Guide to Post-Processing and Finishing SLA Resin 3D Prints

Stereolithography (SLA) prints are a go-to way of modeling products for business owners, chemists, and hobbyists alike, because they deliver lifelike prototypes and miniatures that are smooth and waterproof. But a raw print straight off the machine is not the finished article. A designer usually needs to spend real time working the kinks out of a fresh SLA print.

There are five main processes to complete before a print is ready to use: washing, curing, sanding, painting, and electroplating. This guide walks through each one, plus removing prints and handling supports, with practical tips along the way. For the technology itself, see our guide to SLA printing.

Tools You Will Need

Unlike FDM prints, SLA post-processing calls for a few specific materials. A solid starter kit includes:

• Plastic sheets and drying towels
• Nitrile or neoprene gloves
• Isopropyl alcohol (IPA)
• An ultrasonic cleaner and a turntable
• UV lighting for curing
• Flush plier cutters and a spatula or print removal tool
• Sandpaper and acrylic paint

Removing the Print

Fresh prints are vulnerable, so remove them with care:

1. Lay down paper towels or plastic sheets to catch drips.
2. Put on gloves before handling to protect the print and your skin.
3. Gently lift the build plate off the printer without knocking the model.
4. Slide a spatula under an edge, then use a removal tool to lift the print free.

Handling Supports

A support structure has three parts: the raft that anchors it to the build plate, the scaffolding that holds the model upright, and the connector points where they meet the design. Overhangs, protruding edges, and fine details usually need them. You can clean supports before or after curing, though post-curing takes more care. Use flush cutters held tight against the model to snip each beam cleanly, with patience and a steady hand.

Washing

Washing removes sticky uncured resin so the model responds well to curing and sanding. The cleanest method is an ultrasonic cleaner, which does the work without handling. If that is out of budget, submerge the print in IPA with gloved hands, since most resin chemicals are skin irritants until fully cured.

Washing tips

IPA gives the most effective results, so buy it in bulk. For small crevices, a syringe clears out trapped resin better than soaking. When in doubt, wash a part more than once.

Curing

Curing places the print under UV light so the polymerization reaction fully hardens the resin. Skipping it can leave a spotty, under-formed result, and proper curing also makes the model easier to sand.

Curing tips

Give each part a set time under the light and rotate it for even coagulation. A curing machine handles this automatically, but plain sunlight can cure a print if you do not want to invest in one, though weather affects how well it works.

Sanding

Sanding is the preferred way to reach a smooth, blemish-free surface and remove leftover support marks. Fill hollow models first for stability so they do not dent or warp. Use sandpaper for detailed pieces and small power tools for bulkier ones.

Sanding tips

Start with low-grit paper to knock down support marks and protrusions, then step up to finer grits. Around 3000 grit yields a smooth, glossy finish on most designs, and wetting the paper helps on stubborn spots. SLA parts need far less sanding than FDM prints. Wipe the print with a soft cloth when done.

Coloring

Once smooth, you can bring the model to life with color. There are several approaches:

Dyed resin (pre-dyeing)

Mix alcohol ink into clear resin for consistent color throughout the print, applying it with syringes for precise measurement. Label every wash solution so you do not mix them up, and take extra care washing, since IPA can affect colored resin.

Post-dyeing

Submerge finished parts in a dye solution for a quick color change. It is less permanent than pre-dyeing but far more flexible, letting you color separate parts differently and clean up more easily.

Acrylic and spray paint

Acrylic painting gives you maximum artistic control over every detail, at the cost of time. Spray paint is faster and, in skilled hands, can look better than dyeing; start with thin coats and build up. Our guide to color in 3D printing covers these methods in more depth.

Electroplating

The final optional step is electroplating, which deposits metal ions on the surface to make the print far more resistant to wear, corrosion, and UV. SLA parts are often less durable than filament prints, so this is worth it if the piece is functional rather than purely decorative, and it is much cheaper than printing in metal. The process runs through cleaning, pre-dipping, etching, optional conditioning and neutralizing, activation, and an electroless bath that lays down a thin metallic coat, usually nickel or copper.

From Raw Print to Finished Model

Wash, cure, sand, color, and optionally electroplate, and your raw SLA print becomes a polished, usable model. Take your time with each step and you will get results worthy of a client or a display shelf. For more guides and recommendations, explore the resources at 3DGearZone.