Experimenting with Epoxy

So while I'm taking a short break from the vacuum bagging fin project, I decided to play around with just the epoxy resin itself a bit to gain more experience working with it for future fin and board projects.
Please take all precautions with working with epoxy- I used nitrile gloves and safety goggles and made sure I had a protected working area.
I used a little silicone pinch bowl, kind of like you'd use for salt and seasoning serving, but it works great for molding epoxy since it can take heat. Obviously, I'm not using this for anything else, so it's bright green, like my other silicone tools I don't use with food (kind of a nice tip to use).
I measured out a small amount of mix, 2 parts resin, 1 part hardener, (just like in the glassing project), and I even added one drop of green food coloring into this mix just to see what would happen. I also got together some small shells and sand to sprinkle inside.

Little silicone bowl for mold, shells, food dye, measuring cup and stir stick

I decided to watch the time from the start of mixing the resin and the hardener, since this was supposed to have a slow kick time, and unfortunately, we didn't have that happen during the fin vacuum bagging.
As I mixed the epoxy with my wooden stick, I noticed that the food coloring dye seemed to seep right into the wooden stick! But, as I kept mixing, I noticed the dye leaving the stick into the mix and turning a pleasant, light shade of green. I poured the mix into the silicone bowl, added the shells and sand in, and kept mixing with the wooden stick right in the silicone bowl.
The mix seemed to have some viscosity, but not quite as much as honey. I kept stirring, one, to ensure a good mix, and two, to try to keep the little shells and sand "floating" in the mix. I stirred for quite a while, but the epoxy never kicked gradually enough to hold the sand and shells off the bottom of the bowl so I kept mixing to make them suspend, then BOOM! It kicked all at once and I was barely able to get the wooden stick out before it started to rapidly harden.

Wow! That kicked fast!

The color of the resin as it cured, turned out a nice Coke bottle green- in fact, the bottom of the measuring cup that still had some epoxy looked like a pretty nice color.

Some green epoxy curing in the measuring cup

I know it takes at least a full 24 hours for this epoxy to cure, but I wanted to do a little check of the outcome of the color this morning. Unfortunately, my sand and shells settled right to the bottom, so I won't be working at Twombly's Resin Creations anytime soon, but I was most interested in the color. Here are some pictures I took:

As you can see, the green came out pretty strong, and a nice color with only 1 drop of food coloring. Outside of the sand settling, and the uneven top surface (I said I barely got the mixing stick out, and I wasn't kidding), I think it looks kinda cool. The bottom- that is not blocked by sand- looks cloudy, but I wonder if sanding and or a gloss coat would help that. I've been told by expert glassers that cloudiness is a challenge when working with epoxy resin.

For this experiment so far, here's the data:

Amount Mixed: 4 fl. oz.
Kick Time for "Slow Cure": 12 minutes
Ambient Temperature (Garage): 84 degrees F, measured by in garage thermometer
Humidity: 90%, as reported by the Weather Channel at 8:30 PM

Amount of green food dye added to mix: 1 drop

Now, I'd like to see how the color holds up to the bright sun. I'll update on this post if I find any changes.

UPDATE 8/18/11: At the 40 hour mark after the start of the experiment, most of the epoxy has cured, but just a little bit on the top that was over the silicone bowl lip still feels a bit sticky to the touch and has not fully cured. I have left the epoxy in the midday sun to see if will cure any better and observe and color change.