If they are CHALK pastels, you can grate them through a fine grater/tea strainer and then use a soft artists brush to color fondant or gum paste pieces. If they are OIL pastels, they are not for use on cakes.
Rae
Glad to be helpful, Barbara.
If you find that a color is too bright and you want to tone it down, you can either grate white into it, or better yet (to conserve your white pastel stick) just add a bit of cornstarch to it. Try to keep brushes dedicated to the same/similar colors and to clean them, again pounce them in more cornstarch onto a paper towel, rather than wetting them.
Rae
Hey, Barbara -
I looked for these chalks online, but could not find a link for them. Are they labeled non-toxic? If not, they cannot be used on a cake.
If you have a link for them, please post it for us.
Thanks --
Theresa 
The chalks are labelled non-toxic. They were purchased from a cake decorating shop in Melbourne, Australia and they ship items worldwide.
Any queries can be sent to them : [email protected].
Apparently these are also used in scrapbooking and they are available on www.scrapbookfantasies.com.au.
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