According to one of the links below, you only need to use the "fabric" crayons on synthetic or synthetic blends. Both say for cotton fabric and use paper towels. Maybe use parchment paper over and under the paper towels to prevent wax &/or color from getting on your ironing surface and iron.
https://phoebemoon.com/tutorials/crayon-quilts.htm
https://www.thepatternco.com/crayon-quilts/
Janey - Neat people never make the exciting discoveries I do.
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