Paddle blades will be filled with two part expanding polyurethane foam. This foam will add floatation and will strengthen the paddle blades.
This is two pound polyurethane foam. That means that after it has completely foamed, a cubic foot of the material will weigh two pounds. This is the material that is used for floatation in boats.
You will need TWO small cups each marked to measure one ounce.
It is critical that you mark exactly one ounce on each cup.
Carefully put one ounce of part A in one cup and one ounce of part B in the second cup.
Close both bottles tightly.
Return the containers to the flammable cabinet.
You will need your paddle blades (that have been glued together) the blade mold/clamp boards, and some small clamps - spring clamps work fine.
You will also need a stir stick that has been flattened on one end.
The flat end will allow you to completely stir the polyurethane and also scrape the liquids out of the paper cups.
If there are any lumps of glue on your paddle blades, remove them with a knife or file, or sandpaper.
Set the paddle into one of the clamp/mold boards.
The end of the paddle should be longer than the mold.
Place the second mold board on top of the paddle blade.
Add a few spring clamps to keep the blade in place.
A handscrew clamp makes a great stand, so the paddle blade stands straight up on a bench.
Pour all of part A into the cup that contains part B.
Work quickly! Scrape ALL of the liquid out of the cup!
Mix like crazy! No streaks, mix until you have a nice consistant color. YOU ONLY HAVE ABOUT 20 SECONDS TO MIX THE TWO LIQUIDS TOGETHER.
Pour the polyurethane into the blade.
Completely scrape the cup clean. Get all of the polyurethane into the paddle blade. The material will begin to foam 40 seconds after they have been combined so work quickly!
Rock the blade 90 degrees to the left.
Rock the blade 90 degrees to the right.
Stand the blade on a bench and allow the polyurethane to foam. Here we see a bit too much material was used! You only need one ounce of each part.
After an hour, remove the clamps.
Remove the paddle blade.