Crabapplehillstudio has this little blurb on their site:
" Crayon Tinting Instructions
Some of the patterns are tinted with Crayola Crayons. It's a really fun technique that looks SO COOL when it's done right!!! I like to start the process by coloring any area that's going to be tinted with white crayon. It sort of "fills" the weave of the fabric and smooths it out to create a base for the colored crayons. It also helps with the blending of colors......SO!!! You can go through quite a bit of white crayon in a single project. In "Calendula Patterdrip's Cottage" I used almost 3 white crayons. Having to buy another ENTIRE box of colored crayons just to get one, single, lousy white crayon is just, well... maddening! But...having a little box of all white on hand...is...happy-ing! Yes, that's a new word.
Color tinting is really easy...
Trace the design onto the fabric as usual
Make sure your work surface is clean and smooth and there isn't any lint/threads on the back of the fabric
Color all areas that you'll be tinting totally, but not heavily, with white crayon
Tint all areas as directed in the pattern (or use you own imagination!) I like to use a little circular motion
If you've made any mistakes in coloring, now is the time to fix them! After they're heat set it's too late!
One way to remove color is by dabbing with removable mounting putty such as Loctite Fun-Tak (the stuff you use to temporarily put posters on the wall)
Heat set with a hot iron by laying a white paper towel over the tinted area and pressing (you'll smell the wax). Remove the paper towel and look at it... if there's ANY color on it repeat the pressing process with a clean paper towel.
Crayon Tinted Fabric Washing Instructions
The crayon tinting embroidery method has existed since the 1930s or 40s and some things have survived, such as aprons and tea towels, with some fading. However, since this is an embroidered quilt and since we can't be absolutely sure about about new stain fighting soap formulas, the best thing to do is treat it like the very delicate hand-made quilt that it is, by using Woolite and washing with cold water on the delicate cycle or by hand washing. For example, if your child accidentally were to get crayon on their shirt, you'd probably never get it out, but Murphy's law being what it is, if it's going to come out of something, it will come out of the quilt. So be careful! "