Hi, Ty, we use 3608-s with Brodak dope and Brodak retarder, no problems. In more humid times, we go to 3602-s, which has retarder already in it...again, works well with both Brodak and Sig dopes. As has been said, don't get carried away using the retarder. We've NOT had success with any other brand that is supposed to be "equal" to the DuPont thinners.