This was then spread across one plank only and the two planks were then joined.

         6.  I then did steps 1 - 5 again with the two plank faces and added the final plank. 

          7.  I had already prepared the clamps and had opened them to the correct gap. They were

               added at 8 - 10" intervals both sides. I didn't bother to use plywood pads below as much

               of the wood where they attach will be cut off when I come to shape the oars. The trick is

               to clamp them with sufficient pressure without squeezing out all the epoxy. Easier said than

               done. 

             8. I cleared up and removed runs down the sides after a few hours when it became rubbery.

             9. I'm now leaving the boards for around four days so they can fully cure. 

Further tips:

How I wished I had put down plastic sheet under the boards and along the garage floor. Dribbling epoxy went everywhere and its the devils own job to clear up. 

I should have used a couple of clamps over the width of the boards to stop them initially sliding about - would have made life easier. 

Next thing to build is a plywood jig for marking out the octagonal's on the oars when they have been cut to size in plan and elevation dimensions.