there is no difference in using water based ink or solvent based ink, for the heat transfer printing of polyester. but the problem is that there are a big chance that the pigments will get into your print heads and they may be clog up due to this. as far as i remember, many of my customer buy usa made pigment so it is not much problem if we use them. but if you want to use china type pigments, you can dissolve them with water and then put this solution in an airbrush machine to spray when printing on polyester fabric