Chemical Post-Processing of 3D Prints: How to Achieve a Smooth Surface

ABS and ASA — Acetone (The Gold Standard)

The combination of ABS or ASA with acetone is the most widespread and reliable method of chemical smoothing for home use. Acetone is cheap, readily available at any hardware store, and the results are excellent — the surface gains a smooth, glossy appearance with minimal effort.

How to do it:

The most common method is acetone vapor smoothing. The printed part is placed inside a sealed container (ideally glass), with a small amount of acetone poured at the bottom or soaked into paper towels lining the walls. The container is sealed and the vapors gradually dissolve the outer layer of the plastic. The entire process typically takes 15–60 minutes depending on the size of the part and ambient temperature.

Important guidelines:

• Acetone is flammable and its vapors are explosive — work in a well-ventilated area, away from open flames.
• Overexposure can blur fine details and deform thin walls.
• After removal, let the part dry for at least 30 minutes, ideally in a well-ventilated space.
• ASA responds to acetone just as well as ABS, so this method covers both materials.

HIPS — Acetone and Limonene

HIPS (High Impact Polystyrene) is interesting because it responds to two different solvents. Acetone smoothing with HIPS is even faster than with ABS — layers dissolve almost instantly and the part dries significantly quicker.

The second solvent is d-limonene — a natural, biodegradable substance derived from citrus peels. In 3D printing, limonene is primarily used to dissolve HIPS support structures, but it can also be used for surface smoothing. The part is submerged in limonene and the support material gradually dissolves over 12–24 hours.

PLA — A Trickier Case

Standard PLA is highly resistant to common solvents. Acetone does not work on PLA — it can actually damage the material, making it “gummy” without achieving any real smoothing.

There are two chemical approaches for PLA, both with significant limitations:

Ethyl acetate

Ethyl acetate vapors can smooth the PLA surface. The procedure is similar to acetone smoothing with ABS: the part is placed in a sealed container with ethyl acetate applied to paper towels. However, the process is considerably slower — taking hours instead of minutes, and the results are less consistent.

Dichloromethane (DCM)

More effective than ethyl acetate, but it is a hazardous chemical that is toxic when inhaled and regulated in many countries. It is definitely not recommended for home use.

PETG — Ethyl Acetate (With Caution)

PETG can be surface-treated with ethyl acetate vapors, but it is an advanced technique requiring caution. The process is similar to acetone smoothing: the part is suspended inside a sealed glass container lined with paper towels soaked in ethyl acetate. The part must not touch the towels.

Smoothing time ranges from a few minutes to several hours — depending on vapor concentration and temperature. Results are less predictable than with ABS + acetone, so we recommend experimenting on a test piece first.

PVB (PolySmooth) — Isopropyl Alcohol (The Easiest Method)

PVB filament, known primarily under the brand name PolySmooth by Polymaker, was specifically developed for easy chemical smoothing. The solvent is ordinary isopropyl alcohol (IPA), which is safe, inexpensive, and available at any pharmacy.

Two approaches:

Important notes about PVB:

• PVB is more moisture-sensitive than PLA — it requires dry storage (filament dryer or airtight container with desiccant).
• Smoothing works best on organic, rounded shapes. Flat surfaces and sharp edges smooth less effectively, and the infill pattern may become visible through them.
• Print parameters are very similar to PLA (nozzle temperature 210–230 °C), making the transition easy.

Nylon (PA) and Other Engineering Materials

Chemically resistant materials such as nylon (polyamide), polypropylene (PP), or TPU/TPE do not respond to acetone or common solvents. There is no practically usable method for chemical smoothing of these materials at home.

Professional solutions do exist — for example, industrial vapor smoothing systems from AMT (PostPro), which use special proprietary solvents compatible with nylons produced via SLS and MJF technologies. However, these solutions are far beyond the budget and space of a typical home user.

For nylon and other resistant materials, the best alternatives remain mechanical methods: sanding, filler, primer, and clear coat.

Quick Reference Table

Safety Guidelines

Conclusion

Chemical smoothing is a powerful tool, but not a universal one. The best combination for home use remains ABS/ASA + acetone, thanks to its simplicity, cost, and result quality. If you prefer PLA-like printing with the option for easy smoothing, consider PVB filament with isopropyl alcohol. And for materials like nylon or TPU, it pays to invest time in quality sanding and coating.

The key to success is always patience, choosing the right solvent for the specific material, and following safety guidelines.

Sources

1. Prusa Research — “Improve your 3D prints with chemical smoothing” — blog.prusa3d.com
2. Prusa Knowledge Base — “HIPS” — help.prusa3d.com
3. Xometry — “How to Smooth 3D Prints: PLA, ABS, and FDM Prints” — www.xometry.com
4. FormFutura — “3D Print Post-Processing: Techniques for a Flawless Finish” — www.formfutura.com
5. COEX 3D — “The Best Methods for PETG Filament Smoothing” — coex3d.com
6. Polymaker — “PolySmooth” — us.polymaker.com
7. AMT PostPro — “How to Smooth 3D Prints – Your Ultimate Guide” — amtechnologies.com
8. 3D Printed — “Chemical Smoothing 3D Prints: 12 Expert Techniques” — www.3d-printed.org
9. Airwolf 3D — “Dissolving HIPS with Limonene” — airwolf3d.com