Problem With Black Castings

[crokett]

I had to toss a blank last night. It was a black/copper Pearl Ex swirl but the black didn't seem to be opaque enough and I could see the tube in a few spots. I haven't had that problem with other opaque colors. Did I not use enough color? Is that just what black does? I painted the blank but the tube was a tight fit, I guess it scraped some of the enamel off. Is there a way to save this, maybe paint the outside of the blank?

 

[jbswearingen]

By "black", what do you mean? If Pearl Ex Carbon Black, you'll need to add more, likely.

What pigment are you using? I did Carbon Black and Red Russet, back painting the tube AND the blank and got this:

 

[crokett]

It is a black opaque pigment, not PearlEx. The brand name is something called Castin' Craft. My wife got several colors a month or two ago for something for the kids and never used them. So far I have only had a problem with the black. I am wondering if I just need to use more of it.

 

[jbswearingen]

That's what I suspect.

 

[PTsideshow]

Yes for depth of color (opaqueness) with some colors whether paste or liquid dyes more is some times needed, but you can reach a point that the chemistry of the resin mix is altered were it doesn't set the proper way.
:clown:

 

[BSea]

I use dye a lot, but not for black. I use black mica powder from coastal scents for all my black casting. Even though it's almost opaque, I still recommend painting the blank and/or the tube just to be sure.