Arnold Glas – We know glass

Arnold Glas – We know glass

Despite its delicate, transparent appearance, glass is a strong and durable material. Nevertheless, when using glass there are a few things that need to be considered to both ensure the durability of the product and substantially reduce the effort involved in caring for it.


You can find out how our special glass material is manufactured and improve your knowledge of the technical terms used in the glass industry:

  • Manufacturing of glass

    The raw material mixture of silica sand, limestone and soda ash is melted at a temperature of 1,560°C. The hot glass mass is poured onto a bed of molten metal under controlled overflow conditions and flows into an endless glass ribbon. The speed of the ribbon and volume of glass flowing in determine its thickness. The glass ribbon is then transferred to a cooling channel and at the same time cooled down uniformly to room temperature. Finally, it is cut into standard dimensions (float glass 3,210 x 6,000 mm) and stacked.



  • Absorption
    The portion of total incident radiation that is absorbed by the glass and subsequently re-radiated Normal, clear glass absorbs less radiation than tinted glass. Additional coatings can absorb more or less solar radiation depending on the composition of the coating.

    In insulated glass (double glazing), the stainless steel or aluminium profile that keeps the glass panes at the required distance from one another.

    A disruptive effect in single pane safety glass (toughened glass). The thermal tempering or toughening process introduces different mechanical stresses into the glass that cause double refraction. These double refractions, also known as anisotropies, are perceived as disruptive optical effects in polarised light. Polarised light is contained in normal daylight. Arnold Glas has developed a method for reducing anisotropy in such a way that it is no longer visible to the human eye.

    Thermally insulating and sun protection glazing needs a coating to achieve certain structural characteristics and reduce the emissivity of the glass surface. A distinction is made between soft and hard coatings. Soft coatings are applied downstream of the float process using what is known as the magnetron sputtering process. Hard coatings, on the other hand, are applied during the float process.

    Bending strength
    When glazing is bent, one side is compressed and the other elongated. The high strength is based on a compressive stress on the surfaces and tensile stress in the core.

    CE marking
    The new EU directives prescribe the application of the CE marking. The CE marking indicates conformity with EU directives, not with standards, so it has the status of an administrative mark, not a test mark.

    Heat radiation is the main cause of heat loss from glass, depending on the emissivity of the glass surface. The emission is around Ɛ = 0.85 for uncoated glass. Or to put it simply: 85% of the heat absorbed by the glass is emitted at the glass surface.

    Float glass
    Float glass is basic flat, transparent and uncoated glass. Variations of normal float glass include batch-tinted glass (green, grey, bronze) and clear glass with low iron oxide content (low iron glass).

    The term g-value is an abbreviation for
    total solar energy transmittance The g-value is the sum of the direct transmission of solar radiation plus the inward emission of heat through radiation and convection. Uncoated glass has a g-value of around 0.85 or 85%.

    Heat Soak Test
    The heat soak test is a process used on single pane toughened safety glass to prevent spontaneous breakages. In this hot air test, the thermally toughened glass is exposed to a temperature of 290°C for several hours in a special heat soak oven. The test process is documented. The heat soak test is mandatory, for example, for anti-fall glazing and facade panels made from single-pane toughened safety glass.


  • Light permeability / Light transmission
    The light transmission (LT value) describes the percentage of solar radiation in the visible light range (380 to 780 nm). The LT value is dependent on the composition of the glass mixture, the glass thickness, and the coatings applied.

    Low E glass
    To minimise energy losses, low E glass is used as standard these days. Low E is an abbreviation for low-emissivity (low thermal radiation) and describes an insulating glass to which an ultra-thin layer of metallic oxide of around 100 nm has been applied. This layer reduces emissivity and serves as a heat and/or sun protection layer.

    PVB film
    PVB is the abbreviation for polyvinyl butyral. The material is used as a visco-elastic interlayer (0.38 mm) in laminated safety glass. Several interlayers can be used to increase the residual load-bearing capacity.

    Edge seal
    The edge seal is a component of insulated glazing and designates the elements that join the glass panes in the edge area using a special spacer bar (aluminium, stainless steel or plastic) and adhesive and sealing compounds.

    A desiccant is used in the hollow spacer bars in the edge seal of insulating glass to absorb any dampness resulting from condensate. This is why the spacer bars have small perforations in them.

    This is the heat transmission coefficient of a material. It indicates how much heat is flowing in the case of a temperature difference of 1 K (Kelvin) between warm and cold. For example, in the case of an outside temperature of -10°C and inside temperature of 20°C the difference is 30 K. The current U-values are around 2.0 W/m²K to 0.7 W/m²K.

    The small g indicates that the U-value applies only to the glazing. The Ug-value of insulating glass depends on the thermally insulating coating, the type of gas filling, the gas filling level and gap between the panes.

    (Ü-mark, German quality certification mark for building products)
    In Germany, designates building products that comply with the relevant technical regulations, building inspectorate approval, building inspectorate test certification or special building approval provisions.