---
title: "Vapor Smoothing for 3D Prints | Injection-Molded Finish | OpenSpindle"
description: "Chemical vapor smoothing seals and smooths FDM and SLS/MJF nylon prints to a glossy, injection-molded-like, watertight finish without eroding fine features."
canonical: https://openspindle.com/capabilities/vapor-smoothing
---

# Vapor smoothing for 3D printed parts

A controlled solvent vapor melts the outer surface of a print just enough to flow smooth, leaving a glossy, sealed, injection-molded-like finish that is also easier to clean and often watertight. Upload your model and we'll source competitive quotes from qualified manufacturing partners.

## How to design for Vapor Smoothing

Vapor smoothing melts and flows a thin outer skin of the part, so it is a finishing step to plan for, not a coating added on top.

| Design rule | Typical spec | Why |
| --- | --- | --- |
| Compatible materials | ABS, ASA, and PA11/PA12 nylon | The solvent vapor has to chemically soften the plastic; PLA and most photopolymer resins are not good candidates. |
| Surface roughness improvement | roughly Ra 8-12 microns as-printed down to Ra 1-2 microns smoothed | The vapor flows the outermost layer, closing layer lines into a continuous glossy surface. |
| Dimensional impact | typically under 0.01 mm change | Material flows rather than being added, so most tolerances hold; call out critical fits so the shop can confirm. |
| Fine detail and sharp edges | not ideal below about 0.5 mm feature size | Sharp edges soften slightly and embossed text or fine lettering can blur or fill in. |
| Watertightness | often fully sealed against liquids and gases | The melted skin closes the micro-porosity inherent to FDM and powder-bed prints, useful for fluid- and air-handling parts. |

Typical values vary by material, wall thickness, and shop process; confirm feasibility for your specific part.

## Vapor smoothing vs other finishing methods

When a mechanical or manual finish fits better than a chemical vapor process.

| Process | Best for | Typical volume | Choose it over Vapor Smoothing when |
| --- | --- | --- | --- |
| Media tumbling | Bulk edge-break and light smoothing | Any batch size | You want a lower-cost mechanical process for deburring and light smoothing and can accept a matte, non-glossy result that can round off fine detail. |
| Bead blasting | Uniform matte finish | Any batch size | You want a consistent matte, low-sheen surface and do not need the part sealed or made glossy. |
| Hand sanding and priming | Spot cosmetic finishing | Low volume or one-off | You need cosmetic work on a small number of parts and can absorb manual labor instead of a batch chemical process. |

## Industries Served

- Consumer products
- Medical devices
- Robotics
- Automotive
- Fluid and air handling

Vapor smoothing is common wherever a printed part needs to look and feel like an injection-molded product, or hold liquid or gas.

## Frequently Asked Questions

### What is vapor smoothing?

Vapor smoothing exposes a 3D printed part to a controlled solvent vapor that briefly softens and flows the outer surface. As the solvent evaporates, the surface re-solidifies smooth and glossy, closing layer lines and sealing surface porosity without removing significant material.

### Which materials can be vapor smoothed?

ABS and ASA from FDM printing, and PA11/PA12 nylon from SLS or MJF, are the common candidates because their chemistry responds to the solvent vapor. PLA and most SLA/DLP resins do not vapor smooth well and usually need a different finishing method.

### Does vapor smoothing change part dimensions?

The change is typically under 0.01 mm since the process flows the existing surface rather than adding a coating layer. Fine features and sharp edges can soften slightly, so call out critical tolerances and detail when you request a quote.

### Does vapor smoothing make parts watertight?

Often, yes. FDM and powder-bed prints have inherent micro-porosity between layers or fused powder grains, and the melted, flowed surface from vapor smoothing typically seals that porosity, which is why it is a common step for fluid- and air-handling parts.

### Vapor smoothing vs tumbling or bead blasting?

Tumbling and bead blasting are mechanical processes that deburr and produce a matte finish but do not seal porosity or add gloss. Vapor smoothing is a chemical process that produces a glossy, sealed, injection-molded-like surface, though it works on a narrower set of materials.

### Is vapor smoothing good for parts with fine text or embossed logos?

Not usually. The vapor flows plastic across the surface, which can blur fine embossed text or soften sharp-edge-critical features. For parts where crisp fine detail matters more than a glossy sealed finish, a lighter mechanical finish is often a better fit.

## Other Capabilities

- [3D Printing (overview)](https://openspindle.com/capabilities/3d-printing.md)
- [FDM / FFF 3D Printing](https://openspindle.com/capabilities/fdm-3d-printing.md)
- [SLS 3D Printing](https://openspindle.com/capabilities/sls-3d-printing.md)
- [MJF 3D Printing](https://openspindle.com/capabilities/mjf-3d-printing.md)

## Get vapor smoothing quotes

Upload your prints and we'll source quotes from qualified manufacturing partners offering vapor smoothing for a glossy, sealed, injection-molded-like finish.