Heat Treated & Caramelised

Weaving lubricants or ‘sizings’ can be removed by heating, these textiles then have extremely low levels of outgassing in final applications – can be critical for some industries.

Caramelised Glass Cloth

Caramelised glass cloth is made from standard woven glass fibre, and has undergone an additional finishing stage where the cloth is run through a high temperature oven.  This process burns off the small fraction of weaving oils and lubricants (sizing) that are present on standard glass fibre yarns. Please see the FAQ’s page on fuming and thermal degradation for more information. The process can also help in the removal of surface fibre and fly, which can help reduce irritation when handling.

This heating results in the tan or ‘caramel’ colour of the fabric. ‘Heat treated’ and ‘heat cleaned’ are other names for similarly processed materials.

Caramelised glass cloth is often specified where there can be no fumes or ‘off gassing’ during the first heat cycle of the end product, or in some applications where the weaving oils and lubricants can interfere with adhesion levels to other products.

The most common caramelised fabrics are listed below, but please feel free to contact us if you have an exact specification or construction in mind, any loomstate fabric, continuous filament or texturised can be heat treated or caramelised.

Weight (g/m2)	Weave Pattern	Type	Common widths (mm)
200	Plain	Continuous filament	660, 1270
400/420	Satin	Continuous filament	1000
600	Plain	Texturised	1000, 1200, 1500, 2000
780	Plain	Texturised	1000, 2000
950	Crowfoot Satin	Texturised	1000, 1500
1000	Plain	Texturised	1000, 1500

FAQs

What is Caramelised Glass Cloth?

Heat treated glass cloth is standard woven glass fibre that has been passed through a high-temperature oven. This burns off the weaving oils and lubricants, known as sizing, present on standard glass fibre yarns. The heating produces the fabric’s characteristic tan or caramel colour. It is also referred to as heat treated or heat cleaned glass cloth.

Why Does Glass Cloth Fume or Smoke on First Use?

Standard glass fibre yarns contain a small amount of weaving oils and lubricants applied during manufacture. When first exposed to heat these burn off, producing fumes during the first heat cycle. Heat treated glass cloth eliminates this by burning off the sizing during manufacture.

When Should I Use Heat Treated Glass Cloth Instead of Standard Glass Cloth?

Heat treated glass cloth should be specified where fumes or off gassing during first use are not acceptable, or where weaving oils could interfere with adhesion in downstream bonding or coating processes.

Does Heat Treatment Affect the Performance of Glass Cloth?

Heat treatment does not negatively affect the thermal or insulation performance of the fabric. The process can also help reduce loose surface fibres, which may reduce skin irritation when handling.