Filament Solvent Smoothing Chart: PLA, PETG, ASA, TPU and More
How Solvent Smoothing Works
Solvent smoothing works by briefly dissolving the outermost surface layer of a printed part. The polymer chains relax and flow, filling in layer lines and surface defects. When the solvent evaporates, the surface re-solidifies into a smooth, often glossy finish.
The key variable is chemical compatibility: a solvent must dissolve the specific polymer without attacking it too aggressively. Too little contact time and the surface barely changes. Too much and the part becomes gooey, loses detail, or warps entirely. The density and elongation properties of the base material matter too — PLA with a median tensile strength of 45 MPa (across 280 filaments) will behave differently under solvent exposure than TPU with its median elongation of 501% (across 64 filaments).
Master Solvent Smoothing Chart
The table below summarises which solvents work for each common filament type, the quality of the result, and the safety considerations involved.
| Filament | Best Solvent(s) | Result Quality | Method | Safety Level |
|---|---|---|---|---|
| ABS | Acetone | Excellent | Vapor or brush | Flammable — ventilate |
| ASA | Acetone | Excellent | Vapor or brush | Flammable — ventilate |
| PLA | Ethyl acetate, MEK, THF | Good (ethyl acetate) / Very good (MEK) | Brush or short vapor | Moderate — ventilate; MEK is higher hazard |
| HT-PLA | Ethyl acetate, MEK | Good | Brush | Moderate — ventilate |
| PETG | Dichloromethane (DCM), MEK (partial) | Moderate (MEK) / Good (DCM) | Light brush only | High hazard — DCM is a probable carcinogen |
| TPU | DMF, THF (limited) | Poor to moderate | Brush only | High hazard — DMF is toxic |
| HIPS | Limonene (d-Limonene) | Full dissolution (support removal) | Soak | Low — citrus-based, good ventilation recommended |
| PVB | Isopropyl alcohol (IPA) | Excellent | Vapor or brush | Flammable — ventilate |
| PVA | Water | Dissolves completely (support removal) | Soak | None |
| PC | Dichloromethane (DCM), acetone (light) | Good (DCM) | Brush | High hazard — DCM |
| PA (Nylon) | Formic acid (limited) | Poor — not recommended | N/A | Very high hazard — corrosive |
ABS and ASA: The Easiest Candidates
ABS and ASA are the most straightforward materials to smooth. Acetone dissolves both readily, producing glass-like results with minimal effort. The two polymers share a similar backbone chemistry — both are styrene-based — which is why they respond identically to acetone.
ABS from our database has a median tensile strength of 42 MPa (across 70 filaments) and a density of 1.06 g/cm³. ASA is slightly stiffer with a median tensile of 43.5 MPa (across 49 filaments) and density of 1.073 g/cm³. Importantly, ASA also carries better UV resistance than ABS, so vapor-smoothed ASA parts are better suited for outdoor use. If you are planning outdoor deployments, smoothed ASA is preferable to smoothed ABS.
Acetone Vapor Smoothing Process (ABS/ASA)
- Place a small amount of acetone in a sealed glass container — enough to cover the base, not to submerge the part.
- Suspend the part above the liquid on a wire or elevated platform.
- Seal the container. The acetone vapors will condense on the part's surface.
- Monitor every 5–10 minutes. Most ABS and ASA parts achieve a good finish in 15–30 minutes.
- Remove and allow to cure for at least 1 hour before handling.
Important: Acetone is highly flammable. Keep all heat sources, sparks, and flames away. Work in a ventilated area and use a glass container, never plastic (acetone dissolves many plastics).
PLA: Works, But Requires More Caution
PLA can be smoothed with ethyl acetate or MEK (methyl ethyl ketone). Ethyl acetate is found in nail polish remover and is far safer and more widely available. MEK produces faster and more consistent results but is a stronger solvent with higher health and fire hazards.
PLA's median tensile strength is 45 MPa across 280 filaments in our database, with median elongation of 8%. After solvent smoothing, surface hardness and dimensional accuracy are slightly reduced — a consideration for functional parts. For decorative prints, the trade-off is generally worth it.
Vapor smoothing PLA with ethyl acetate is possible but requires careful control of exposure time. PLA is more sensitive than ABS to prolonged solvent contact and can lose structural integrity if over-exposed. Brush application gives more control: apply a thin coat with a soft brush, allow to cure 5–10 minutes, then repeat if needed.
HT-PLA
HT-PLA (heat-treated PLA) filaments such as those marketed as "annealed PLA" retain similar solvent behaviour to standard PLA. In the Filabase database, HT-PLA materials (23 total) have a median tensile strength of around 56 MPa — higher than standard PLA — but their response to ethyl acetate and MEK is comparable because the base polymer chemistry is unchanged. The key difference is that HT-PLA parts should be smoothed before annealing if possible, as the annealing process improves heat resistance and may reduce surface flow during smoothing.
PETG: Mostly Resistant
PETG is notorious for being difficult to smooth. Its chemical resistance is largely a feature — PETG's median tensile strength of 48 MPa (across 110 filaments) and good layer adhesion make it a reliable engineering material — but this same resistance means common solvents barely touch it.
Dichloromethane (DCM, also called methylene chloride) will smooth PETG, but DCM is classified as a probable human carcinogen by IARC and is restricted or banned in consumer products in many jurisdictions. For most hobbyists, PETG smoothing is not worth the chemical hazard.
MEK will have a slight effect on PETG — it can reduce the sharpness of layer lines with careful brush application — but results are inconsistent and far inferior to acetone on ABS. If a smooth surface is your priority, consider printing in ABS or ASA instead of PETG.
TPU: Solvent Smoothing Not Recommended
TPU is an elastomer, and its flexibility comes from its chemical structure — one that makes it largely resistant to the solvents available to most makers. The median elongation at break for TPU in our database is 501% across 64 filaments, far exceeding rigid thermoplastics. This elastomeric network resists surface flow under typical solvent exposure.
DMF (dimethylformamide) and THF (tetrahydrofuran) will attack TPU surfaces, but both are high-hazard solvents. DMF is a reproductive toxin. Neither is suitable for hobbyist use without proper laboratory safety equipment.
For flexible parts where surface finish matters, consider mechanical finishing (sanding with fine-grit paper, 400–800 grit) or design choices like using larger layer heights to reduce visible layer lines.
PVB: The Easiest "Premium" Smoothing Experience
Polyvinyl butyral (PVB) is a specialty filament designed specifically for solvent smoothing. It responds to isopropyl alcohol (IPA) — one of the safest and most accessible solvents available. The smoothing result is exceptional: PVB prints can achieve near-injection-moulded surface quality.
Prusament PVB (Prusament PVB) has a tensile strength of 50 MPa and elongation at break of 4.6%. Polymaker's PolySmooth (Polymaker PolySmooth) has a tensile of 44.1 MPa and elongation of 3.4%. Both are slightly less stiff than standard PETG but produce outstanding surface quality.
IPA vapor smoothing for PVB follows a similar process to acetone for ABS, but with a lower hazard profile. IPA is still flammable and should be treated with respect, but it does not carry the carcinogenicity concerns of DCM or the reproductive toxicity of DMF.
HIPS: Built for Dissolution
High Impact Polystyrene (HIPS) is primarily used as a soluble support material alongside ABS. It dissolves cleanly in d-Limonene, a citrus-derived solvent. HIPS from our database (9 filaments with tensile data) has a median tensile strength of 25 MPa and density of 1.05 g/cm³ — weaker than ABS, which is why it is used as a support rather than a structural material.
d-Limonene requires extended soaking (several hours to overnight) rather than vapour exposure. It is significantly safer than most smoothing solvents — though proper ventilation is still advisable. For ABS structures with complex internal geometry, HIPS supports + d-Limonene dissolution is one of the most practical dual-material workflows available.
Note: d-Limonene will also slightly attack ABS surfaces with extended contact. Keep soak times to what is necessary and rinse parts in IPA after dissolution to stop any continued action.
PVA: Water Dissolution
PVA (polyvinyl alcohol) dissolves in warm water — no special solvents required. Like HIPS, PVA is primarily a support material rather than a structural filament. The four PVB materials in the database with tensile data show values ranging from 22 to 78 MPa depending on formulation. PVA is hygroscopic and degrades quickly when exposed to ambient humidity, so storage in a dry box is essential.
Solvent Properties Comparison
| Solvent | Primary Use | Flash Point | Key Hazard | Availability |
|---|---|---|---|---|
| Acetone | ABS, ASA | −20°C | Highly flammable | Hardware stores, pharmacies |
| Ethyl acetate | PLA | −4°C | Flammable, mild irritant | Nail polish remover, hardware stores |
| MEK | PLA, PETG (light) | −9°C | Flammable, CNS irritant | Hardware / industrial stores |
| Isopropyl alcohol (IPA) | PVB | 12°C | Flammable | Pharmacies, hardware stores |
| d-Limonene | HIPS dissolution | 48°C | Low — skin sensitiser with prolonged use | Online, some hardware stores |
| DCM (methylene chloride) | PETG, PC | None (non-flammable) | Probable carcinogen, toxic vapours | Restricted in many countries |
| Water | PVA | N/A | None | Everywhere |
Safety: The Non-Negotiables
No smooth surface finish is worth a serious health hazard. Before starting any solvent smoothing, follow these rules:
- Ventilation first. All flammable solvents should be used outdoors or in a well-ventilated space. Even "low hazard" solvents like d-Limonene can accumulate in enclosed spaces.
- No open flames or sparks. Acetone, ethyl acetate, MEK, and IPA are all highly flammable. A single spark from a motor or switch can ignite vapour.
- Use glass or metal containers. Acetone and MEK dissolve many common plastics. Use glass jars with metal lids for storage and working containers.
- Nitrile gloves. Solvent-resistant nitrile gloves protect skin. Standard latex offers poor protection against organic solvents.
- Avoid DCM and DMF. Dichloromethane and dimethylformamide are high-hazard industrial chemicals. If you do not have access to a proper fume hood and PPE, avoid them entirely.
- Store safely. Keep solvents in their original containers, away from heat sources and direct sunlight, in a dedicated, locked storage area.
Matching Filament Choice to Finishing Method
If a smooth surface finish is a key requirement for your project, the filament choice and the finishing method should be decided together, not separately. Here is a decision framework:
| Use Case | Recommended Filament | Smoothing Method | Notes |
|---|---|---|---|
| Decorative display model | PLA or ABS | Ethyl acetate (PLA) or acetone (ABS) | PLA is easier to print; ABS gives better finish |
| Outdoor decorative part | ASA | Acetone vapor | ASA resists UV degradation; ABS yellows outdoors |
| Medical / skin contact model | PVB | IPA vapor | Smooth surface reduces bacteria trapping; verify biocompatibility with specific brand |
| Functional engineering part | PETG or ASA | Mechanical sanding, not solvent | PETG chemical resistance is valuable; avoid DCM |
| Support material removal | HIPS (with ABS) or PVA (with most) | d-Limonene soak (HIPS) or water soak (PVA) | HIPS requires dual-extrusion printer; PVA is safer |
| Flexible part with smooth surface | TPU | Mechanical sanding only | No safe solvent option for hobbyist use |
Frequently Asked Questions
Can I use acetone on PLA?
No. Acetone does not dissolve standard PLA. PLA requires ethyl acetate or MEK. Attempting acetone on PLA will produce no meaningful result on most formulations.
Does solvent smoothing weaken parts?
Yes, to a measurable degree. The solvent dissolves and redistributes surface polymer chains, which can reduce hardness and dimensional accuracy. For decorative parts the reduction is negligible. For load-bearing parts, mechanical finishing (sanding) is preferable because it removes material rather than disrupting the polymer structure.
Is there a solvent that works on everything?
No. Each polymer family has a different chemical structure and requires a compatible solvent. This is why PETG's chemical resistance — the property that makes it resistant to acetone and ethyl acetate — is also what makes it difficult to smooth.
Can I smooth carbon-fibre filled filaments?
With caution. CF-filled ABS will respond to acetone, but the carbon fibres are insoluble and may become more prominent at the surface after smoothing. The result can look uneven. CF-filled PLA behaves similarly with ethyl acetate. For CF variants where surface finish matters, sanding is generally more predictable.
Is IPA safe for PLA or ABS?
IPA has little to no effect on PLA or ABS. It is used to clean prints (removing release agents and finger oils) and to smooth PVB, but it will not smooth PLA or ABS surfaces.