Post-Processing

Quick answerStart at 120–180 grit for FDM parts to level layer lines, work through 240, 320, 400. For resin, start at 400–600 grit. Wet sand above 400 grit for smoother results. Do not skip grits — moving from 180 directly to 400 leaves 180-grit scratches that show through primer.

Quick answerApply 2–3 thin coats of filler primer, letting each coat dry fully before applying the next. Lightly sand between coats with 400–600 grit. Primer fills surface texture and creates a chemically compatible base for topcoat adhesion. Never apply topcoat directly to bare plastic.

Quick answerRemove FDM supports while the part is still warm from the build plate — they release much more easily. For resin, remove supports after washing but before full UV curing, when the material is still slightly flexible. Use flush cutters, not pliers.

Quick answerFor most parts: sand progressively (120→240→400), apply filler primer, wet sand at 600+, then paint. For a faster finish on non-critical parts, use a thick filler primer like Rust-Oleum 2-in-1 and sand once. For the best results, use automotive body filler (Bondo/spot putty) on deep layer lines before priming.

Quick answerAcetone vapor smooths ABS and ASA. MEK works on ABS, ASA, and some PETG formulations. Ethyl acetate works on PLA but results are less predictable. Dedicated machines like the Polymaker Polysher (for PolySmooth PVB) and the AMT PostPro automate the process for production use.