Science experiment with resins
Here in the United States we're in the middle of what is typically the hottest month of summer. Lately it's been in the 90's consistantly. This creates a rather large problem in working with fiberglass resins. Here's what I'm playing with. Typically you are given about 20-22 minutes of work time before resin begins to turn into jelly and is no longer usable when mixed with MEKP (catalyst) at 1% at 70 degrees. There have been times where Ihave to frantically mix a quick batch of resin to finish a hull because it "goes off" too early on me. With it being 90 degrees out, Ihave only about 12-15 minutes before it kicks, sometimes less.
Using a new brand of resin that I'm not too familiar with yet, I've set up an experiment using two different types of catalyst. Catalyst has different oxygen contents depending on the type. In this series of pictures, you see a sort of reddish mixture (#1), a brown mixture (#2) and a blue (#3), the control resin that has no catalyst in it. With it being 82 degrees outside, I've lowered the hardener concentration to about .75% where typically 1% would be used. Too low and it will begin to harden, but stay sort of "rubbery".
Two of these mixing cups have been catalyzed with different types of hardener. The red or #1 was catalyzed with the same type of resin I use when building full size boats using a chopper gun (the resin is sprayed into the molds along with the catalyst, mixed in the gun and air before it hits the mold). This reddish resin has a 3-4% oxygen content. The brown sort of color or #2 was catalyzed with the same amount of hardener with standard clear MEKP with an oxygen content of about 9% to 10%. The blue or #3 is straight resin out of the bucket, uncatalyzed. Placed there to see the color differences as the catalyst does it's work. The catalyst is altering the colors due the chemical reaction that takes place. The hardener is a peroxide that dues have some bleaching properties to it.
I've been checking frequently noting the time and viscosity every 3-4 minutes and stirring around just as I would in making a hull.
So far it's been 25 minutes and still looking fluid.
You don't want it going too long since wet resin may effect the gelcoat layer below and could tripe (wrinkle) the layer.
Keep checking back as I'll update fast as I can