A surface finish adds cost in three ways: labour per part, a batch or minimum charge that is shared across the order, and extra lead time. As-made surfaces cost nothing extra. Bead blasting and dyeing usually add little per part in a full batch; vapour smoothing adds more; painting, which is mostly skilled hand work, often adds the most. Anodising and powder coating apply to metal parts and are usually priced by the batch.
Key points
- Leave a surface as made unless someone sees it, touches it, or needs it to seal.
- Finishes add labour per part, a batch or minimum charge, and days to the lead time.
- Batch finishes are cheap per part in a full batch and expensive in a small one.
- Some finishes change dimensions: smoothing rounds edges, coatings add thickness.
- Choose the process with the finish in mind; the right process can make a finish unnecessary.
Why finishing is priced separately
Every manufacturing process leaves its own surface. FDM leaves layer lines and support marks. Resin leaves a smooth surface with small marks where supports were cut away. SLS and MJF leave a matte, slightly grainy nylon surface. Machining leaves tool marks; sheet metal leaves cut edges.
Changing that surface is post-processing: separate work, often on separate equipment, sometimes at a separate company. It does not depend much on how long the part took to make. It depends on surface area, how easy the surface is to reach, how many parts share a batch and who does the work. That is why a good quote shows finishing as its own line, as the 3D printing cost calculation guide does.
The finishes compared
| Finish | Applies to | What it does | How it is usually priced |
|---|---|---|---|
| As printed or as machined | Everything | The process’s own surface after basic cleaning | Included |
| Sanded and smoothed | FDM, resin, some SLS | Removes layer lines and support marks by hand | Labour per part, by area and access |
| Bead blasted | SLS, MJF, resin, metals | Even matte surface from a blasted media | Short labour per part; cheap in batches |
| Dyed | SLS and MJF nylon | Colours the surface layer, usually black | Bath per batch plus handling |
| Vapour smoothed | SLS and MJF nylon, TPU; ABS in FDM | Reflows the skin to a sealed, smoother surface | Machine cycle per batch plus handling |
| Primed and painted | Most plastics, metals | Any colour, gloss level or texture | Mostly labour per part, several coats |
| Anodised | Aluminium, titanium | Hard oxide layer, optionally coloured | Batch or minimum lot, plus masking |
| Powder coated | Steel, aluminium | Thick, durable coloured coating | Batch or minimum lot, plus masking |
Finishes for printed parts
As printed. The cheapest finish and often the right one. Lower layer height reduces visible layer lines at the price of print time, which is sometimes cheaper than sanding them away.
Sanding and smoothing. Removing layer lines and support marks by hand is pure labour. It scales with surface area and with how hard the surfaces are to reach: an open flat face is quick, a part with pockets and ribs is slow. Primer and filler between sanding passes improve the result and add more time.
Bead blasting. Fine media blasted at the part gives an even matte texture and removes loose powder. On SLS and MJF a basic blast is part of cleaning every part; a finer cosmetic blast is a short extra step.
Dyeing. SLS and MJF nylon takes dye well. Parts are immersed in a hot dye bath, usually black, in batches. MJF parts come out of the machine grey, so dyeing them black is very common. The colour penetrates a little way into the surface, so a light scratch shows less than paint would. The MJF vs SLS guide compares the surfaces each process starts from.
Vapour smoothing. A solvent vapour softens the outer skin of the part, which flows and seals. Nylon parts come out smoother, semi-gloss and easier to clean. It runs in a chamber in batches, so it carries a cycle cost shared across the batch. It can soften sharp edges and fine text, so check small details.
Painting. Any colour, gloss level or texture, including matched brand colours. It is mostly skilled hand work: preparation, primer, sanding, coats and masking. That makes it one of the most expensive options per part.
Finishes for metal parts
Bead blasting on machined or printed metal hides tool marks and gives a uniform matte look. It is often the first step before anodising or coating, and it removes sharp burrs, though it is not a replacement for deburring edges properly.
Anodising grows a hard oxide layer on aluminium (and some other metals). It can be dyed in many colours, and a hard-coat variant gives a thicker, wear-resistant layer. The coating grows partly outward, so tight bores and threads need allowance or masking. Anodising usually runs in batches at a specialist line with a minimum lot charge.
Powder coating sprays a charged powder onto the part and cures it in an oven into a thick, durable coat. It suits steel and aluminium parts that face weather or handling. It needs masking on threads, holes and contact faces, and because it is baked, it does not suit plastics.
Both change the measured surface roughness and the dimensions of the part. Specify which faces must stay uncoated.
Worked example: what finishing adds to a batch
Worked example: 20 small SLS nylon parts. Every figure is an example for the arithmetic, not a market price.
As-printed price, including basic depowdering: €12.00 per part. Finishing labour: €45/h. Dye bath: €30 per batch. Smoothing chamber: €120 per cycle. Paint and primer: €2.00 per part. Each finish below starts with a cosmetic bead blast.
| Finish | Calculation | Added per part | Price per part |
|---|---|---|---|
| As printed | none | €0.00 | €12.00 |
| Bead blasted | 3 min × €45/h | €2.25 | €14.25 |
| Dyed black | €2.25 + €30 ÷ 20 + 2 min × €45/h = €2.25 + €1.50 + €1.50 | €5.25 | €17.25 |
| Vapour smoothed | €2.25 + €120 ÷ 20 + 3 min × €45/h = €2.25 + €6.00 + €2.25 | €10.50 | €22.50 |
| Primed and painted | €2.25 + 25 min × €45/h + €2.00 = €2.25 + €18.75 + €2.00 | €23.00 | €35.00 |
Now order 5 parts instead of 20. The dye bath share becomes €30 ÷ 5 = €6.00 instead of €1.50, and the smoothing share €120 ÷ 5 = €24.00 instead of €6.00. Batch finishes are cheap only in a full batch.
The batch effect is the same arithmetic as a minimum order value: a fixed cost has to be covered whatever the quantity. It is why many shops set a minimum charge per finish.
Lead time
Finishing adds days, not just euros. A batch finish may wait until enough parts arrive to fill the bath or chamber; an outside anodiser or powder coater has its own queue and shipping both ways. A quote that adds finishing should add lead time with it, or the delivery date is wrong.
How to choose
- Decide which surfaces matter: seen, touched, sealing, sliding or none.
- Pick the cheapest process that gets close to that surface as made. The design for 3D printing guide covers orientation, which decides where layer lines and support marks fall.
- Add the lightest finish that closes the gap.
- Mark faces and features that must not be coated or smoothed.
In Quotometry, a shop sets each finish up as an option with its own per-part charge, minimum charge and added lead days, and the quoted price and lead time follow the finish the buyer picks. The 3D printing cost calculator is a quick way to see how finishing compares with the rest of a printed part’s price.
Questions people ask
What is the cheapest surface finish?
The as-made finish: as printed, or as machined. It costs nothing beyond the standard cleaning every part gets, such as support removal or depowdering. Every other finish adds labour, a machine cycle, a batch charge or an outside supplier. If the surface is not seen or touched and does not seal anything, leave it as made.
What is vapour smoothing?
Vapour smoothing exposes a printed part to a solvent vapour that softens and reflows its outer skin. On SLS and MJF nylon it seals the surface and gives a smoother, semi-gloss finish that is easier to clean. On ABS printed in FDM, acetone vapour is a similar idea. It can change sharp edges and small features slightly, so check fine details.
Can you anodise a 3D printed part?
Anodising works on aluminium and some other metals, such as titanium, so it applies to machined aluminium and to some metal printed parts, not to plastic prints. Anodising grows an oxide layer partly into and partly out of the surface, so tight-tolerance features and threads need allowance or masking. Ask the finisher what thickness to expect.
Why does a finish cost so much on a small order?
Many finishes run in batches: a dye bath, a smoothing chamber, an anodising line, a powder coating oven. The batch costs about the same whether it holds one part or fifty, and outside finishers often charge a minimum lot. On a small order that fixed cost is shared by few parts, so each one carries a large share of it.
Quotometry prices every part from your own machines and rates, on your website, in seconds.