Just curious , what pigments have you tried over the years that are added to Epoxy for color , and what ones have given you the best results that are easy to use that do not effect the physical properties or ( tensile strength ) .
OffShore,
I haven’t actually tested the differences in the way the pigments altered the physical properties of the laminate, but for pigments, I alway use the liquid ones found at US Composites.
I’ve tried a couple of different brands that offered pigments in powder form, but none of them were able to do what I needed.
Personal experience… US Composites.
-Corban
I’ve only tried two colors and I got them both from US Composites as well…both worked great!
Powdered pigments are hard to use. They really should be grinded into the epoxy resin to make them usable. This involves high shear mixing, then grinding and rolling.
So at least use a pigment paste, compatible with epoxy. (preferably the ones that are ground into an epoxy resin)
Keep in mind you are adding an extra amount of epoxy resin. Our resins are somewhat tolerant to deviations in mixing ratio, but the picky people should ask or know the amount of epoxy resin added, and account for that when adding hardener.
(as a side step: if you are going really high tech, where you are going for optimum results, you should also ask for the certificates of conformity, on which the actual epoxy value and amine value are mentioned. Calculate the mixing ratio from these numbers, not from the sales values. If you buy smaller amounts, it is doubtful the supplier can provide the certificates, though)
Other issues you might have with epoxy pigments are pigment separation, fisheying or other artefacts. In that case it is best to change supplier or at least notify supplier.
But we must consider ourselves Lucky that epoxy is very tolerant for other chemicals mixed into the resin. that is different in acrylic, pu and polyester.
Hah, I never even thought that pigment paste was resin with pigment added. I thought it was just… pigment. 
I guess what they say is true - you really do learn something new every day!
Thank you everyone for your replies , and to tell you the truth i have been using us composites pigments for many years now http://www.uscomposites.com/pigments.html but always searching for a better product considering …everyday is a learning experience …even at 61 .
For a wider selection Fibreglast can custom mix for you, over 900 colors. http://www.fibreglast.com/category/colorgelcoat
^^^ That is nice to know for future reference.
Hi, I wonder if is possible mix powdered pigments using ultrasound. Could it be sufficient for perfect mixing and to use these by infusion?
Regads and thanks
You can use these gel coats to pigment epoxy? I wonder if you can use it for your IMC too?
charcoal …
i grab a B-B-Q briquet and sand it down on a fine sand paper , this makes a fine black powder … so far its the best ive used for black epoxy