black colorants

[ngeb528]

Hi gang,

I've been reading tons of posts regarding casting and and saw several cautions about using black colorants and how it causes problems but most of the posts don't specify exactly what problems it causes.

Here's what I need info on:

1. Is there still a problem using black colorants?

2. What types work the best if I want to cast a black opaque blank?

3. Has anyone used embossing powder as a colorant for PR?

I just received a gallon of Silmar 41 and want to maximize my successes.

I really appreciate any info anyone is willing to share with me.

Thanks.

 

[ldb2000]

Hi Nancy . I have used black dye from Rit , it don't mix very easily , black powder coat powder , good black color but a real pain to mix , clumps city , the black dye made for resin (both kinds) good color but to get an opaque blank had to use allot , expensive . So far the best black pigment I have found is the black mica powder from coastal scents , mixes very well and is opaque with a very small amount , and it don't hurt the cure time of either type of resin .

 

[Glass Scratcher]

Nancy,

The problem, with many liquid/paste black and white PR casting pigments, is that they are made with compounds that absorb the cobalt promoters in the polyester resin, and they may also absorb the heat generated by the catalytic reaction and inhibit curing. This is true with Silmar 41 for both white and black polyester resin pigments. If you use enough black or white pigment to make a fully opaque casting, you will need to use the recommended 1% MEKp to catalyze the resin, or you may have to wait a day or 18 for the resin to cure. You can use the drops method if you must, but as some of us have discussed in previous threads, "how big are your drops?" It depends on the aperture that is in the dispenser bottle if it came with one, some don't and you have to cut your own. However, you can use a 1 or 3mL syringe with a 18g-21g needle on it(don't snip it, grind the tip down so you won't stick a hole in the side of your bottle) and draw the amount into the syringe and dispense it onto the surface of the resin, don't contaminate your catalyst syringe. You can use it many time for the day, but MEKp will cause polycarbonate syringes (1mL B-D Luer-Lok) to crack, and it will remove the markings used on the 3mL Polyethylene syringes.

Remember that you don't have to be exact to the nth degree for measurement but more accuracy increases repeatability. Remember to write down what you plan then make notes to what you actually did, and what the final outcome was.

1 metric ounce is 30mL
1% is .3mL

 

[td]

Embossing Powder

Nancy,

Embossing powder is not a "colorant". It will not dissolve in PR to become a smooth color. It stays in tiny dots. You can use it to "fill-ins" and inlays if you use CA with it. The heat from the CA (and maybe a little help from a heat lamp) makes it "plump". When I first started casting I didn't really understand what powdered pigment was and bought a big expensive colorful package of embossing powders thinking I was getting pigments. The worst part of this is there wasn't one person in the store (including the store manager) who could tell me if it was a pigment. They just kept telling me it was for making greeting cards and such, so it should work.:devil:

I, too, read everything I could find here (because this is the only place that had info) and did eventually find my way through the confusion. I found a life-long friend and casting buddy right here in Casting and Stabilization. I just wish he didn't live all the way over in FL. Charles (Glass Scratcher) really really knows his stuff.

You're doing the right things and asking the right questions. Keep on trucking and "With a Little Help From Our Friends" the adventure will never end!

 

[GouletPens]

I can't speak for Simlar 41, but for alumilite, I've used Mixol liquid dyes with good success. It's a VERY concentrated dye and I recently cast a black opaque blank using something like 4-6 drops per ounce, I don't quite remember. If you paint the inside of the blank with black Testors before gluing in the tube, that will really help to make sure the black blank looks black.

 

[DozerMite]

I cast a lot of black blanks and blanks with black in them using PR. I've never had a problem with cure or otherwise. I still get my blanks cured and on the lathe in an hour with black just as with any other color. That's my my experience using black and everyone's will differ.

 

[DurocShark]

1. No idea ...
2. PearlX Black is awesome.
3. I have used a few for specific purposes. They work more like a cast in material than a colorant. You will still need dyes or pigments.

 

[NewLondon88]

I cast a lot of black and I use the appropriate dyes. I also use embossing powders,
makeup powders, PearlEx, powdered pigments etc. I've found that the powdered
black (iron oxide) that I got from ArtStuf seems to color the resin, but also tends to
fall out of solution. Perhaps it is made for a swing resin, I'm not sure.
The liquid dyes work well but they're expensive. Fortunately, a little goes a long way.
If you were to cast just one blank, it would be very difficult to get the right amount
of dye on the end of a toothpick.. it tales so little dye that you always use too much
even when you think it isn't enough.

My favorites are the makeup powders if I'm not casting straight black. They aren't
a dye, but there's so much color fill in them that you wouldn't realize it isn't dye.
I haven't tried a straight black, so I don't know how that works.. but a black/red or
black/blue works very well and a little goes a long way.

Still, I'd get the liquid dyes that are made for PR. I got a set from Douglass & Sturgis
(ArtStuf) and the one ounce bottles were probably $3-$4 each. Keep in mind there are
both translucent and opaque dyes. Get both, as they work differently for coloring.
Opaque dyes won't become translucent if you use less, they'll just be thinner color.
IF you go with Alumilite, get the Alumilite dyes, too. I think those are all translucent
but you can make them opaque adding white, adjusting brightness with black.