The moment a part comes off the printer is rarely the moment it is finished. 3D printing post-processing — sanding, smoothing, painting, dyeing, and sealing — is the stage that turns a raw print into something you can hand to a client, test against mating parts, or sell as a finished product. After more than two decades of fabrication work in Los Angeles, we can tell you the finishing plan often matters as much as the printer itself. Here is how each post-processing option works, which technologies need it, and when it is worth the added cost.
Why Post-Processing Matters for 3D Printed Parts
Every 3D printing technology leaves its own signature on a part. FDM prints show visible layer lines. SLA resin parts come off the build platform coated in uncured resin and need washing and UV curing before they are safe to handle. SLS and MJF nylon parts emerge with a matte, slightly grainy surface and loose powder in every crevice. Metal DMLS parts carry support structures and a rough as-built texture. For a quick fit-check prototype, none of that may matter. For presentation models, end-use products, film props, and parts that must slide or seal against other components, post-processing closes the gap between printed and finished.
The Most Common 3D Printing Finishing Techniques
Support removal and sanding
This is the baseline for nearly every FDM and SLA job. Supports are clipped or dissolved, contact points are cleaned up, and progressively finer sandpaper grits take the surface from visible layer lines to smooth and paint-ready. Labor is the main cost driver here, so large parts and parts with deep recesses take longer.
Vapor smoothing
A chemical vapor melts the outermost surface of the part just enough to flow the layer lines together, leaving a glossy, sealed finish with no hand sanding. It works well on ABS and ASA, and dedicated systems can smooth nylon parts too. Because vapor smoothing seals surface pores, smoothed parts are easier to clean and resist moisture better — a popular choice for enclosures, housings, and wearables.
Priming and painting
For display models, trade-show prototypes, and props, we prime, fill, sand, and paint parts much like automotive body work. A properly primed and painted SLA part is usually indistinguishable from an injection-molded product, complete with matte, satin, or gloss topcoats and masked multi-color schemes.
Dyeing
SLS and MJF nylon absorbs dye readily. Dyeing colors the surface without adding any thickness, so dimensions do not change — which makes it the go-to finish for functional nylon parts that need a uniform black or a specific color.
Clear coats and sealing
Clear coats add UV and scratch resistance to painted parts, while epoxy or specialty sealants make porous prints water-tight and air-tight — important for tanks, ducts, and anything living outdoors.
What Finishing Looks Like for Each Technology
FDM parts benefit most from sanding, filling, and vapor smoothing. SLA parts always get washed and UV-cured, and with light sanding and paint they reach a near-molded finish. SLS and MJF parts are bead-blasted as a standard step and dye beautifully. DMLS metal parts typically need support removal and may get heat treatment, machining of critical surfaces, or polishing depending on the application.
How Much Time and Cost Does Post-Processing Add?
Basic cleanup and support removal is generally included in the print price. Standard finishing steps like thorough sanding, bead blasting, or dyeing usually add a modest percentage to the job. Full show-quality prime-and-paint work is labor-intensive and can add anywhere from 30% to 100% of the print cost plus one to three extra days, depending on part size and complexity. The best way to keep finishing affordable is to tell us the part’s end use up front, so we can print in the right orientation and material and finish only the surfaces that matter.
Get a Finished Part, Not Just a Print
Our Glendale studio handles printing and finishing under one roof, so you get one point of contact and one predictable timeline. Explore our 3D printing services in Los Angeles, then send us your model or a photo of the part you need finished. Call 213.489.1173 or request a quote online — we will recommend the right technology and finish for your budget and get you a fast, free estimate.