Yes, but you only need to do this with the first wash after you transfer.
Make sure the item is inside out and that you use cold or warm water only,
not hot. Low heat drying or line drying is preferred. It does "set" the
colors, but the transfer will tend to wrinkle a little or even crack
slightly over time. Depends on your transfer paper. I have had bad luck with
several of the common store brands. I buy my t-shirt transfer paper from the
monthly computer fair, where Asian dealers have bulk high-quality stuff. Use
a silicon sheet to iron over the transfer once it is on the shirt and you
will add months of life to the design. Hope that helps. Cheers, DJKathyA
Pessimists are Usually Right, but Optimists are Happier!