PLA.
THE DEFAULT.
PLA (polylactic acid) is where almost everyone starts in 3D printing, and for good reason: it's forgiving, dimensionally accurate, comes in a thousand colors, and doesn't stink when it prints. If you're new to custom printing or just want a part that looks good on a shelf, PLA is probably what you want.
But PLA also has a hard ceiling — literally. It softens around the temperature of a hot car dashboard, which means it's a terrible pick for anything that lives outdoors in Florida, under the hood of a vehicle, or near a heat source. Picking the right filament is mostly a question of knowing where PLA stops.
What it is
PLA is a thermoplastic made from fermented plant starch — usually corn or sugarcane. That origin story is why it gets called "bioplastic" or "eco-friendly" in marketing copy. It's true that the feedstock is renewable, but the "compostable" claim needs an asterisk: industrial composting facilities at 55–60°C can break it down in months, but backyard compost and landfills will hold PLA for decades. Call it "less bad" rather than "green."
Mechanically, PLA is stiff and brittle. It resists bending very well, which makes it dimensionally accurate — but when you push it past its limit, it cracks rather than flexes. Think of it as being closer to bone than rubber.
Technical properties
- EXTRUDER TEMP
- 190 – 220 °C
- BED TEMP
- 50 – 60 °C (or none)
- ENCLOSURE
- Not required
- GLASS TRANSITION
- ~ 60 °C — softens
- HEAT DEFLECTION
- ~ 55 °C
- TENSILE STRENGTH
- ~ 50 – 65 MPa
- ELONGATION
- ~ 3 – 6 % (brittle)
- IMPACT RESIST.
- Low — chips under shock
- UV RESIST.
- Poor — yellows and weakens in sunlight
- WATER ABSORB.
- Low (~0.3 %)
- ODOR
- Faintly sweet during printing
Pros
- Easiest material to print. Low warp, low temperatures, no enclosure needed. First-layer success rates are nearly 100 % on a well-tuned printer.
- Extremely dimensionally accurate. Because it cools fast and doesn't contract much, PLA holds its dimensions better than almost any other filament. This matters for threaded holes, mating surfaces, and press-fits.
- Crisp surface detail. Fine features, text, and small geometry print beautifully. For display models, figurines, and cosplay props, nothing beats PLA.
- Huge color selection. Every brand makes PLA in every color imaginable — matte, silk, glitter, translucent, glow-in-the-dark, marble, color-shift. If aesthetics matter, PLA wins.
- Low printing smell. Safe to run in an office or bedroom (still ventilate — all FDM printing emits ultrafine particles).
- Rigid and stiff. If you need a part that won't flex, PLA resists bending forces better than PETG or TPU.
- Cheap. Among the least expensive filaments on the market.
Cons
- Heat intolerance is the dealbreaker. PLA starts to sag at about 55 °C. A car left in the sun in Orlando in July hits 70 °C on the dash in twenty minutes. A closed garage hits 50 °C easily. If the part will ever see that, PLA is wrong.
- Brittle. Drop a PLA part on concrete and it may crack or shatter where a PETG part would just scuff.
- Poor UV resistance. Sunlight makes PLA yellow, become chalky, and lose strength over months.
- Creeps under long-term load. Leave a PLA part under steady weight for weeks and it will slowly deform even at room temperature.
- Not truly food-safe. Food-contact claims depend on the colorant, the brand, and the layer porosity. We do not recommend PLA for repeated-use food containers.
- Hard to glue and sand. Most adhesives don't bite; cyanoacrylate (super glue) works best. Sanding gums up the plastic.
When to pick PLA
Choose PLA if any of these are true:
- The part is a prototype, model, or iteration you're going to throw away in a month.
- Appearance matters more than durability — figurines, display pieces, cosplay, tabletop miniatures.
- The part lives indoors, at room temperature, out of direct sunlight.
- You need fine detail — small text, intricate features, smooth curves.
- You're on a tight budget and the part won't take mechanical abuse.
- You're making something for a school project, a gift, or a one-time event.
When not to pick PLA
- Anything that will see the inside of a car in summer.
- Parts exposed to direct sunlight for months.
- Load-bearing brackets that will hold weight for long periods.
- Threaded parts that will be tightened and loosened repeatedly.
- Outdoor tools, garden hardware, anything in the heat or rain.
- Gaskets, grips, or anything that needs to flex.
- Food containers you plan to microwave or dishwash.
If the part is borderline, we'd nudge you toward PETG: it's slightly harder to print but survives everyday use far better.
Design tips for PLA parts
- Because PLA is brittle, avoid sharp internal corners and thin walls under 1.2 mm on structural parts. Use fillets (rounded corners) wherever loads concentrate.
- Bolt holes should be sized 0.2–0.3 mm oversize. PLA doesn't flex — it splits.
- For parts that will be handled, orient print lines perpendicular to expected drop impacts. Layer lines are the weakest axis.
- Fill at 15 – 20 % is plenty for display parts. Jump to 30 – 40 % if the part will see hand pressure or light load.
- Don't design PLA parts with moving hinges that snap — they'll crack within a few dozen cycles. Use TPU or PETG for living hinges.
Our take
PLA is an honest material when used honestly. It fails when people ask it to be something it isn't — a structural bracket, a car interior component, an outdoor enclosure. If you're printing for display, for a gift, for a prototype, or for something that lives on a shelf, PLA is almost always the right call and will give you the sharpest-looking result.
At Spool Foundry we print PLA on every job where the customer hasn't specified otherwise and the part's intended use doesn't rule it out. It's our workshop default for a reason.
Still not sure?
Tell us what the part does, where it lives, and whether it sees heat or load. We'll recommend the right plastic for free — no obligation — through our contact form.