--- title: "Vapor Smoothing for HP MJF Parts | AMT PostPro" description: "How PostPro vapor smoothing seals and smooths HP Multi Jet Fusion parts in PA12, PA11, TPU and PP: results, workflow, case studies and systems." canonical: https://amtechnologies.com/learn/mjf-vapor-smoothing/ updated: 2026-10-07 type: learn --- Learn · HP Multi Jet Fusion # Vapor smoothing for HP Multi Jet Fusion parts. MJF vapor smoothing turns the gray, grainy, porous surface of an HP Multi Jet Fusion part into a smoother, sealed skin in one automated cycle. PostPro systems vapor smooth MJF parts in PA12, PA11, TPU and polypropylene, with the finishing agent chosen by material.[1] [Test your parts, free](https://benchmarking.amtechnologies.com/submit?utm_source=amtechnologies.com&utm_medium=learn-page&utm_campaign=site-2026&utm_content=mjf-mjf-hero) [Get a price](https://amtechnologies.com/configurator/) No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks[2] Printing process - **Surface roughness**: 13.42 → 1.18 µm[3] - BASF Ultrasint TPU01 · HP MJF - **Cytotoxicity**: No cytotoxic effects[4] - HP 3D HR PA 12 · PostPro Pure - **Materials**: PA12 · PA11 · TPU · PP[1] - MJF rows, AMT brochure Why MJF parts need finishing ## Strong parts, with a printed skin. MJF prints strong, accurate nylon and elastomer parts at volume. They come out of the build gray, slightly grainy and porous, which shows on any part that is touched, worn, washed or sold. 1. ### Porous surface Partly fused grains leave pores that take up water, sweat, dirt and dye unevenly. 2. ### Gray and grainy As-printed parts look printed. Vapor-smoothed MJF parts come out darker and more polished.[5] 3. ### Hygiene Medical, food and wearable parts need a surface that cleans. Sealed finishes keep out sweat and bacteria.[5] 4. ### Production volume MJF prints full builds of parts at a time; finishing has to keep up without a person per part. Published results ## What vapor smoothing measured on MJF parts. Each result names the material it was measured on. Results depend on material, printer and recipe. - Surface 13.42 → 1.18 µm[3] Surface roughness, as printed to vapor smoothed BASF Ultrasint TPU01 · HP MJF - Surface Reduced surface porosity on UL94 V-0 flame-retardant parts[6] Protolabs case study HP 3D HR PA 12 FR · HP MJF - Skin contact No cytotoxic effects and no loss of strength[4] Cytotoxicity test HP 3D HR PA 12 · HP MJF · PostPro Pure [MJF with PostPro Pure whitepaper](https://amtechnologies.com/resources/whitepapers/vapor-smoothing-of-hp-multi-jet-fusion-mjf-parts-with-amts-sustainable-postpro-pureconsumable/) [HP PA12 finishing whitepaper](https://amtechnologies.com/resources/whitepapers/automated-finishing-technology-for-post-processing-mjf-parts/) Workflow ## From build unit to finished part. Vapor smoothing slots in after cleaning and before dyeing or inspection. The vapor needs to reach the part’s real surface, so loose powder comes off first. 1. ### Print and cool The build cools in its unit before parts come out. 2. ### Clean off powder Loose, unfused powder is removed so the part’s surface is exposed. 3. ### Vapor smooth Parts hang on a rack in the PostPro chamber for one automated cycle: 1.5–2 h[7] on the SF50 and SF100. 4. ### Dye, inspect, ship Color if needed, check, and the part is ready for use. **MJF materials by finishing agent** | Material | PostPro Pure | FA326 | FA9202 | | --- | --- | --- | --- | | PA 12[1] | Listed | Listed | Not listed | | PA 12 Filled[1] | Listed | Listed | Not listed | | PA 11[1] | Listed | Listed | Not listed | | Forward AM TPU[1] | Listed | Listed | Not listed | | Lubrizol TPU[1] | Listed | Not listed | Not listed | | Polypropylene[1] | Not listed | Not listed | Listed | In production ## MJF parts in service. Published case studies on vapor-smoothed MJF parts, each linked to the full story. - GM Ultrasint TPU01 ### [Spoiler closeout seals](https://amtechnologies.com/resources/case-studies/basf-ultrasint-tpu01/) 60,000 parts, needed quickly to avoid delaying 30,000 vehicles[8] - Protolabs PA12 FR ### [Flame-retardant parts](https://amtechnologies.com/resources/case-studies/flame-retardant-3d-printed-parts/) Flame-retardant parts with improved surface quality and UL94 V-0 compliance[6] - Point Designs PostPro SFX ### [Partial hand prostheses](https://amtechnologies.com/resources/case-studies/3d-printed-partial-hand-prostheses/) Smooth, sealed surfaces that improve comfort and hygiene[9] Which PostPro ## Which PostPro for your MJF fleet. Desktop systems for R&D and small batches, production systems for full builds. Every PostPro system lists PA12, PA11 and TPU.[7] - Desktop SFX ### [PostPro SFX](https://amtechnologies.com/products/vapor-smoothing/postpro-sfx-desktop-vapor-smoothing-system/) Desktop vapor smoothing for R&D and low-volume production.[7] - Desktop SF2X ### [PostPro SF2X](https://amtechnologies.com/products/vapor-smoothing/postpro-sf2x/) Vapor smoothing with double the chamber capacity of the PostPro SFX.[7] - Production SF50 ### [PostPro SF50](https://amtechnologies.com/products/vapor-smoothing/postpro-sf50/) Delivers end-use parts for low-volume production.[7] - High volume SF100 ### [PostPro SF100](https://amtechnologies.com/products/vapor-smoothing/postpro-sf100/) Vapor smoothing sized for high-volume production.[7] [Help me choose](https://amtechnologies.com/configurator/) [See list prices](https://amtechnologies.com/pricing/) Questions ## MJF vapor smoothing: questions. Short answers from AMT’s published tests and material lists. Anything else, [ask an engineer](https://share.hsforms.com/1lOH82JpuRdSM-4wJ1ZeYlw45o6d?website_source=Vapor+Smoothing&utm_source=amtechnologies.com&utm_medium=learn-page&utm_campaign=site-2026&utm_content=mjf-talk). ### Can you vapor smooth MJF parts? Yes. PostPro systems vapor smooth HP Multi Jet Fusion parts in PA12, PA11, TPU and polypropylene, with the finishing agent chosen by material.[1] ### Does vapor smoothing work on HP 3D HR PA 12? Yes. In AMT’s test of HP 3D HR PA 12 printed by MJF and finished with PostPro Pure, the result was No cytotoxic effects and no loss of strength[4]. ### Do MJF parts need cleaning before vapor smoothing? Yes. Loose powder is removed first, so the vapor reaches the part’s real surface and finishes it evenly. ### Can vapor-smoothed MJF parts be dyed? Yes. Dyeing and vapor smoothing are often combined, and vapor smoothing alone already darkens an MJF part. Ask AMT which order suits your material. ### Which PostPro suits an MJF fleet? All four systems list PA12, PA11 and TPU. The SFX and SF2X suit R&D and small batches; the SF50 and SF100 take production volumes. The configurator helps you size it. 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=mjf-decision) No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks[2] 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. [PostPro benchmarking: send us your 3D printed parts](https://benchmarking.amtechnologies.com/) · AMT · read Oct 6, 2026 3. [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 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. [3D-printed orthoses enabled with vapor smoothing (Orthobroker case study)](https://amtechnologies.com/resources/case-studies/3d-printed-orthoses-with-vapor-smoothing/) · AMT · Oct 9, 2025 6. [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 7. [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/) 8. [GM's success: vapor smoothing for automotive production (spoiler closeout seal case study)](https://amtechnologies.com/resources/case-studies/basf-ultrasint-tpu01/) · AMT · Jan 23, 2023 · also [AMT](https://amtechnologies.com/industries/automotive/) · also [Forward AM](https://forward-am.com/gain-knowledge/blog/additive-manufacturing-gets-cars-into-showrooms/) 9. [Designing 3D-printed partial hand prostheses patients want to wear (Point Designs case study)](https://amtechnologies.com/resources/case-studies/3d-printed-partial-hand-prostheses/) · AMT · Jul 2, 2026