Glazing – Technology and Surface Treatments

Warm Edge Spacers

Warm edge spacers are key components in double- or triple-glazed units, used to maintain the correct distance between panes. In addition to spacing, they serve several important functions:

• Accommodate stresses from thermal expansion and pressure changes

• Act as a moisture barrier to prevent condensation or fogging within the unit

• Maintain a gas-tight seal to preserve low-conductance gases inside the cavity

• Improve insulation and reduce interior edge condensation

Traditional spacers are made from highly conductive materials like aluminium. Warm edge spacers, by contrast, use materials such as vinyl (uPVC) or stainless steel, which offer better thermal performance. These spacers reduce heat loss around the glazing perimeter and are commonly specified in high-performance systems where thermal efficiency and condensation control are priorities.

Frit

Ceramic fritting is a common surface treatment applied to heat-treated glazing, allowing for patterns and colours to be integrated into the glass. A frit is a mix of finely ground glass, pigment, and a binder, which is applied to one surface of the glass and then fired in a tempering furnace to create a permanent, durable finish.

In double-glazed units, frit patterns are ideally placed on an interior surface within the sealed air space to protect them from wear. They can also be used in laminated glazing systems. Frits are often positioned on the interior face of the outer pane to reduce solar transmittance, and can be combined with low-emissivity (low-E) coatings.

The solar heat gain coefficient (SHGC) of fritted glass depends on the colour, pattern, and placement of the frit. While frits help reduce solar heat gain and control light transmission, they are not a substitute for external shading or advanced, spectrally selective glazing.

Acid-Etched and Sandblasted Glass

Both acid etching and sandblasting are surface treatments that give glazing a matte, diffused appearance.

• Acid Etching involves applying acid to the glass surface for a set time, which can be controlled to achieve various levels of diffusion. Masking techniques can create decorative patterns or images.

• Sandblasting uses high-pressure abrasive material to achieve a similar effect, though it may be less precise for intricate patterns.

Both methods scatter incoming light and obscure visibility through the glass, making them ideal for privacy or aesthetic applications. However, it’s worth noting that diffusion can increase perceived glare, as the matte surface reflects light more broadly.