---
title: "Vapor Smoothing and Post-Processing Glossary | AMT PostPro"
description: "Plain definitions of vapor smoothing, vapor polishing, vapor honing, Ra roughness, sealing, MJF, SLS, SAF, HSS, finishing agents and other finishing terms."
canonical: https://amtechnologies.com/learn/glossary/
updated: 2026-10-07
type: learn
---
Learn · Glossary

# Vapor smoothing and post-processing glossary.

Plain definitions of the terms used around vapor smoothing and the finishing of 3D printed and machined plastic parts: the process, the printers, the materials, the measurements. Where a term has a PostPro specific, it is stated with its source.

- **ABS Acrylonitrile butadiene styrene**: An opaque, tough engineering thermoplastic used for housings, enclosures, fixtures and prototypes. It is printed by extrusion (FDM) and machined from sheet and rod. PostPro vapor smooths FDM-printed ABS with FA326 on the SF50 and SF100,[1] and vapor polishes machined ABS on the PostPro SF100 with PostPro Pure[2].
- **Acetone smoothing Hobby method**: Exposing extrusion-printed ABS parts to acetone vapor in a jar or a heated box. It smooths the surface, but time, temperature and vapor concentration are not controlled and the solvent escapes into the room, so results vary from part to part. Industrial vapor smoothing runs the same idea as a controlled, closed machine process.

- **Closed loop Equipment**: A vapor smoothing machine that keeps its finishing agent inside the system and recovers it after the cycle, instead of venting or discarding it. The PostPro SF50 and SF100: Closed-loop system with consumable recovery[3].
- **Conditioning Cycle stage 01**: The first stage of a PostPro cycle. Parts are conditioned in the chamber to reach the right processing conditions.[3]
- **Consumable See finishing agent**: In vapor smoothing, the liquid finishing agent the machine vaporizes, plus wear items such as filters. See finishing agent.
- **Curing Cycle stage 03**: The third stage of a PostPro cycle. The consumable is removed from the surface and the surface resolidifies.[3]
- **Cytotoxicity Testing**: Whether a material damages living cells, tested in a lab on cell cultures. It matters for parts worn against the skin. In AMT’s published test on HP 3D HR PA 12 · HP MJF · PostPro Pure: No cytotoxic effects and no loss of strength[4].

- **Dimensional change Measurement**: How much a part’s measured dimensions differ after a process, usually given as a percentage. Vapor smoothing reflows a thin surface skin, so the change is small: ≤ 0.4%[5] on PA12 · voxeljet HSS parts in AMT’s published test.
- **Drying Cycle stage 04**: The last stage of a PostPro cycle. Parts are dried so no consumable remains in the chamber, ready for use.[3]
- **Dyeing Finishing method**: Coloring parts in a heated dye bath. Dyeing changes color, not surface texture, and it is often combined with vapor smoothing. [Compare finishing methods](https://amtechnologies.com/learn/vapor-smoothing-vs-other-finishing-methods/).

- **Elongation at break Measurement**: How far a test bar stretches before it breaks, as a percentage of its starting length. A rough, notched surface makes parts break early; a smooth one lets them stretch further. In AMT’s published test on PA12 · voxeljet HSS: +38.1% (XY)[5].

- **FA326 PostPro finishing agent**: The PostPro agent with the longest material list: 100+ thermoplastics[6], on the SF50 and SF100[6].
- **FA9202 PostPro finishing agent**: Dedicated consumable for finishing polypropylene parts[1]. AMT lists it for the SFX, SF50, SF100[6]. [Polypropylene vapor smoothing](https://amtechnologies.com/materials/polypropylene/).
- **FDM Fused deposition modeling**: Extrusion 3D printing: a heated nozzle lays down a thermoplastic filament line by line, leaving visible layer ridges. PostPro covers industrial FDM materials such as ULTEM and Onyx. [Vapor smoothing industrial FDM parts](https://amtechnologies.com/learn/fdm-vapor-smoothing/).
- **Finishing agent Consumable**: The liquid a vapor smoothing machine turns into vapor to smooth the part. PostPro uses three: PostPro Pure, FA326 and FA9202, each for a set of materials and machines.[6] [PostPro consumables](https://amtechnologies.com/products/vapor-smoothing/consumables/).
- **Flame polishing Finishing method**: Passing a torch flame over the edge of a plastic part, usually acrylic, so the surface melts and turns glossy. It works edge by edge, needs a skilled hand, and can bubble or stress the part; it cannot reach internal features. Compare vapor polishing.
- **Food-contact validation Testing**: Lab testing that shows a finished material releases substances below the limits a food-contact regulation sets. For PostPro, one combination has been tested: FABULOUS DETECT PA11 · PostPro Pure, with Extractables well within regulatory limits under US FDA 21 CFR §177.1500[7].

- **HMI Human-machine interface**: The screen an operator uses to run a machine. The PostPro SF50 and SF100 have an HD touchscreen[1]; the SFX a 7-inch touchscreen[1].
- **HSS High Speed Sintering**: A powder-bed 3D printing process in which an inkjet head prints an absorbing ink and an infrared lamp fuses the inked powder. AMT has published vapor smoothing results on HSS PA12. [Vapor smoothing SAF and HSS parts](https://amtechnologies.com/learn/saf-hss-vapor-smoothing/).

- **Media finishing Finishing method**: Driving abrasive beads or grit at a part with compressed air to clean it and even out its surface. It leaves a uniform matte finish but does not seal it, and it reaches what the media can hit, no more. It is often the step before vapor smoothing or dyeing.
- **MES/ERP connectivity Equipment**: A link between a machine and the factory’s manufacturing execution or planning software, so jobs and results are tracked. On the PostPro SF50 and SF100: MES/ERP connectivity[1].
- **MJF HP Multi Jet Fusion**: HP’s powder-bed 3D printing process: agents are jetted onto a layer of powder and fused with infrared energy. MJF parts in PA12, PA11, TPU and polypropylene are vapor smoothed on PostPro systems.[1] [Vapor smoothing MJF parts](https://amtechnologies.com/learn/mjf-vapor-smoothing/).

- **PA11 Polyamide 11, nylon**: A nylon made from castor oil, tougher and more flexible than PA12. Printed by MJF · SLS · SAF · HSS[6]. [PA11 vapor smoothing](https://amtechnologies.com/materials/pa11/).
- **PA12 Polyamide 12, nylon**: A widely used powder-bed 3D printing nylon, strong and dimensionally stable. Printed by MJF · SLS · SAF · HSS[6]. [PA12 vapor smoothing](https://amtechnologies.com/materials/pa12/).
- **PEI (ULTEM™) Polyetherimide**: A high-heat, flame-resistant engineering plastic, printed by FDM and machined from stock. PostPro Pure handles FDM ULTEM parts and machined PEI.[6] [Vapor polishing machined PEI](https://amtechnologies.com/applications/vapor-polishing-machined-plastics/#pei).
- **Polycarbonate (PC) Thermoplastic**: A tough, clear plastic used for guards, covers and lenses. Machined PC turns frosted where the cutter passed; vapor polishing brings back the clarity. [Vapor polishing polycarbonate](https://amtechnologies.com/applications/vapor-polishing-machined-plastics/#polycarbonate).
- **Polypropylene (PP) Polyolefin**: A light, chemically resistant plastic printed by MJF and SLS. Its resistance to solvents means it needs a dedicated finishing agent, FA9202. [Polypropylene vapor smoothing](https://amtechnologies.com/materials/polypropylene/).
- **Porosity Surface**: The open pores in a powder-bed printed surface, where powder grains did not fully fuse. Pores take up water, dirt and dye. Vapor smoothing reflows the surface and closes them: Reduced surface porosity on UL94 V-0 flame-retardant parts[8] (HP 3D HR PA 12 FR · HP MJF).
- **PostPro Brand**: AMT’s brand of automated post-processing systems for 3D printed parts. The vapor smoothing range is the [SFX](https://amtechnologies.com/products/vapor-smoothing/postpro-sfx-desktop-vapor-smoothing-system/), [SF2X](https://amtechnologies.com/products/vapor-smoothing/postpro-sf2x/), [SF50](https://amtechnologies.com/products/vapor-smoothing/postpro-sf50/) and [SF100](https://amtechnologies.com/products/vapor-smoothing/postpro-sf100/).
- **PostPro Pure FA5802[6]**: The finishing agent that runs in every PostPro vapor smoothing system (SFX, SF2X, SF50, SF100[1,6,9]). Readily biodegradable (OECD 301 B)[10,11]. Hazard labels: Warning · H315 causes skin irritation · H319 causes serious eye irritation[11].
- **Powder-bed fusion 3D printing family**: 3D printing processes that fuse a thin layer of polymer powder at a time: MJF, SLS, SAF and HSS. Their parts come out with a grainy, porous surface, which is what vapor smoothing was built to finish.
- **Powder removal Preparation**: Cleaning loose, unfused powder off powder-bed parts after printing. Parts are cleaned before vapor smoothing, so the vapor reaches the part’s real surface.

- **Ra Arithmetic mean roughness**: The most quoted surface-roughness figure: the average distance of the measured surface profile from its mean line, in micrometers. Lower is smoother. Studies also use other parameters, so always check which one a figure uses.
- **RFID Equipment**: Radio-frequency identification. PostPro SF systems use it for RFID consumable recognition and management[3] and for RFID-controlled access[1].

- **SAF Selective Absorption Fusion**: Stratasys’ powder-bed 3D printing process, in which an absorbing fluid and infrared energy fuse PA12 or PA11 powder. AMT has published process insights on vapor smoothing SAF parts with PostPro Pure.[12]
- **Sealing Surface**: Closing the pores of a printed surface so water, sweat and dirt cannot get in. Vapor smoothing seals a part with its own reflowed material; a coating seals it with an added layer.
- **SLS Selective laser sintering**: A powder-bed 3D printing process in which a laser fuses polymer powder, usually PA12 or PA11, layer by layer. [Vapor smoothing SLS parts](https://amtechnologies.com/learn/sls-vapor-smoothing/).
- **Surface roughness Measurement**: A measure of the fine texture of a surface, taken with a stylus or optical profilometer and given in micrometers. In AMT’s published test on BASF Ultrasint TPU01 · HP MJF parts: 13.42 → 1.18 µm[13], as printed to vapor smoothed. See Ra.

- **TPE Thermoplastic elastomer**: The family of rubber-like plastics that can be melted and reshaped. Printed by MJF · SLS · SAF · FDM[6]. [TPU and TPE vapor smoothing](https://amtechnologies.com/materials/tpu/).
- **TPU Thermoplastic polyurethane**: A flexible, hard-wearing elastomer used for seals, lattices, footwear and grips. Printed by MJF · SLS · SAF · HSS[6]. [TPU vapor smoothing](https://amtechnologies.com/materials/tpu/).
- **Tumbling Finishing method**: Rotating or vibrating parts in a bowl of abrasive media for hours to round edges and smooth surfaces. It suits robust parts, rounds fine detail and leaves the surface open.

- **UL94 V-0 Flammability rating**: The strictest of the vertical-burn V ratings in the UL94 plastics flammability standard: a test bar must stop burning quickly and not drip flaming particles. Protolabs vapor smooths flame-retardant PA12 parts that carry it.[8]

- **Vapor honing Not a vapor process**: A wet abrasive finish, also called liquid honing: a slurry of water and fine media is driven at the part by compressed air. Despite the name, no solvent vapor is involved, and it does not reflow or seal plastic. Not to be confused with vapor polishing or vapor smoothing.
- **Vapor polishing Also vapour polishing**: Reflowing the surface of a machined plastic part with a controlled solvent vapor to remove tool marks and bring back clarity, usually on polycarbonate and acrylic. AMT does it on the PostPro SF100 with PostPro Pure[2]. [Vapor polishing machined plastics](https://amtechnologies.com/applications/vapor-polishing-machined-plastics/).
- **Vapor smoothing Also vapour smoothing**: A chemical finishing process for 3D printed polymer parts: a controlled solvent vapor softens the outer skin, the surface reflows and seals, and the bulk of the part keeps its shape. PostPro systems run it in four stages: Conditioning · processing · curing · drying[3]. [What is vapor smoothing?](https://amtechnologies.com/learn/what-is-vapor-smoothing/)

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=learn-page&utm_campaign=site-2026&utm_content=glossary-decision)

   No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks[14]

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. [AMT PostPro brochure: automated post-processing systems for additive manufacturing, V4.0 (June 2026)](https://info.amtechnologies.com/download-document?document_name=brochure) · AMT · Jun 2026
2. [AMT company statement: SF100 + PostPro Pure vapor polishing of machined plastics (PC, PMMA, ABS, PSU, PEI, PA)](https://amtechnologies.com/applications/vapor-polishing-machined-plastics/) · AMT · Oct 6, 2026
3. [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/)
4. [Vapor smoothing of HP MJF parts with sustainable PostPro Pure consumable (whitepaper)](https://amtechnologies.com/resources/whitepapers/vapor-smoothing-of-hp-multi-jet-fusion-mjf-parts-with-amts-sustainable-postpro-pureconsumable/) · AMT · Jun 20, 2025
5. [Vapor smoothing voxeljet's HSS PA12 with AMT PostPro (whitepaper)](https://amtechnologies.com/resources/whitepapers/vapor-smoothing-voxeljets-hss-pa12-with-amt-postpro/) · AMT · Feb 6, 2024
6. [Vapor smoothing consumables: PostPro Pure (FA5802), FA326 and FA9202](https://amtechnologies.com/products/vapor-smoothing/consumables/) · AMT · read Oct 6, 2026
7. [Fabulous and AMT validate food contact compliance for 3D-printed parts using DETECT PA11 and PostPro Pure](https://amtechnologies.com/news/fabulous-and-amt-validate-3dprinted-food-contact-compliance/) · AMT · Apr 7, 2026
8. [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
9. [PostPro SF2X product page](https://amtechnologies.com/products/vapor-smoothing/postpro-sf2x/) · AMT · read Oct 6, 2026
10. [Health & Safety Certification Overview, solvent: PostPro Pure (FA5802)](https://6983077.fs1.hubspotusercontent-na1.net/hubfs/6983077/Website/Specification%20Sheets/AMT_HEALTH_SAFETY_PURE_CERTIFICATION_EN.pdf) · AMT · Apr 2024
11. [PostPro Pure Safety Data Sheet, V1.0](https://6983077.fs1.hubspotusercontent-na1.net/hubfs/6983077/Website/MSDS/PostPro_PURE_MSDS.pdf?ver=2) · AMT · Jan 16, 2023
12. [Vapor smoothing for Stratasys SAF: process insights (whitepaper)](https://amtechnologies.com/resources/whitepapers/vapor-smoothing-stratasys-saf/) · AMT · Mar 19, 2025
13. [Ultrasint TPU01 enhancement with PostPro vapor smoothing (whitepaper)](https://amtechnologies.com/resources/whitepapers/surface-enhancement-of-ultrasint-tpu01-parts-by-postpro-vapor-smoothing/) · AMT · Nov 7, 2022
14. [PostPro benchmarking: send us your 3D printed parts](https://benchmarking.amtechnologies.com/) · AMT · read Oct 6, 2026