Finishing · Gloss & Seal

Vapor Smoothing for 3D Printed Parts

The finish that makes a printed part look moulded. A controlled solvent vapor reflows the surface to a smooth, glossy, sealed skin — closing porosity, improving impact resistance, and reaching internal features no tool could. On powder-bed nylons, TPU, TPE and PP, plus ABS and ASA on FDM — finished in-house in the UK, from prototype to production batch.

Quote vapor smoothing → All finishing

Vapor smoothing · chemical smoothing · glossy sealed finish · injection-moulded look · layer line removal

Overview

A sealed, glossy surface — not just a smoother one

Vapor smoothing is the process that makes a printed part look moulded. A precisely controlled solvent vapor surrounds the part and gently reflows the outermost layer of material, so the microscopic peaks and valleys left by printing fuse together into a smooth, glossy skin. The layer lines do not get abraded away — they get melted flat.

The important part is what happens beneath the shine. Reflowing the surface seals it, closing the fine porosity that printed parts carry. That makes the part more resistant to moisture, chemicals and dirt, improves its impact resistance, and can make it liquid-tight — benefits that matter as much on a functional part as the gloss does on a cosmetic one.

Because it is a vapor rather than a tool, it reaches everywhere the vapor can flow — including internal channels and complex geometry that no line-of-sight process could finish.

Small precision RYSE 3D printed parts with a smooth vapor smoothed sealed surface

How it works

The process, step by step

Prepare & load

Parts are cleaned and loaded into the sealed smoothing chamber so the vapor can reach every surface.

Controlled vapor exposure

A precisely controlled solvent vapor surrounds the parts and softens the outermost layer of material in a controlled, even melt.

Surface reflow

The microscopic peaks and valleys from printing flow together, fusing into a smooth, glossy, sealed skin across the whole part.

Set & finish

The process is stopped and the parts stabilise, leaving a consistent injection-moulded-like finish, inside features and out.

Why it matters

What vapor smoothing gives you

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An injection-moulded look

A glossy, smooth surface that closely resembles a moulded part — the finish for cosmetic and customer-facing components.

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A sealed surface

Reflowing closes the fine surface porosity, so parts resist moisture, chemicals and dirt and are easier to clean — useful for hygiene-critical parts.

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Better impact resistance

Sealing the surface removes the micro-notches that cracks start from, so smoothed parts take an impact better than as-printed ones.

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Reaches internal features

Vapor flows where tools cannot, so internal channels and complex geometry finish evenly — a line-of-sight process cannot do this.

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Can be liquid-tight

A sealed, non-porous surface supports liquid- and air-tight applications that a porous printed wall would not.

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Consistent across a batch

A controlled, repeatable process gives the same professional finish part to part across complex geometries.

Applications

What vapor smoothing is used for

Where a sealed, smooth surface earns its place — a mix of function and finish across very different parts.

Flexible SLS 3D printed automotive bellows boot vapor smoothed by RYSE 3D

Automotive components like this flexible SLS printed bellows boot benefit from vapor smoothing.

SLS 3D printed eyewear frame vapor smoothed by RYSE 3D for a comfortable finish

Eyewear frames can be more comfortable for the wearer when vapor smoothed.

SLS 3D printed orthotic insole vapor smoothed by RYSE 3D

SLS printed orthotic insoles can be vapor smoothed for added comfort and aesthetic benefits.

Compatibility

Which materials can be vapor smoothed

Vapor smoothing is chemistry, so it only works where the solvent can reflow the polymer — which is why what we can smooth depends on the process the part is printed with. These are the materials we vapor smooth on each, and the chamber size for each. Get material and size right up front and the rest is straightforward.

Reviewed by the RYSE 3D engineering team · August 2026

Process	Materials we vapor smooth	Max part size
SLS	PA11, PA12, TPU, PP*	250 × 390 × 250 mm
MJF	PA11, PA12, TPU, TPE, PP* and others	400 × 600 × 400 mm
FDM	ABS, ASA	400 × 600 × 400 mm

*PP on request — confirmed per project. Not sure whether your material and size suit smoothing? Tell us at quote and we’ll confirm before you commit.

Quote parts, vapor smoothed → All finishing processes

Honest limits

When vapor smoothing is not the answer

The material is not compatible

It works on our powder-bed nylons and TPU (SLS and MJF), TPE and PP on MJF, and ABS and ASA on FDM — but not on every grade. Polycarbonate (PC-FR) and carbon-filled grades will not reflow, so if a glossy sealed finish is essential, choose the material with that in mind and talk to us first.

Critical fine detail

Because the surface reflows, very sharp edges and the finest detail soften slightly. Where crisp detail is essential, tell us, or consider an A-class painted SLA part instead.

Tight tolerances

Reflowing the surface can shift a critical dimension by a small amount. Flag tolerance-critical features before smoothing and we will plan and inspect around them.

A matte or satin finish

Vapor smoothing produces gloss. For an even satin surface with dimensions untouched, vibro polishing is the process.

The smoothest SLS for dyeing

For powder-bed parts headed for dye, shot blast polishing is our standard preparation and often the better route.

Oversized parts

Smoothing runs in a chamber, so parts above the sizes in the table cannot go through whole. We can sometimes split, smooth and rejoin — tell us the part size at quote.

FAQ

Vapor smoothing FAQ

What is vapor smoothing?

Vapor smoothing is a chemical finishing process that gives 3D printed parts a smooth, glossy, sealed surface. A controlled solvent vapor reflows the outermost layer of material so the microscopic ridges from printing fuse together, producing a finish close to injection moulding. As well as the gloss, it seals the surface, reducing porosity and improving resistance to moisture, chemicals and impact.

What is the difference between vapor smoothing and vibro polishing?

Vapor smoothing is chemical and vibro polishing is mechanical, and they give different finishes. Vapor smoothing reflows the surface to a glossy, sealed, moulded-look finish and reduces porosity. Vibro polishing tumbles parts with media for an even satin surface while preserving dimensions, without sealing them. Choose vapor smoothing for gloss and a sealed surface; choose vibro polishing for a consistent satin finish with dimensions untouched.

Which materials can be vapor smoothed?

It depends on the process. On SLS we smooth PA11, PA12, TPU and PP; on MJF, PA11, PA12, TPU, TPE, PP and others; on FDM, ABS and ASA. It is a chemical process, so grades the solvent will not reflow — such as polycarbonate (PC-FR) and carbon-filled grades — are not compatible. Tell us your material at quote and we will confirm.

Does vapor smoothing make parts stronger or waterproof?

It can improve both durability and sealing. Reflowing the surface closes the fine porosity that printed parts carry, which improves resistance to moisture, chemicals and dirt, raises impact resistance by removing surface micro-notches, and can make a part liquid- or air-tight. The exact result depends on the part and material, so tell us what it needs to do.

Can vapor smoothing reach internal channels?

Yes — this is one of its advantages over mechanical finishing. Because it is a vapor rather than a tool or media, it flows into internal passages and complex geometry and finishes them evenly, where a line-of-sight process such as blasting or hand polishing cannot reach.

How big a part can you vapor smooth?

It depends on the process the part was printed with, because smoothing runs in a chamber with a defined envelope. For MJF and FDM parts the maximum size is 400 x 600 x 400 mm; for SLS parts it is 250 x 390 x 250 mm. Larger parts can sometimes be split, smoothed and rejoined — tell us the part size at quote and we will confirm.

Does vapor smoothing change part dimensions?

It can shift a critical dimension by a small amount, because the surface layer reflows. For most cosmetic and functional parts this is not an issue, but where a fit is tolerance-critical we ask you to flag those features before smoothing so we can plan and inspect around them.

What finish does vapor smoothing produce?

A smooth, glossy surface that closely resembles an injection-moulded part, with the surface sealed rather than just polished. It is a gloss finish — for a satin surface use vibro polishing, and for a defect-free show surface use A-class paint.

How much does vapor smoothing cost?

It is quoted with the part, since cost depends on the material, part size and quantity. Add it to an instant quote, or contact us for parts printed elsewhere — and tell us the material so we can confirm it is compatible.

Ready when you are

Printed parts that look moulded — and are sealed.

Vapor smoothing on nylon, TPU, TPE, PP, ABS and ASA, in-house in the UK — a glossy, sealed finish that reaches inside the part as well as out.

Get an instant quote → All finishing processes

Printed, finished and inspected at our own ISO 9001 facility in Shipston-on-Stour, Warwickshire. Call us on 024 7736 0144.