Mica powders

[RDHals]

This is for the casters out there. I've started using a different brand of mica powders to color my resin lately, and I've noticed a problem. After the casting has cured and I take it out of the pot I see spots, not many but some, where it looks like the mica powder hasn't mixed well in the resin. Kind of just dots' of color. I use Alumilite and I store the resin in a fridge, to keep the humidity down and to give me more mixing time. I would say that I spend at least 10 min per pour just mixing resin, and mixing mica into resin. I constantly scrape the sides of he cups as I mix. So I'm pretty sure the mica is getting mixed in enough so the only thing I can think of is the mica powder. So here's my questions:
1. How do you color your resin?
2. Have you ever experienced the same thing if so how did you fix it
3. What brand of mica, if any, do you use?

Thanks ahead of time
Russ

 

[Kenny Durrant]

I use different brands and haven't experienced those issues. As of now anyway. You mentioned refrigerating your resin and stirring for several minutes. Here's what I do. I get the molds ready and put them in the oven to warm them up. If it's tube in I put the whole setup in to warm up. I use an electric candle warmer to warm the resin. I weigh up the B side, the thickest one, and warm up but not too warm. I go by feel so I don't know a temperature. I just want to lighten the viscosity a bit. When the molds are ready I mix the mica in the warm resin. When I'm satisfied with the color I add part A. Mix a few minutes and pour it in the mold and then the pot.

 

[Hippie3180]

Probably the most common micas used with Alumilite is Eye Candy brand. With that said, I have a few that are Eye Candy and a lot that aren't from a previous project. I keep my Alumilite Clear Slow in my work space that stays coolish. If you're mixing very well and your Alumilite is fresh I would wonder if your mica is contaminated with something.

 

[mredburn]

If I remember right one of our members wrote an article years ago on this. Your mica is clumping and not mixing into the resin. You may need to add it to Either the A or B side before mixing the two. You may need to add it slower. Ill try and find the article. Did your old supply of mica have this problem?

 

[JohnU]

I keep my resin cool for storage but not mixing. The only time I cool down resin is if I'm pouring "white" and need more time to mix individual colors because it has a 2-3 min working time. For Clear and Clear Slow I always warm side B to around 90° prior to mixing. It will mix easier and quicker. I also use a modified spade bit in a drill to mix. It's much easier than storing by hand. I ground off the tip and the side points so it doesn't puncture the mixing container. The cold resin may be your issue. It might be too thick to distributed the micas. I use all types of micas, eye candy, pearlex, generic…. The only time I've had issues is using makeup to color resin. There was just too much additive in there with the micas and didn't break down in the resin.

 

[RDHals]

Thank you a for your replies. I've attached a couple of pics so you can see what I was talking about. You can see the orange and black dots that look to me like unmixed mica.