Pastel Chalks for Colouring Plaster?

[Guest]

Hi

I have just bought a cobble mould from Diorama Debris & wondered if you can use pastel chalk powdered down to colour plaster before mixing or do I need to use a proper pigment powder?

Thanks

Steve

[Guest]

plaster can be coloured with quite a few things that are water based or disolve in water.

oil pastels/paints will tend to seperate in the mix but could give a reasonable effect. (if you add a touch of washing up liquid to the mix then the oil based pigments will be held better as the mix will be more of an emulsion)

Normal chalk (or chalk based pastels) will be held in suspension if you mix it well enough and should have an effect on the overall colour.

Water-colours or acrylic paints will give the overall mix a solid colour, this could be enhanced with some appropriate chalks and powders.

These "proper" pigment powders are handy, but you can improvise your own quite easily.

[Guest]

Thanks Colin very much appreciated.

Never thought of using watercolours or acrylics. Seems obvious now you've said. I think i will go this route & weather with the chalk pastels after.

Steve

[Guest]

I have just found a really good way to colour the plaster. I found 5litres of black liquid cement dye in the shed. Mixing this with water at different ratios you can vary the colour from black to light grey. My biggest concern was the dye would stain the silicon mould but no such problem. Now my cobbles have that granite look that I was after.

[Guest]

When making a plaster mix for bases i use the cheap stuff from DIY stores.

I mix it with water, PVA glue and to pre colour it i use the small tester pots from the paint aisle in the DIY store of choice.

They are cheap and are available in loads of useful colours.

I tend to go for the darker colours as the plaster mix has a tendency to lighten the colour.

Hope this helps some one.

Malc.