Once your 3D printer stops moving, the job isn’t finished. What you do in the next few minutes and hours determines whether your print looks great, lasts long, and whether your printer is ready for the next job. The steps depend on whether you’re working with filament (FDM) or resin (SLA/MSLA), but every print needs some form of post-processing.
Let the Print Cool Before Removing It
For filament prints, patience pays off. Pulling a print from a hot build plate risks warping the base, leaving material stuck to the surface, or delaminating the first layer. Most experienced printers wait until the bed drops below 35°C before touching anything. If you’re printing with a thin base or a part with a large footprint, aim for 30 to 35°C to minimize any chance of warping.
PETG is especially sensitive. Removing it above 60°C can cause the first layer to delaminate and fuse to the bed, which is a headache to clean up. ABS and ASA should cool inside a closed enclosure to prevent warping from rapid temperature changes.
For removal, a plastic razor scraper is all you need in most cases. Slide it under a corner, apply gentle upward pressure, and the part should pop free. Metal scrapers work but risk scratching your build plate over time. If a print is truly stuck, you can try blowing compressed air around its base to speed up cooling rather than forcing it off.
Wash and Cure Resin Prints
Resin prints come off the build plate coated in uncured liquid resin, which is toxic to skin and harmful to the environment. Wear nitrile gloves every time you handle uncured resin, and work in a well-ventilated space.
The standard cleaning method is a bath in isopropyl alcohol (IPA) at 90% concentration or higher. Submerge the print and swirl it gently for 2 to 5 minutes, depending on size and complexity. That window matters: soaking too long softens fine details, causes micro-cracks, or warps flexible sections. Some delicate resins need even less time. Siraya Tech’s Simple Resin, for instance, should only contact alcohol for about 30 seconds per rinse, cleaned in quick cycles totaling 2 to 3 minutes.
After washing, let the print air dry completely, then UV cure it. A curing station with LEDs in the 385-nanometer range offers a good balance between surface hardness and even curing throughout the part. Cure times vary by resin brand, but most standard resins need 2 to 10 minutes per side under adequate UV light. Under-cured resin stays tacky and weak; over-cured resin becomes brittle.
Remove Supports Carefully
Supports are necessary evils on both FDM and resin prints, and removing them poorly leaves scars on your finished surface. The key is using the right tools and controlled force.
For FDM prints, start with flush cutters or needle-nose pliers to snap off the bulk of the support structure. Grip close to the contact point and apply steady, gentle pressure rather than twisting. For PLA, you can apply mild heat from a heat gun or hair dryer to soften stubborn supports, making them less brittle and easier to detach without tearing the surface underneath. Finish up with a craft knife to trim any small nubs or remnants.
Resin supports are thinner and snap off more easily, but the contact points can still leave small pockmarks. Clip them with flush cutters before curing if possible, since uncured resin is softer and more forgiving. A craft knife handles the final cleanup.
Sand for a Smooth Finish
Layer lines are the telltale sign of a 3D print. Sanding removes them. The trick is starting coarse and working your way up through progressively finer grits, never skipping more than one step.
For PLA, start at 120 to 150 grit for rough shaping, move to 220 to 320 for removing visible layer lines, then 400 to 600 for smoothing. If you want a paintable or polished surface, finish with 800 to 1000 grit or higher.
Resin prints are already smoother off the printer, so you can start at 220 grit and progress through 320 to 400, then 600 to 800, and all the way up to 2000 grit for a near-glass finish.
Wet sanding (keeping the sandpaper and surface damp) reduces heat buildup and prevents plastic dust from clogging the paper. It also produces a more even result. Wear a dust mask or particulate respirator while sanding dry, since fine plastic particles are not something you want in your lungs.
Prime and Paint
If your print is destined for display, priming is the bridge between raw plastic and a professional-looking paint job. Primer fills in minor surface imperfections, gives paint something to grip, and creates a uniform base color so the final coat looks even.
Use a primer labeled as plastic-compatible, and ideally match the primer and paint to the same brand. Tamiya’s spray primers are a popular choice among hobbyists because they go on thin enough to preserve fine surface detail. Krylon and Montana work too, though they apply thicker. For resin prints, Tamiya’s TS line of synthetic lacquers bonds well to cured resin and transitions smoothly to clear coats or hand-painted acrylics on top.
Apply primer in light, even passes from about 15 to 20 centimeters away. Two to three thin coats beat one thick one. Let each coat dry for the time listed on the can before adding the next. Once the final primer coat is dry, lightly sand with 800 grit or higher to knock down any texture, then move on to your color coats.
Clean the Printer for Your Next Job
A quick cleanup after every print prevents problems on the next one. Oils from your fingers, leftover filament bits, and adhesive residue all interfere with first-layer adhesion.
Turn off the printer and let the bed cool completely before cleaning. Never clean a hot build plate, as it can warp removable plates and risks burns. Remove any loose filament scraps or failed support material, then wipe the build surface. For PEI and similar textured sheets, isopropyl alcohol on a lint-free cloth works well. Avoid household cleaners containing ammonia, which can leave residue and degrade PEI and BuildTak surfaces over time.
Check your nozzle for any filament oozing or buildup. A quick cold pull (heating the nozzle, inserting filament, cooling it, then pulling it out) clears partial clogs before they become full blockages. Make sure the bed is completely dry before starting your next print.
Strengthen PLA With Heat Treatment
Standard PLA starts softening around 60°C, which limits its usefulness for parts that see heat or mechanical stress. Annealing (controlled heating in an oven) increases both strength and heat resistance by allowing the plastic’s internal structure to crystallize more fully.
Research on optimizing this process found the best results at 90°C for 120 minutes, producing notable improvements in tensile strength, flexural strength, compressive strength, and impact resistance. The trade-off is dimensional change: annealed parts can shrink or warp slightly, so this technique works best on parts where you can account for that in your design. Use an oven thermometer to verify the actual temperature, since household ovens can swing 10 to 15 degrees from their displayed setting.
Dispose of Resin Waste Safely
Uncured resin and contaminated IPA are hazardous waste. Never pour them down a drain or toss them in household trash.
For liquid resin you need to discard, cure it first. Spread it in a thin layer on a disposable surface and leave it in sunlight or under a UV lamp until fully hardened. Cured, solid resin is generally safe for regular waste.
Used IPA is trickier. It contains dissolved methacrylated monomers (unpolymerized plastic) and trace photoinitiators. In most jurisdictions, this qualifies as chemical waste. Check your local hazardous waste disposal options, as many municipalities run periodic collection events. For larger volumes or commercial use, a licensed waste disposal service is the standard route. If you let contaminated IPA sit in sunlight, the dissolved resin will cure and settle out, extending the solvent’s useful life, but the IPA still needs proper disposal once it’s too saturated to clean effectively.