I was wondering if there was a certain volume of prints or quantity of prints after which the IPA bath used to clean excess resin off should be replaced. I am using clear resin, and have been getting inconsistent modulus tests on identical parts printed at the same time that have been post cured the same way. Could this be attributed to the IPA bath not being able to remove the resin as thoroughly as a fresh IPA bath, causing slight deformations on the surface of the print from extra resin being post cured?
I’m sorry to hear that you’re getting inconsistent results on your modulus testing. Can you share your testing methodology and if you are testing in compression or tension?
Ensure that you are giving your parts enough time to dry completely before post curing. Fresh IPA and dirty IPA may evaporate at different rates because as more material is dissolved, the vapor pressure of the solution will change. I’ve never tried post-curing parts that aren’t completely dry, but I don’t think that parts would be deformed from any residue left from an incomplete cleaning. My best guess is that different orientations of your model are more likely the source of the variation you’re seeing.
You may also try to improve your process by implementing a 2-stage wash for your modulus-sensitive parts. You could try using the finish kit buckets that came with your form 2 as a short “very dirty” first wash, or “very clean” second wash. Either way, be sure to check the cleanliness of your IPA using the included hydrometer and check out our post curing whitepaper.