I agree with Dudemeister: For small / medium quantity output the Form Wash is not ideal:
Try to wash a printed part in the “dirty bucket”, then put a bit of IPA in a plastic cup and put that cup in an ultrasonic cleaner. The IPA will turn black/blue/ whatever after seconds. No reason why it should be any different with form wash.
For most applications that residual resin is not a problem (probably way less then +0,1mm in part dimensions after curing). The bigger issue imho is the usage of different resins: If you wash a white part in a bucket that was used for black you will find black sparkles all over the part. When using Castable you do not want to have a “residue coating” from other resins since it will reduce the surface quality / surface roughness of the casted part.
I am very curious to hear first-hand experience from people using form wash with different resins.
We should remember that Form Wash was probably designed for high output users who can afford to buy several units and/or to dump 20€ worth of IPA in shorter intervals. I understand that for printing services or in a high volume production (Form Cell) it is much cheaper to keep the production streamlined then having an employee constantly handling IPA buckets.
On another subjects: Is Form Cure beeing shipped already? Any experience?