do dyes need urea mixed with them?

[redlumbb]

I have seen information on mixing dyes that tell you to add some urea to the mixture. Is this necessary/

[Noelle]

Urea (http://www.jacquardproducts.com/products/chemicals/urea.php) is a 'humectant', it attracts moisture from the air to help the fiber stay damp longer which gives more time for the reaction between the dye and soda ash (http://www.jacquardproducts.com/products/chemicals/sodaash.php) to occur. It is not critical for tie dye. I never use it and I am quite happy with my results, of course it might be interesting to do a test to compare one recipe with Urea and one without to see if I can tell a difference.
If you're just having fun with tie dye I wouldn't worry about it at all.:)

Noelle