Material sheet · Composites

Glass Fiber (GF) Filament: Stiff and Stable

Plastics loaded with short glass fiber: more stiffness, less deformation and more heat resistance, at the cost of wearing down the nozzle.

Nozzle 250–270 °C 9 datasheets

Bed 82–95 °C 8 datasheets

Density 1.23 g/cm³ 15 datasheets

Tg 90 °C 8 datasheets

Drying 75 °C 5 datasheets

Glass fiber filament properties

Data taken from 16 datasheets from manufacturers in Spain, Europe, the United States and China, reviewed on October 26, 2026. The shaded bar marks the median of the declared values and each colored tick is a different datasheet. The scales are the same across the whole library, so you can compare materials at a glance.

Nozzle temperature °C · 9 datasheets

250–270 °C range 210–295

Bed temperature °C · 8 datasheets

82–95 °C range 25–110

Density g/cm³ · 15 datasheets

1.23 g/cm³ range 1.02–1.44

Glass transition (Tg) °C · 8 datasheets

90 °C range 60–158

HDT at 0.45 MPa °C · 15 datasheets

138 °C range 78–300

Vicat softening °C · 5 datasheets

95 °C range 77–98

Tensile strength MPa · 16 datasheets

59 MPa range 40–105

Tensile modulus MPa · 12 datasheets

4,208 MPa range 2,100–7,800

Elongation at break % · 14 datasheets

4 % range 2–12

Flexural strength MPa · 12 datasheets

85 MPa range 50–176

Flexural modulus MPa · 11 datasheets

4,420 MPa range 2,100–7,625

Drying temperature °C · 5 datasheets

75 °C range 60–80

Drying time h · 3 datasheets

6 h range 4–24

Spain · 0 Europe · 7 US · 5 China · 4 Band: median of the declared values

Temperature and settings for printing glass fiber

Setting	Typical value	Range in datasheets
Nozzle	250–270 °C	210–295 °C
Bed	82–95 °C	25–110 °C
Print speed	40–140 mm/s	30–350 mm/s
Drying temperature	75 °C	60–80 °C
Drying time	6 h	4–24 h

Difficulty Medium Like its matrix, but a hardened nozzle is mandatory.

Enclosed printer Recommended 1 of 1 datasheets

Hardened nozzle Required 5 of 5 datasheets

Drying before printing 75 °C · 6 h Manufacturer values for spools that have absorbed moisture.

Glass fiber vs Carbon fiber, Nylon, and Polypropylene: comparison

Setting	Glass fiber	Carbon fiber	Nylon	Polypropylene
Nozzle temperature °C	250–270	235–260	250–270	222–248
Bed temperature °C	82–95	60–82	85–100	90–105
Density g/cm³	1.23	1.25	1.11	0.93
Glass transition (Tg) °C	90	66	66	-31
HDT at 0.45 MPa °C	138	90	115	80
Tensile strength MPa	59	56	50	19
Tensile modulus MPa	4,208	5,176	1,980	1,400
Elongation at break %	4	2	13	100
Drying temperature °C	75	60	90	50

Medians from each material's datasheets. Click a material to see its full range.

Meters of Glass fiber per spool

Spool weight	1.75 mm	2.85 mm
250 g	85 m	32 m
500 g	169 m	64 m
1 kg	338 m	127 m
3 kg	1,014 m	382 m

Calculated with the median density from the datasheets (1.23 g/cm³). Real spools can vary by a few meters because of diameter tolerance.

What is a glass fiber filament

It is a composite of a plastic matrix (nylon, PETG, polypropylene, ABS…) with short glass fibers. Like carbon fiber, it stiffens the material and reduces shrinkage, but glass is cheaper, is not conductive and gives a lighter finish. The 16 datasheets analyzed cover several matrices, so the ranges are wide.

Glass fiber vs carbon fiber filament

Stiffness: carbon fiber usually gives more stiffness with less filler.
Weight: glass weighs more than carbon.
Electricity: glass fiber is an insulator, useful for electrical housings.
Abrasion: both wear down the nozzle; neither is printed with brass.

How to print glass fiber filament

Use the temperatures of its matrix (the median for the set is 250–270 °C at the nozzle and 82–95 °C at the bed), a hardened nozzle of 0.4 mm or larger and dry filament: nylon matrices are highly hygroscopic. The datasheets suggest drying at 75 °C.

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