Borosilicate Glass FDM Filament

Pyrex® (Borosilicate) Glass Filamet™ — 1.75 mm, 0.5 kg

Print real translucent borosilicate glass on the FDM printer you already own. After kiln firing, your print fuses into genuine Pyrex®-grade glass — the same heat-resistant lab glassware you sterilise, bake and run reactions in.

69–72% Borosilicate Real Translucent Glass Lab Glassware Grade Slumps & Fuses 0.8 mm Nozzle Required
The Virtual Foundry Pyrex Borosilicate Glass Filamet 1.75mm 0.5kg spool

Real borosilicate glass, printed on a desktop FDM printer

Pyrex® (Borosilicate) Glass Filamet™ is a 69–72% loaded borosilicate filament — the same low-expansion glass chemistry used in laboratory beakers, kitchen ovenware and optical research components. After kiln firing, the polymer binder burns out and the glass particles slump and fuse into genuine, translucent borosilicate.

Unlike TVF’s metal and ceramic Filamets, glass does not densify through powder sintering. Instead the glass softens, slumps under gravity and fuses with itself — a fundamentally different physical process. That changes how you design parts, support geometry and ramp the kiln.

Glass behaves differently to metal or ceramic. Metals densify through solid-state sintering. Ceramics vitrify or sinter depending on chemistry. Glass fuses — it goes through a viscous liquid state where surface tension and gravity reshape your geometry. Treat tall, thin or unsupported features with caution.

How it works — the 4-step glass workflow

1

Print

Print on any FDM printer fitted with a 0.8 mm hardened steel nozzle. Glass requires a larger nozzle than other Filamets — particle size demands it.

2

Pack & Support

Nest the green part in a refractory bed shaped to support the geometry through fusing. Unsupported overhangs will slump under gravity once the glass softens.

3

Fuse

Fire to ~820–850°C. The binder burns out and the borosilicate particles slump together and fuse — this is glass forming, not metal sintering.

4

Anneal & Finish

Slow-cool through the annealing range to relieve internal stress. Finished glass can be ground, polished or further worked with standard glassworking tools.

Why borosilicate glass

Genuine Pyrex®-grade chemistry

Low-expansion borosilicate — the same glass family used in lab beakers, oven dishes and reaction vessels. Thermal shock resistant by composition.

Translucent finish

Fired parts are translucent — not the opacity you get from metals or most ceramics. Excellent for optical research, light pipes and decorative work.

Chemically inert

Resistant to most acids, solvents and reagents. Ideal for prototype lab vessels, fluidic test rigs and chemistry-adjacent jigging apparatus.

Print — don’t blow

Skip the lampworking torch. Geometry that would take a glassblower hours becomes a slicer task you queue overnight.

Bonds with traditional glasswork

Printed borosilicate fuses to lampworked borosilicate. Use FDM for jigs, substrates and base shapes; finish with traditional glasswork.

USA-made, fully supported

Manufactured in South Central Wisconsin by The Virtual Foundry. Direct technical support from the team that makes the material.

Printing tips

  • 0.8 mm hardened steel nozzle is mandatory — smaller will jam
  • Direct drive strongly preferred for this stiffer filament
  • Filawarmer strongly recommended — resets spool memory
  • Design refractory supports for the kiln, not just printed supports
  • Plan for slumping — tall, thin or unsupported features deform during fusing

Common applications

  • Lab glassware prototypes — vessels, fittings, manifolds
  • Jigging apparatus for shape-memory alloy development
  • Optical research components and light pipes
  • Decorative glass art and sculpture substrates
  • Scientific instrumentation prototypes
  • Lampworking jig substrates — FDM-print, then torch-finish

Specifications

Specification Details
Glass content (post-fire) 69.0–72.0% borosilicate glass
Glass family Borosilicate (Pyrex®-grade chemistry)
Filament density 1.45–1.55 g/cc
Diameter 1.75 mm (±0.05 mm)
Spool weight 0.5 kg
Firing temperature ~820–850°C (slump & fuse, not solid-state sinter)
Required nozzle 0.8 mm hardened steel (LARGER than other Filamets)
Linear shrinkage (post-fire) Geometry-dependent — glass slumps rather than uniformly shrinks
Hygroscopicity Less hygroscopic than PLA — do NOT dry
Origin Made in South Central Wisconsin, USA

What you can make

Pyrex borosilicate glass spool
Pyrex® Borosilicate Glass Filamet™ on a 0.5 kg spool
Pyrex Filamet half spool
Genuine borosilicate — from FDM print to fused glass

Frequently asked questions

Why does this filament need a 0.8 mm nozzle?

The borosilicate particles in Glass Filamet™ are coarser than the metal and ceramic powders TVF uses elsewhere. A 0.6 mm nozzle — the standard for the rest of the range — will jam very quickly. The 0.8 mm hardened steel nozzle is the minimum that reliably passes the glass loading.

How is glass firing different from metal sintering?

Metals densify in the solid state — particles bond without going liquid. Borosilicate glass passes through a viscous-liquid range during firing, so it slumps under gravity and fuses with itself. Practical implication: support geometry matters more than for metal Filamets, and you cannot rely on a fixed shrinkage figure — the part reshapes during fusing.

Is the finished glass actually Pyrex®?

The finished part is borosilicate glass — the same chemistry family as Pyrex®. Pyrex® is a registered trademark of Corning, and we use the name to describe the chemistry, not to imply the brand. Functionally the finished part behaves like the borosilicate lab glassware you already know.

Can I anneal it the way a glassblower would?

Yes — a slow ramp down through the borosilicate annealing range (typically ~560–510°C with a hold) relieves residual stress just as it would for lampworked glass. If you skip the anneal you risk thermal-shock cracking later.

What kiln do I need?

Anything that can comfortably reach ~850°C with controllable ramp and hold. The TVF FireX is well-suited; a programmable glass-fusing or pottery kiln also works. You need ramp control to hit the annealing schedule properly — unprogrammed kilns are not recommended.

What else you’ll need

TVF FireX Sintering Kiln

Programmable ramp control gets you cleanly into the borosilicate fusing and annealing ranges.

Filawarmer

Strongly recommended for Glass Filamet™. Resets spool memory and reduces snap risk on this stiffer filament.

Glass Filamet™ Sample Pack

Not ready for a full spool? Try 100 g of Pyrex® Glass Filamet™ first to validate your nozzle, kiln and fusing schedule.

Made in South Central Wisconsin, USA. World-class technical support provided for all TVF products.

(TVF-FILAMET-PYREX-175)

SKU TVF-FILAMET-PYREX-175
Brand The Virtual Foundry
Shipping Weight 2.0000kg
Shipping Width 0.220m
Shipping Height 0.080m
Shipping Length 0.220m

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