Do you carry high-purity isostatic graphite?

Yes. We stock industrial and high-purity isostatic graphite for EDM, precision components, molds, and vacuum or controlled-atmosphere applications.

Is graphite suitable for blown-glass molds?

Yes. Isostatic graphite provides surface finish, thermal conductivity, and dimensional stability for molds, tongs, and float-glass fenders.

Why does hot glass not stick to graphite?

Because the glass melt does not wet the graphite surface, so no bond forms at the interface. That is why the mould can work without barrier coatings and the part comes out with a clean face.

Does the mould mark the part?

The glass finish reproduces that of the cavity, so the result depends on the grade and the machining. Fine-grain grades give more closed surfaces; the exact finish is defined on the drawing and validated on the first part.

How long does a graphite glass mould last?

It depends on the cycle, the contact temperature, and exposure to air during stoppages. There is no general figure, but covering the mould when the machine stops and avoiding abrupt cooling extends its use noticeably.

Can moulds be made from an existing glass part?

Yes. From the part or the drawing the cavity is captured, and grade and finish are proposed, accounting for draft angle and glass shrinkage on cooling.

Graphite mold in use during hot glassblowing

Glass applications

Blown-glass molds

They allow the formation of glass pieces through blowing processes.

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Glass forming mould

Also known as: Graphite moulds for glass · Glass blowing moulds · Hot glass forming moulds · Graphite moulds for art glass

[ Technical summary ]

In hot glass forming, the graphite mould receives the gob or the part at a temperature where glass still flows. The governing condition is that the surface must neither stick to nor mark the glass: graphite is not wetted by the glass melt and, by conducting heat, draws temperature from the contact face without chilling as abruptly as a metal mould. It is used in blown, pressed, and custom-formed glass.

[ Problem it solves ]

Shape hot glass without it sticking to the mould or being marked, in a contact where the mould surface directly defines the finish of the part.

Operating conditions

High temperature
Contact with molten metal or glass

When it is suitable

Glass is formed hot and touches the mould surface
The glass finish cannot show mould marks
The geometry is proprietary and machined to drawing or sample
Short runs or art pieces are produced

When it may not be suitable

The part is left in hot air during stoppages, with no protection
The mould takes impact or high clamping load on every cycle
The cycle cools the mould with water immediately after contact

Process challenges

Adhesion / sticking
Thermal shock
Surface wear

Advantages

Low adhesion
Thermal stability
Custom machining

Limitations

Wear from erosion and thermal shock
Possible metal contamination if the grade is unsuitable
Service life depends on cycles and metal flow

[ Critical selection variables ]

These variables define the grade and the geometry. Actual values are confirmed against the grade datasheet.

Operating temperatureDecisive
Glass compositionDecisive
Surface finish required on the partDecisive
Geometry and tolerancesDecisive
Heat-extraction rateRelevant
Thermal and duty cyclingRelevant
Thermal shock severityRelevant

[ Required material properties ]

Properties that guide selection. Numerical values come from each grade's datasheet.

Critical properties

Thermal shock resistance
Dimensional stability
Thermal conductivity
Non-wetting by molten metal

Secondary properties

Grain size
Machinability
Bulk density

[ Related ]

[ Frequently asked questions ]

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Technical content reviewed by ESGRAF — Last reviewed: September 8, 2026

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