Vapor Smoothing 3D Printed Parts

3D printing is an ideal choice for low-volume production, but surface finish has always been its shortcoming. Parts formed by SLS and MJF processes have a matte surface texture similar to sugar cubes; FDM technology leaves visible layer lines. Traditional post-processing methods like sanding, tumbling, or coating offer limited surface quality improvement. When appearance becomes a key consideration, engineers often turn to injection molding, CNC machining, or polyurethane casting.
The introduction of chemical vapor smoothing technology has completely changed this situation. This technology chemically treats 3D printed part surfaces via vaporized solvent, significantly improving surface quality and mechanical properties, making 3D printed parts truly suitable for low-volume end products. The process is compatible with most 3D printing polymers and elastomers, covering over 20 materials offered by KH-TAT.

KH-TAT uses AMT PostPro3D chemical vapor smoothing equipment. Unlike physical removal processes like sanding or bead blasting, Vapor Smoothing does not remove material but restructures the surface through chemical action.
During processing, parts are placed in a sealed chamber along with vapor smoothing agent (FA 326). The system automatically matches optimized processing parameters based on different materials and geometric features. The chamber measures 600 x 400 x 400 mm, ensuring vapor fully contacts part surfaces. After vapor deposition, a controlled chemical melting layer forms, filling surface irregularities through liquefaction and material redistribution, improving gloss and smoothness.
After processing is complete, the chamber is heated to discharge residual solvent into a collection tank, leaving no residue on part surfaces. Smoothed parts can be delivered directly or undergo subsequent processing like dyeing.

Through KH-TAT's instant quoting system, you can quickly obtain Vapor Smoothing pricing and lead times for Common Materials like HP MJF and SLS. This process uses batch processing mode, with per-unit costs decreasing as order volume increases, making it cost-effective. Standard lead times add 1-5 business days to the original printing time.
For specialty materials like SLS high-performance nylon blends, Nylon 11 EX, Nylon 12 AF, Nylon 12 HST, and Nylon 12 CF, Vapor Smoothing processing requires manual review. Please select "Other" when choosing Surface Finish Options and submit a quote request — our engineers will evaluate for you.

3D printed parts treated with chemical vapor smoothing show significantly improved appearance quality, with surface finish comparable to injection molding. Original SLS part surface roughness is typically above 250 μm Ra, which can be reduced to below 125 μm Ra after treatment, with some reaching 40 μm Ra — a surface improvement of up to 800% to 1000%. Note that this process forms a sealed smooth surface through material redistribution, but may still retain faint lines and structural traces.
Vapor Smoothing treatment is particularly suitable for industries with strict hygiene and appearance requirements like food processing, medical devices, and consumer goods. Studies show that treated Nylon 12 parts perform significantly better than untreated parts in terms of bacterial adhesion and growth, with multiple biocompatibility and safety test results meeting standards.

Additional advantages include:

• Uniformly sealed part surfaces with no additional coating
• Improved tensile strength, elongation at break, and flexural properties
• Surface is the substrate itself with no residual chemicals
• Significantly reduced hygroscopicity, improved dimensional stability
• Repeatable treatment results with closed-loop controllable process
• Non-visible areas can also be effectively treated
• Fine features and dimensional accuracy are preserved
• Improved appearance texture with more vibrant color expression

• Add radii to sharp internal corners to prevent rounded voids
• Keep wall and feature thicknesses above 0.040" (1 mm) to avoid distortion or defects
• Keep wall thicknesses uniform, similar to injection molding
• Be mindful that orientation-specific build lines may still be present, but smoothed
• Racking marks may be visible depending on how the work was held during processing
• Flexible materials, like TPU 88A, may have more surface imperfections versus rigid materials

Join industry experts for a webinar on making smooth, cost-effective, mechanically enhanced 3D prints with our vapor smoothing finish.Join industry experts for a webinar on making smooth, cost-effective, mechanically enhanced 3D prints with our vapor smoothing finish.

·Adding fillet transitions at sharp internal corners effectively prevents voids or defects from forming after treatment.
·Wall and component thickness is recommended to remain above 0.040 inches (1mm) to avoid deformation or surface imperfections.
·Maintaining uniform wall thickness, similar to injection molding design principles, helps improve Vapor Smoothing result consistency.
·Note that texture lines related to build orientation may still be faintly visible after smoothing treatment.
·Depending on how parts are fixtured during processing, clamping areas may show slight abrasion marks.
·Compared to rigid materials, flexible materials (like TPU 88A) may have more surface micro-defects after Vapor Smoothing treatment.