Vapor Smoothing Nylon Prints: What It Changes
Vapor smoothing nylon prints closes surface pores and can lift elongation a lot, with a small drop in stiffness. What changes and what it can't fix.
Powder-bed nylon comes out matte and a bit chalky. That's fine on a bracket and wrong on something a customer holds. Vapor smoothing nylon is how most services fix it.
How Do You Get a Smooth Surface on MJF or SLS PA12?
Use a commercial vapor smoothing process. Acetone, the old trick for FDM prints, doesn't work on SLS or MJF nylon, so services use stronger solvents.
An r/3Dprinting user who buys MJF PA12 parts wanted to skip the 30%+ price bump for vapor smoothing from AMT or DyeMansion. They noted neither company lists ingredients on its SDS sheets. So they tried it at home. Acetone did nothing. IPA with Vertrel XF did nothing. A formic acid and dichloromethane dip, taken from a patent, gave only a weak effect.
What vapor smoothing nylon actually does
The Protolabs write-up walks through it. Parts hang on a rack in a warmed chamber, and the air is pulled out under vacuum. Solvent vapor condenses on the cooler parts and liquefies the surface just enough to close pores. Warm air, then hot air, drives the solvent off.
The numbers are for Protolabs' SLS PA11 Black. Roughness went from 250+ μin Ra to 64–100 μin Ra. XY elongation at break went from 30% to 120%, though the spread on that is ±80%. Tensile strength barely moved, and stiffness slipped from 1800 to 1700 MPa. That's one supplier and one material, so PA12 results may differ.
Protolabs is upfront about the limits. It won't fully match a molded surface or give a uniform finish on every shape, and it won't hide print defects.
Hanging points and fits
Parts have to hang during the process. A through hole lets them hang without marks. If there isn't one, Protolabs clips onto a wall or adds a temporary hook, and both can leave a mark or a small dimple.
Protolabs doesn't publish dimensional change, so on tight fits, measure a smoothed sample before you commit.
Where you start matters too. See why MJF comes out rougher than SLS and why dye wears off SLS parts. If you need color more than gloss, painting MJF parts is the other route.
Quoting a smoothed part
We print in MJF Nylon and SLS Nylon PA12, and the 3D printing capability page has the details. Want a smoothed finish? Ask us when you quote.
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