Tempered glass cannot be cut or processed after tempering. During thermal tempering, an extremely strong unified stress zone is created throughout the glass. If this stress is released from any point, the entire glass crumbles into small crumbs. This described crumbling is a safety feature. Therefore, all cutting, grinding, holes, and other processing must be done before glass tempering.

Tempered glass withstands frost excellently. Outdoors, however, it should be noted that if meltwater gets into the glazing structure, which freezes at night for example, the ice expanding may squeeze the glass and break it. The glazing structure should be designed so that water does not enter the structure and the structure is ventilated.

Tempered glass withstands heat and thermal shocks significantly better than non-tempered glass. The temperature difference inside tempered glass may be maximum 200 degrees, and the maximum operating temperature is +300 Celsius. Heat-resistant glass and Borosilicate glass (Borofloat) withstand heat even better.

Tempering is mandatory primarily when building regulations require it, or when broken glass could pose a personal safety risk – regular glass breaks into large, sharp shards that can cause serious cuts. Mandatory or highly recommended applications include: hearth glass (always tempered due to hot coals), sauna glass walls (temperature fluctuations), glass doors and low-positioned glazing (collision risk), and all-glass tables (full weight on glass). Handrail glass is always tempered and laminated to ensure safety. Terrace roof glass is often also tempered and laminated, especially for longer spans.

Tempered glass does not actually break more easily from the corner than normal glass – the difference is what happens when it breaks. When a normal glass corner receives an impact, typically only a small piece breaks off. The safety feature of tempered glass works so that if the stress structure is released from any point – including the corner – the entire glass shatters at once into small, blunt pieces. This is an intentional safety feature that prevents dangerous sharp shards from forming.

Normal clear glass contains iron, which gives the glass a greenish tint, especially in thick glass and at the glass edge. Extra clear glass (optiwhite, clearvision) is made from raw materials with very little iron, so the glass is significantly clearer and color reproduction is purer. The difference is especially visible in white or light back-painted glass: normal glass appears strongly green, while extra clear glass keeps the color almost pure. Extra clear glass is recommended for all interior glass, mirrors, and back-painted glass.

Yes, but significantly less than normal glass. Very small glass pieces (e.g. narrow 50-100mm wide glass shelves) may appear almost crystal clear at the edges, but in slightly larger pieces (e.g. 200mm wide glass shelf), even extra clear glass edge starts to appear green or dark green. Edge green depends on glass thickness, viewing angle, ambient lighting, and edge grinding type.

No, it is not completely colorless, but the difference to normal glass is still significant. Extra clear glass still contains some iron, although much less than normal glass. In thin glass (3-6mm) the difference to normal glass is clear but not dramatic. In thick glass (10-19mm) even extra clear glass starts to appear slightly greenish, although much less than normal glass. If you need absolutely colorless glass, we can deliver chemically purified borosilicate glass as a special solution.

Polished edge means that the glass edge is ground flat at a 90-degree angle and polished clear. The edge looks neat and finished. Beveled edge means that a slanted grinding (usually 10-20mm wide) is made on the glass surface edge area, which brings a classic, luxurious look to the glass and reflects light beautifully. Bevel is usually ground at about 3-7 degree angles. There is also 45-degree bevel, which is steeper and more modern. Polished edge is functional, beveled edge is more an aesthetic choice.

Yes, absolutely. In table glass, the edges are visible and often touched by hand. Without edge polishing, glass edges are sharp and can cause cuts. We always recommend at least polished edge for table glass. If you want to add appearance, you can also choose beveled edge, which brings a luxurious look to table glass. Edge polishing also slightly increases the glass bending strength.

You can wash the front side (non-painted side) of the glass normally with glass cleaner. The back side (painted side) does not withstand washing or scrubbing, and must always be protected against another surface (wall, table surface). Never use abrasive cleaners or rough cloths on back-painted glass, even on the front side, as they may scratch the glass. Microfiber cloth and glass cleaner are the best options. Back-painted glass is intended for indoor use and the painted surface is always protected.

Painting is always done on the back side of the glass. When you install the glass on a wall, for example, the painted side is against the wall and the front side of the glass faces the viewer. This way the painted surface is protected from scratches and wear. When you look at the glass from the front, you see the paint color through the glass. This is why we recommend extra clear glass as a base - it distorts the color less than normal glass. In our calculator, when designing back-painted glass, the dimension drawing shows the unpainted front surface of the glass, the painting is on the back.

No. Tempered glass cannot be processed in any way after tempering - not drilled, cut, ground, or milled. During the tempering process, an extremely strong stress structure is created in the glass, and if even the smallest flaw is made to it (e.g. drilling a hole), the entire stress is released and the glass explodes into small pieces. All processing - holes, cuts, grindings, millings - must be done BEFORE tempering. It is extremely important to carefully plan all necessary holes and processing during the ordering phase.

Yes, absolutely. Hearth glass must always be tempered into safety glass. Reasons for this: 1) People have to walk on the glass (load-bearing capacity and safety), 2) Hot coals or firewood can drop on the glass (thermal shocks), 3) Metal tools such as fireplace poker can fall on the glass (impacts), 4) When broken, tempered glass shatters into small safe pieces and does not cause cuts. Hearth glass is usually 6mm, 8mm or 10mm tempered glass. Note: hearth glass is NOT the same as fireplace door glass - tempered glass must never be used as a fireplace door glass, which is exposed to direct flame (+700 °C). A fireplace door requires fire-resistant ceramic glass.

Absolutely not! Tempered glass must never be used as a fireplace door glass. The fireplace door glass is exposed to direct flame and temperatures that can exceed +700 °C. The maximum operating temperature of tempered glass is +300 °C, so it will break in a fireplace door. Fireplace door glass must be fire-resistant ceramic glass (e.g. Robax or Neoceram), which is designed to withstand direct flame and extremely high temperatures. This is a safety issue - using the wrong glass type can cause a serious fire or personal injury.

Yes, but the beveled edge must be done BEFORE tempering. Tempered glass cannot be processed after tempering. When ordering, you select both tempering and beveled edge, and we process the glass in the correct order: first the bevel is ground, then the glass is tempered. Note that the beveled area usually does not fully temper because the glass thickness changes in the bevel. Bevel-edged tempered glass is an excellent choice for example for hearth glass, which requires both safety (tempering) and a luxurious appearance (bevel).

Fine edge polishing is a matte-finish edge grinding where the glass edge is ground smooth but not polished to clear. The edge appears matte and slightly lighter than when polished. Fine edge polishing is often used: 1) When a matte aesthetic look is desired, 2) When the glass edge is not fully visible but still needs finishing, 3) When you want to reduce edge green tint (matte surface reflects less).

Yes, slightly. Glass "shades" or darkens and slightly changes the paint color. The thicker the glass, the more the color changes. Normal glass gives a strong greenish tint, especially to white and light colors. Extra clear glass (optiwhite) significantly reduces this effect but does not eliminate it completely. Black color hardly changes, dark colors change only slightly, but light and bright colors can change noticeably.

Back-painting withstands normal indoor humidity well, but the painted surface must not be in constant contact with water. This is why the painted side must always be installed against a solid surface (wall, table surface). Back-painted glass can be used as kitchen splashback glass and bathroom wall glass, as long as the painted side is protected against the wall. Do not use back-painted glass outdoors or in applications where the painted surface comes into direct contact with water. Upon request, it is also possible to powder coat the glass back, which makes the coating very hard and suitable for outdoor use.

Yes, they can, but only partially. Holes can overlap by at least 1/3, creating a longer opening. For example, if two 40mm holes are drilled partially overlapping, you can get an approximately 60mm long opening. This is useful for cable pass-throughs or other special shapes. The hole edges may be processed straight if the production method requires it. Note that partially overlapping holes weaken the glass strength in that area, so such glass is always recommended to be tempered. Upon request, we can also machine various shaped openings and millings with CNC.