Advice on dyeing plaster!

[Stevem]

I am going to make some plaster waste molds and I need to buy some dye for the first coat of plaster. Is there any special dye needed for plaster? I have paint pigments I can add for the coloring. One of them is a glycol based pigment and the other is a water-born based pigment. Will either of these suffice or is one better than the other? With the glycol based pigment I'm told it has soap mixed with it, I was thinking this might be a benefit as a built in release agent. Anyone done this? I want to use a first layer of colored plaster as a signal of sorts to denote when I'm getting close to the actual cast upon demolding.

Thanks in advance for your help,

[GlennT]

Don't know if this helps, but I have had success with dyeing not the mold, but the plaster positive, using ink dyes found at a store that caters to people who do "scrapbooking" . ( I put that in quotes because it is a phenomena that I don't quite get, but is apparently a big thing with a strata of society that were at a loss for what to do with their time after their pet rocks died!)

The dyes come in a huge range of colors in very tiny plastic bottles at a moderately high price. But they are nice to work with and do a great job of staining your fingers. ( So exercise some care unless you are bored with flesh tones )

[Stevem]

That is funny! Thanks for the input Glen.

[Landseer]

Use so called limeproof colors such as Quikcrete liquid concrete colors sold in home improvement stores, Menards, Amazon.com, ACE hardware etc.
It comes in dark brown, charcoal black, terra cotta red and a light brown.

Limeproof colors are also available in powder form at other places that sell tints and pigments but many of those are very expensive, especially in certain colors.

If you use more than about 4 tablespoons to 5-6 qts of water when mixing hydrocal for example, it WILL affect the setting time- slowing it down considerably and one spoonfull either way makes the tipping point between normal set time and drastically longer.
You shouldn't need more than a teaspoon or tablespoon to a bucket of water if all you want is a TINT.

Using paint colors or other pigments can affect set, strength and other problems such as bleeding out on the surface and getting it on your hands every time you handle the mold. I used some dry red pigment once and the hydrocal NEVER hardened and stayed like slush.

[PTsideshow]

You have to use the same chemical make up I guess you would call it 20 years ago cranking out faux wood Christmas pins and ornaments out of plaster. I wanted it to look like a wood colored base. A call to the US Gypsum. pre computer days. Was informed that it had to be an alkaline type dye not an acidic base type paint. The cement powder coloring is the cheapest. And the colors vary in prices due to the chemicals in it. Greens and blues being the most expensive. As they are copper based.
With a lot of paint and other dyes. You have problems as previous post stated doesn't set up, or if it does it can range from crumbly to egg shell glass brittle, and if you add any paint ect to the outer layer it can be splotchy to suck it in for days LOL. Look for a larger building supplier that deals with cementfinishers/brickies for a wider selection. It is also sold by the 1/2 or pound. and they can generally tell you how much to start with.

[Merlion]

I am going to make some plaster waste molds and I need to buy some dye for the first coat of plaster. Is there any special dye needed for plaster? I have paint pigments I can add for the coloring. ...
I have seen it tried. As they are waste molds to be broken up and thrown away after use, wouldn't any color pigment that add color to the plaster do?

[PTsideshow]

When all else can't be found you can always try using food coloring in the water it may give you enough tint and not cause problems to notice with the setting or strength of the plaster. :D

[Stevem]

Thanks everyone for all the suggestions. I actually found some powdered paint from one of the school supply houses and I think this is going to work great. Looks to be the stuff I used when in school.

[dondougan]

Hi Steve,

Haven't made any waste molds for years, but always used laundry bluing from the grocery store mixed-into the plaster for the first coat.

Don

www.dondougan.com

[racine]

watch out for powdered paint, it can spread to the object mould,and make the 'waste skin' unstable- you can dye more than u wish. adding colour to a waste mould is a generally good idea, keep it very light and yes the builder stuff is class. it also depends on the separator u r using, make a test, save a lot it could.

[Stevem]

Thanks Don and Racine for your insight. Don we ought to meet at the coffee shop up on the square one morning.

[Tlouis]

You might want to try Rit clothing dye sold at some supermarkets. And it's cheap.