Why SLS Parts Need Finishing
Fresh SLS parts usually come out with a matte, powdery texture. They may be fully functional after depowdering and blasting, but appearance, feel, color, sealing, and fit often improve with finishing. The right finish depends on whether the part is a prototype, internal tool, consumer product, or functional assembly.
Why SLS Parts Need Finishing
Fresh SLS parts usually come out with a matte, powdery texture. They may be fully functional after depowdering and blasting, but appearance, feel, color, sealing, and fit often improve with finishing. The right finish depends on whether the part is a prototype, internal tool, consumer product, or functional assembly.
Finishing is not cosmetic fluff. It can affect dimensions, friction, cleanability, water behavior, and customer perception. Plan finishing before ordering parts, especially when tolerances matter.
Depowdering and Media Blasting
The first finishing step is removing loose powder. Operators brush, vacuum, air blast, or use dedicated depowdering stations depending on the system. Media blasting then removes remaining powder and evens the surface.
For many internal functional parts, this may be enough. A fixture, hidden bracket, or prototype housing may not need dyeing or smoothing. Keeping the finish simple lowers cost and preserves dimensions.
Dyeing
Dyeing is common for nylon SLS parts, especially black dye for a more finished appearance. It can make parts look more consistent and hide handling marks. Color options depend on material, supplier, and part geometry.
Dyeing does not fix poor geometry or surface defects. It is best used after the part has been cleaned and inspected. For customer-facing parts, request samples because color can vary across batches and materials.
Tumbling and Media Polishing
Tumbling and media polishing smooth the surface by gently wearing down high spots. This can improve touch feel and appearance, but it can soften edges and change small features. Raised text, fine teeth, and snap details need caution.
Use tumbling when a smoother matte finish matters more than crisp micro-detail. For precise mechanical features, mask, avoid, or post-machine critical areas after finishing.
Vapor Smoothing
Vapor smoothing uses controlled solvent vapor to smooth and seal compatible polymer surfaces. For SLS nylon, it can create a glossier, less porous, easier-to-clean finish. Formlabs describes vapor smoothing as one of the options after cleaning and media blasting.
The tradeoff is dimensional and visual change. Sharp edges can soften, small details can lose definition, and the surface may become glossy rather than matte. It is a strong option for consumer-facing enclosures, handles, or parts that need easier cleaning.
Coating, Painting, and Sealing
SLS parts can be sealed, painted, primed, or coated when color, moisture behavior, chemical resistance, or branding matters. Coatings add thickness and can affect threads, slots, snap fits, and mating surfaces.
If a part needs paint, design with sanding and handling in mind. Broad accessible surfaces are easier to finish than deep ribs and hidden cavities. Mask critical features before coating whenever fit matters.
Choosing the Right Finish
For internal tools, depowdering and blasting may be enough. For visible functional parts, black dye and light tumbling often provide a practical balance. For consumer products, vapor smoothing, sealing, or painting may be worth the added cost.
Always match the finish to the part’s job. A glossy sealed surface may be useful for a handheld product, while a slightly textured raw nylon surface may be better for a fixture that needs grip.
FAQ
What is the most common SLS finish?
Depowdering and media blasting are the basic finish. Dyeing, tumbling, sealing, and vapor smoothing are added when appearance or function requires them.
Can SLS parts be smoothed?
Yes. Tumbling, media polishing, and vapor smoothing can improve surface feel, but they may soften edges or affect dimensions.
Does SLS finishing change part size?
It can. Tumbling removes material, coatings add thickness, and smoothing can soften details, so critical fits should be checked after finishing.
