Keeping clear resin clear (and smooth)

I know that I’m not the only one with this goal, so I’ll describe my latest efforts.

I love how clear looks as it comes out of the printer so I designed a part (my mold for a square o-ring) that could be placed directly in the cure chamber w/o washing it with IPA. I designed it with a central ring that would hold it so that the groove for the o-ring would be upside down while printing and curing (no supports where they would be a problem). It came out of the printer looking great. I removed it from the build platform and carefully placed it on my silicone pad, cut to fit the cure platform. on the supporting ring, set it for a long cure time, per my previous experience with unwashed cure times. It cured fine, but due to the viscosity of the resin my precisely sized groove had’globs of resin in it making the mold useless. Back to the drawing board (an antique device that some of you may never have seen) :slight_smile:

I printed it again, this time with a 10 minute wash. Cloudy AGAIN! I give up, I’m going to try gloss Krylon this time.

Print at 25 microns.
Wash it carefully with IPA- get all the residue out. post cure per Formlabs recommendations.

If you are going to cast the O ring in Tin Cured silicone- then use two thin coats of Clear Gloss ACRYLIC to make the printed resin optically clear.

3D printing is really not a good tool for making things that are very clear, unless the part can stand up to polishing then you have to work out another solution. I’ve only had success on parts that I can sand easily to get them smooth.