---
title: "Sealed Parts: Water Resistance and Porosity | AMT PostPro"
description: "What “sealed” means for vapor smoothed parts: the surface, published porosity, exposure and burst-pressure results, and when to test your own."
canonical: https://amtechnologies.com/community/guides/sealing-and-water-resistance/
updated: 2026-10-06
type: guide
---
Community guide Tips & tricks / Post-smoothing

# What “sealed” means: water resistance and porosity

“Sealed” is the word you will see most often next to vapor smoothing. Here is what AMT has published about it.

- By AMT Team
- Guide
- 1 min read
- Updated Oct 2026
- Sources[1,2,3,4]

## The surface

A printed powder bed part has an open, porous skin. During smoothing the vapor condenses on that skin and evens it out. AMT’s vapor smoothing page says this enhances “the part’s strength, aesthetics, and water resistance”. The SFX and SF2X product pages show a TPU bellows (Forward AM TPU, MJF) with water on its surface, as printed and after smoothing. You can see the pair in [AMT gallery: before and after vapor smoothing](https://amtechnologies.com/community/guides/amt-before-and-after-gallery/).

## Published results

- **Porosity.** Protolabs reports reduced surface porosity on vapor smoothed flame-retardant parts, made in HP 3D HR PA 12 FR on HP MJF, with UL94 V-0 compliance (case study, Jun 2026).
- **Exposure.** Intelligent Energy’s hydrogen UAV casings, smoothed on a PostPro SF100, gained surface sealing, durability and resistance to environmental exposure (case study, Jan 2026).
- **Pressure.** On SLS PA2200, burst pressure rose by up to +7%[4] after smoothing (whitepaper, Jan 2024).

## If your part must hold water or pressure

A sealed surface is not the same as a pressure rating. If your part must hold fluid or pressure, test it under your own conditions, with the wall thickness and geometry you will use in production. A [benchmark](https://benchmarking.amtechnologies.com/submit?utm_source=amtechnologies.com&utm_medium=community-page&utm_campaign=site-2026&utm_content=sealing-and-water-resistance-guide) is a good place to start.

Forum · Over to you

Have you pressure-tested or leak-tested smoothed parts? Share the test, the material and the result.

[Answer in the forum thread (opens the community forum in a new tab)](https://amtpostpro.discourse.group/t/what-sealed-means-water-resistance-and-porosity/51)

Next step

## See the price. Run the numbers. Hold the part.

List prices are public and the cost-per-part math is yours to check, with no email needed for either. The free benchmark puts your own parts, vapor smoothed, in your hands.

1. 01 Quote

   ### Build your quote

   Pick a system and its options and get an itemized total on screen, from AMT’s published list prices.

   [Build your quote](https://amtechnologies.com/quote/)
2. 02 ROI

   ### Calculate your ROI

   Compare your cost per part with manual finishing, using your own labor rate and volumes. Every assumption is editable.

   [Calculate ROI](https://amtechnologies.com/roi/)
3. 03 Benchmark

   ### Test your parts, free

   Ship us your parts with a prepaid label. We vapor smooth them and send them back with before-and-after photos and a benchmark report.

   [Test your parts, free](https://benchmarking.amtechnologies.com/submit?utm_source=amtechnologies.com&utm_medium=community-page&utm_campaign=site-2026&utm_content=sealing-and-water-resistance-decision)

   No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks[5]

Prices: AMT list prices, excluding tax and shipping; confirmed in your formal quote.

[Not sure which system? Help me choose](https://amtechnologies.com/configurator/)

## Sources

1. [Vapor smoothing: SF and X-series family page and SFX, SF2X, SF50, SF100 product pages](https://amtechnologies.com/products/vapor-smoothing/) · AMT · read Oct 6, 2026 · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sfx-desktop-vapor-smoothing-system/) · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sf2x/) · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sf50/) · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sf100/)
2. [Flame-retardant 3D-printed parts with UL94 V-0 compliance (Protolabs case study)](https://amtechnologies.com/resources/case-studies/flame-retardant-3d-printed-parts/) · AMT · Jun 3, 2026
3. [Lightweight hydrogen UAV components enhanced through vapor smoothing (Intelligent Energy case study)](https://amtechnologies.com/resources/case-studies/3d-printed-uav-components/) · AMT · Jan 27, 2026
4. [Performance improvements of vapor smoothed SLS PA2200 parts (whitepaper)](https://amtechnologies.com/resources/whitepapers/performance-improvements-of-vapour-smoothed-sls-pa2200-parts/) · AMT · Jan 8, 2024
5. [PostPro benchmarking: send us your 3D printed parts](https://benchmarking.amtechnologies.com/) · AMT · read Oct 6, 2026