PETG

PETG is tougher than PLA, survives more heat, and is the material most G1 production work runs on. It is also the one that asks for the most attention: it is highly hygroscopic, and it sticks to the extrusion screw, which is where most PETG problems on this machine actually come from.

The grade decides the numbers, not the polymer

Every figure on this page is a starting point. PETG grades differ in melt viscosity, and additives — fibre, flame retardant, colour — shift it further. The authority for temperatures, drying and flow is the datasheet for the grade in your hopper.

Ginger Additive does not manufacture pellets. Supply runs through Formfutura and Polymaker PolyCore — see where to buy.

Pros and cons

Good	Less good
Tough, far less brittle than PLA	Highly hygroscopic — drying is mandatory, not optional
HDT above 70°C, against PLA’s ~50°C	Cakes onto the screw without SmoothFlow
Excellent layer adhesion when properly dried	Strings more than PLA
Tolerates sitting in the extruder longer than PLA
Clear grades stay transparent	Bonds to glass hard enough to chip it
Wide grade range: fibre-filled, flame-retardant, coloured	Needs a heated bed; more warping than PLA

Starting parameters

These are the values in Ginger Slicer’s own profiles. They are the only figures that count: the slicer is what sends temperatures to the printer, so a number written anywhere else is a copy that can drift.

Profile	Zone 1	Zone 2	Zone 3	Bed	MVS
Generic PETG	220	240	240	80	200
Azure PETG	210	210	210	80	250
FormFutura rPETG	215	235	235	80	200
FormFutura rPETG 10GF	205	225	225	80	200
FormFutura rPETG 20GF	220	235	245	80	200
Generic PETG GF	220	235	245	80	200
Polymaker PETG 10GF	190	230	240	80	200
Polymaker PETG 20GF	220	230	240	80	200

Pick the profile for the pellet you are running. If there is no profile for your grade, start from Generic PETG and copy it before changing anything — see Material profiles.

Other settings
SmoothFlow	Effectively required. Dose is in SmoothFlow — one place, so it cannot drift
Drying	Mandatory — 60–70°C, at least 4 h, 6 h recommended. Even from a freshly opened sealed bag

Never raise the Feeding Zone to clear a clog

PETG is the material that most readily plugs the barrel inlet, and that plug is caused by heat: at low flow there are not enough pellets moving through to carry heat away, so the material softens at the inlet and compacts into a block.

Raising the temperature to shift it feeds the cause. Come down on the top zone — always, for this fault. Full mechanism and how to clear it: Nozzle and barrel clog.

That rule is about a clog. “The screw turns and nothing comes out” has a second cause that looks identical and wants the opposite: too much SmoothFlow or Liquid Masterbatch makes the pellets slip instead of gripping. The tell is the motor: a clog makes it work and skip, slippage does not — the screw turns freely and nothing arrives.

On the 1.8 mm nozzle the flow is slow enough that this bites at normal settings — drop the Feeding Zone to around 190°C while leaving the other two zones alone.

Drying, and watching the dryer

Drying is not optional for PETG. 60–70°C depending on the grade, 4 hours minimum, 6 recommended.

Check it has not packed in the dryer

Left in the dryer too long, PETG can compact in the hopper. Check on it: the sign is not a print defect but the printer running out of material while the dryer still looks full, because nothing is dropping out. See Starting the dryer.

Its two real problems

Everything else about PETG is easy. It prints readily, tolerates sitting in the extruder longer than PLA, and clogs less — though a slow print can still plug the inlet. What actually causes trouble is that it sticks ferociously to hot surfaces, and there are two of those on the machine.

1. It cakes onto the screw

PETG welds itself to the steel in the upper part of the screw. Once that happens the torque needed to turn the screw exceeds what the motor can give, and the material becomes unprintable — it reads as an MVS or motor problem, and it is neither.

The fix comes from injection moulding, where an oil is blended with the pellets for the same reason. On the G1 the product for this is SmoothFlow:

• Start at 0.05% — 0.5 g per 1 kg of pellets, and never go above 0.1%. See SmoothFlow
• Mix it thoroughly through the pellets before printing, not on top of a full hopper

That is enough to stop the material adhering in the upper screw. Liquid Masterbatch lubricates too, since it is oil-based, so a coloured run may need less.

2. It bonds to the glass and chips it

PETG grips the print surface hard enough to pull chips out of the glass when a part is removed. This damages the bed, not just the print.

Use a spray. DimaFix is the one to reach for: it holds the part while the bed is hot, then releases as the bed cools at the end of the print, so the part comes away without taking the glass with it.

What PETG is good at

• Fully transparent in clear grades
• Excellent layer adhesion — the strongest of the two polymers on this machine
• HDT above 70°C, against PLA deforming around 50°C
• Glass-fibre filled PETG is the most dimensionally accurate material on the G1 — if the part has to hold a tolerance, that is the grade to use

Grades

Clear and coloured

Clear grades stay transparent and suit light-pipe and decorative work. Pre-compounded coloured pellets need no Liquid Masterbatch.

Glass-fibre reinforced (PETG GF)

The usual choice for large structural and outdoor parts. Fibre cuts warping sharply and holds dimensions over time and temperature, at a fraction of the cost of PA or PC.

Fill	When
10% GF	Better rigidity than plain PETG with a still-smooth surface — start here when the part is visible
20% GF	Maximum stability and warp resistance; the surface is rougher and visibly fibrous

GF pellets usually arrive with a white pigment. For colour, ask the supplier for a GF natural or GF clear base and add Liquid Masterbatch; solid masterbatch needs about 2% to come out homogeneous and shifts viscosity slightly.

Flame-retardant grades

Two ratings turn up, and they are different standards rather than different strengths of the same one:

Grade	Standard	Meaning
V0	UL94	Self-extinguishing within 10 s, no flaming drips. The stricter of the two
B1/S1/D0	EN 13501-1	European construction rating: low flammability, low smoke, no burning droplets

Both need care:

• They absorb moisture faster than standard PETG. Dry longer — 6–8 h at 65–70°C. Yellowish pellets, or a visible bubble inside a granule, mean the batch is wet
• They stick to the screw more. SmoothFlow or Liquid Masterbatch is effectively required
• Do not assume standard PETG temperatures. The retardant package changes the melt viscosity, and V0 in particular tends to run cooler
• Batch consistency varies more than on plain grades — test before committing to a production run

Emissions from filled and flame-retardant grades are not well characterised in the published literature. Get the SDS for the specific grade: the additive package is what carries the hazard. See Safety and fumes.

Common issues

Symptom	Cause and fix
Foaming, bubbles, popping	Wet pellets. See PETG foaming and moisture
Screw turns, nothing extrudes	Plug at the barrel inlet. Take the hopper off and lift it out, then lower the Feeding Zone. See Nozzle and barrel clog
Motor skipping at high flow	Missing SmoothFlow before it is an MVS problem. See Extruder motor skipping
Part will not come off the glass	It bonded. Let the bed cool fully, or use a release agent — see Bed adhesion sprays
First layers milky on clear PETG	Bed too hot
Stringing between parts	Tune retraction in Ginger Slicer

Storage

• Reseal the bag the moment you finish, with desiccant inside
• Never leave pellets sitting in an open hopper between prints
• Re-dry after any pause longer than 24 h

Supply

Stock comes from Formfutura — clear, GF 10%, GF 20%, and both flame-retardant grades — and Polymaker PolyCore (PETG-1000 / 1013 / 1211). Contact Formfutura sales for volume supply.

Most GF suppliers buy base resin from the same few petrochemical producers; what differs between them is fibre quality and how evenly it is blended.

Related notes

• PLA
• SmoothFlow
• Liquid Masterbatch
• PETG foaming and moisture
• Nozzle and barrel clog
• Starting the dryer
• Max Volumetric Speed