Which filament should a beginner start with?

PLA. It prints at low temperatures, barely warps, needs no enclosure and is forgiving of a slightly wrong setting. Move to PETG when you need something tougher or a little more heat resistant.

Can I print ABS or ASA on an open printer?

Small parts, sometimes, with a draft shield or tall skirt and no air moving across the bed. Anything large will lift or crack at the layers. An enclosure is the real fix, and you still need a ventilated room.

Why does my filament hiss and pop while printing?

It has absorbed water. Steam bubbles pop as the plastic melts, leaving rough, weak layers. Nylon, PC and TPU take on moisture fastest, but even PETG and PLA do over months. Dry the spool and store it with desiccant.

Filament types explained: PLA, PETG, ABS/ASA, TPU, Nylon, PC and composites

Every spool on the shelf is a trade: how easy it prints against what the finished part can survive. This lesson walks the common FDM filaments in that order, from the forgiving to the fussy, so the next time a job says “needs to live in a hot car” or “must bend without snapping” you already know which shelf to reach for. The next lesson, picking a filament for the job, turns this into a decision table.

Temperatures below are ranges collected from the Prusa Knowledge Base and the Simplify3D materials guide. Your spool’s label wins over any number here; brands differ by 10-20 °C.

The table to keep by the printer

Filament	Nozzle	Bed	Difficulty	Softens / max use	Enclosure	Price (relative)
PLA	190-230 °C	45-60 °C	easiest	above about 60 °C	no	cheapest
PETG	230-250 °C	75-90 °C	easy	below about 80 °C	no	cheap
ABS	220-255 °C	95-110 °C	medium-hard	good heat resistance	yes	cheap
ASA	about 250-260 °C	100-110 °C	medium-hard	up to about 93 °C	yes	mid
TPU (flexible)	225-245 °C	45-75 °C	hard (slow)	rubbery, not a heat material	no	mid
Nylon (PA)	225-285 °C	70-110 °C	hard	high	recommended	expensive
PC	260-310 °C	80-120 °C	very hard	glass transition about 150 °C	yes	expensive
CF / glass filled	240-285 °C (base + ~10 °C)	as base	medium	slightly above base	as base	expensive
Wood filled (PLA base)	190-220 °C	45-60 °C	medium (clogs)	as PLA	no	mid

“Softens” is the temperature where a loaded part starts to deform, not where it melts. A shelf bracket at 50 °C in a sunlit window is already a problem for PLA.

The more heat it takes, the harder it is to print; start with PLA and move up

PLA: the default

Plant-based, prints at the lowest temperatures, barely warps, holds fine detail and needs little bed heat (60 °C helps). Stiff with good strength, which is why calibration cubes and accurate assemblies are printed in it. Its limits: it softens above about 60 °C, turns brittle in sunlight over time, and is hard to post-process. Prusa’s advice is blunt: concept models, toys, decoration, not technical or outdoor parts. Cooling fan at 100 % after the first layers.

PETG: tougher, a little hotter

Bottle plastic with glycol added so it prints. Good layer adhesion, tough rather than stiff, low warping, water resistant, usable below about 80 °C. The costs: stringing (fine hairs between features), poor bridging, a softer surface that scuffs, and it bonds so hard to a smooth PEI sheet that it can tear the coating off. Use a textured sheet or a layer of glue stick as a release agent. The fix for stringing is more retraction and a cooler nozzle, which lesson 7 covers.

ABS and ASA: heat, with conditions

Both are styrene plastics that handle heat and impact well and can be sanded, glued and vapour-smoothed with acetone. Both shrink as they cool, roughly 1-2 % for ABS, which shows up as warping, lifted corners and split layers on anything large. That is why the bed runs at 100 °C or more and an enclosure is recommended, with the Prusa guide calling it necessary for large parts. Both release styrene while printing: ventilate the room, but keep drafts off the bed.

ASA is the newer sibling: high UV resistance, so outdoor parts do not yellow and crack the way ABS does, less odour and a little less warping, with a usable temperature up to about 93 °C. If you only stock one of the two, ASA.

TPU: the one that bends

Thermoplastic polyurethane, a rubber-like filament rated by Shore hardness, typically 60A-90A; softer means harder to print. It is tough, dampens vibration and has good layer adhesion and low shrinkage. The catch is feeding a soft noodle through an extruder: direct drive is much easier than a Bowden tube, speed is around 20 mm/s with 30-40 mm/s as a ceiling, retraction starts at zero and is raised only if stringing demands it, and the cooling fan goes off or low. Bridging and overhangs are poor, supports are hard to remove, and it absorbs moisture. Phone cases, feet, gaskets, grip sleeves.

Nylon (PA): tough, slippery, thirsty

Strong, abrasion resistant, low friction, tough in thick sections and flexible in thin ones; no bad smell, but ultrafine particles that still want ventilation. The two problems are warping (an enclosure helps a lot) and water: nylon can absorb up to 10 % of its weight, and wet nylon foams, bubbles and prints rough and weak. Dry at least 4 hours below 90 °C and store airtight with desiccant. Gears, bushings, clips, cable ties. Carbon-fibre-filled nylon warps far less and can be printed open.

PC: the top of the heat ladder

Polycarbonate is impact and heat resistant, bendable without breaking and transparent when pure, with a glass transition around 150 °C. It asks for everything: nozzle 260-310 °C (all-metal hotend), bed 80-120 °C, enclosure, a release layer so it does not rip the sheet, and it is extremely hygroscopic. Pure PC is advanced-user territory; blended PCs sold for FDM are much easier. Fan shrouds, electronics housings near heat, parts that must not shatter.

Composites: fibre and wood

A composite is a base plastic (PLA, PETG or nylon) with something mixed in.

Carbon, glass or Kevlar fibre raises stiffness, dimensional stability and heat resistance and gives a matte look, but lowers layer adhesion and impact resistance, makes the filament brittle and clogs more. The fibres are harder than brass, so a hardened steel nozzle is required; 0.4 mm and 0.2 mm layers are the smallest sensible values.
Wood or metal powder is cosmetic. Wood-filled PLA prints at PLA temperatures but the particles clump in small orifices: use a 0.5-0.6 mm nozzle and 0.2 mm layers, and expect weaker parts and more oozing. Metal fill is also abrasive and needs a hardened nozzle.

A worked example: reading the spool

A new 1 kg spool of PETG arrives labelled “nozzle 230-250 °C, bed 70-80 °C”.

First layer at the top of the range, 250 °C, for bed grip. Later layers mid-range, 240 °C, and drop by 5 °C steps if stringing appears.
Bed 80 °C on a textured sheet. On a smooth PEI sheet, glue stick first.
Fan on from layer 3, moderate rather than full, since PETG wants less cooling than PLA.
Check the printer: PETG needs no enclosure and no hardened nozzle, so any machine will do.

Now the same exercise with nylon that spent a month on an open shelf. At up to 10 % water uptake, a 1 kg spool could be carrying up to 100 g of water; even 2 % is 20 g, enough to foam every layer. Dry it 4 hours below 90 °C and weigh it before and after. A spool that loses 15 g was far wetter than it looked.

Safety

Nozzles run 190-310 °C and beds up to 120 °C across this table. Do not touch either during or just after a print.
ABS, ASA and nylon release fumes or fine particles. Ventilated room, no draft on the print, or an enclosure with filtration.
Dry filament in a dedicated dryer or a controlled oven, never above the filament’s softening point, and never leave it unattended.
Keep flammable material away from the printer, and watch a new material’s first layers.

Common mistakes

Using the slicer’s generic profile temperature instead of the range printed on the spool.
Printing PETG on a smooth PEI sheet with nothing between them. The part takes the coating with it.
Printing ABS or ASA in a closed room because the enclosure “contains” the fumes. It does not.
Running carbon-fibre filament through a brass nozzle. It works for a while, then every dimension drifts as the orifice widens.
Treating “waterproof” PETG as “does not need drying”. The part resists water; the spool still absorbs it over months.

With the shelf understood, the next step is matching a spool to a job: heat, sun, load, flex, looks or ease. That is lesson 6.

Sources

Circuits and code were tested on sample boards. Boards differ in pin layout, so check your board's pinout before you power anything.