There is a difference between Retayne and Synthrapol. On the most basic level, Synthrapol suspends and removes excess dye (not all types of dye, but it also removes sizing, dirt, and oils) from cotton fibers and Retayne sets dye on fabrics. If fading will be a concern, and I think there is with batiks, I would use Retayne. Moonpi, bet you can't say "clothish" three times fast! :D