Customers ask bureaus to paint SLS parts when dye can’t hit the color they need. On the Formlabs forum, a Fuse 1 user wanted Nylon 12 parts painted opaque white, “with no see through,” to match powder-coated metal plates in RAL 9003 Signal White.
Can you paint SLS parts to match a RAL color?
Yes. Formlabs’ SLS post-processing guide says painting may be better than dyeing when parts need bright colors or a match to a reference. In the forum thread, a Formlabs staff member said there was no official SLS painting guide. They had good results with acrylic paint and an airbrush, but said white usually needs several layers to get an even, opaque coat.
Why not just dye?
Dye only darkens or tints the base color. Formlabs recommends dyeing parts printed in its Nylon 12 White Powder, but standard Nylon 12 prints grey, so a light color like Signal White has to be painted or coated.
What does the process look like?
- Prep: depowder and media blast the parts first, so loose powder and Surface Armor don’t end up under the paint.
- Prime: Formlabs recommends a primer made for plastics, and says sprayed primer gives more consistent coverage. Its priming guide adds that a grey primer reveals surface flaws that you can sand or fill before painting.
- Paint: Formlabs says acrylic and enamel paints both work well on powder-printed parts. Spray painting gives the most even coverage and scales better, while brushing allows more detail.
- Build up thin coats: light coats keep fine details from filling in. Formlabs notes that a heat gun or hair dryer can speed drying.
Are there alternatives?
Formlabs also lists ceramic coating (Cerakote), powder coating and liquid polymer coatings for SLS parts. These cost more but are tougher. Choose based on how the part will be used, not just its color.
How should a bureau quote it?
Treat a color match as its own operation. Ask for the reference standard and gloss level, paint a sample to compare under the customer’s lighting, and price the extra coats that white and other light colors need over grey nylon.
Related on the Solvi blog: Should You Dye MJF Parts Black or Vapor Smooth Them?; SLS Nylon Yellowing: Why White Parts Turn Yellow; Depowdering SLS and MJF Parts: When Is Automation Worth It?.
Sources: Formlabs forum “Painting parts” thread; Formlabs guide to SLS post-processing; Formlabs: How to prime and paint 3D printed parts; Formlabs post-processing FAQs.