Frequently Asked Questions

Frequently Asked Questions

1 How available are your products? (lead-times?)

Pilkington's products are readily available through our fabrication customer base. Since our coated products are pyrolytically coated, they are typically an inventoried product and can be fabricated, heat treated, etc. at any time.

2 How can I best minimize glazing costs no matter what glass is selected?

Float glass is produced in a continuous ribbon process with a standard width of 130" in North America factories. Therefore, most standard shipping sizes include one dimension of 130". If you design your projects with awareness that maximizing the ribbon width (130") results in greater utilization of production, higher optimization can be realized and is usually figured into the cost to produce the final product. For example, a design requiring 60" in glass width will result in two pieces of glass across the ribbon or 120" in total - a 92% yield of the 130" dimension. A size that requires 69" in glass width may result in a single piece of glass from the 130" dimension - a 53% yield of the 130" dimension. The better the yield the lower the cost and the better chance for you to maximize your return on glass investment.

3 How do I get samples of your glass products?

You can obtain samples of Pilkington products by contact us at

4 How do I handle glare issues?

Glare has a direct correlation to visible light transmittance. Lower visible light transmittance results in less glare. One of our most effective products to control glare is Pilkington SuperGrey™ High-Performance Tinted Float Glass.

5 How does Low-E glass work?

Heat energy is comprised of long and short wave radiation. Low-emissivity coatings help reflect the long wave heat energy back towards its source. The primary purpose of Low-E glass is to improve the insulating value (u-value). For more detailed information on Pilkington Energy Advantage™ Low-E Glass, click here.

ATS Bulletin #135 - "Handling, Inspecting, and fabricating Pilkington Low-E Glass

ATS Bulletin #138 - "How Low-E Works"

6 How much does your glass cost?

Pilkington is a primary float glass manufacturer. We supply our glass in a non-fabricated, non-assembled form to our customer base, who then perform any fabrication of the glass as required (cutting of glass to the proper size, heating treating, insulating glass, or laminating). We would recommend contacting a local glazing contractor to assist you with any budget information.

7 On which surface do you recommend applying the low-e coating?

Pilkington Solar-E™ Solar Control Low-E and Pilkington Eclipse Advantage™ Solar Control Reflective Low-E are coated with pyrolytic low-e coatings, on a unique range of tinted glasses. These products should be glazed with the coating on the #2 or #3 surface. Typical usage is a #2 surface application which allows the base color to be more apparent and provides more subtle reflectivity.

The Pilkington Energy Advantage™ Low-E Glass provides high thermal insulation and passive solar heat gain. The coating can be applied to the #2, #3, or the #4 surface. For enhanced thermal performance, use Pilkington Energy Advantage

ATS 176 Handling, Inspecting, Fabricating and Installing Pilkington Eclipse Advantage™ Solar Control Reflective Low-E Glass.

ATS 190 Handling, Inspecting, Fabricating and Installing Pilkington Solar-E™ on Tints Solar Control Low-E Glass

ATS 137-4 Improvements in the Appearance of Installed Pilkington Energy Advantage™ Low-E Glass

8 What is a shading coefficient (SC) and how does it compare to the solar heat gain coefficient (SHGC)? Does a lower shading coefficient mean less visible light?

Glazing that blocks greater levels of solar energy have lower shading coefficients. The shading coefficient is the ratio of solar heat gain admitted through the glass as compared to the solar heat gain admitted through 1/8" clear glass (1/8" clear glass = 1.0 Shading Coefficient). The SHGC is similar to the SC, but also accounts for absorbed, convected, and inwardly radiated solar energy. The SHGC can be calculated by multiplying the SC x .86 (SHGC=SC*0.86). Both the SC and the SHGC are values which represent the solar heat gain through the glazing from the total solar energy spectrum. They do not necessarily have a direct correlation to visible light transmittance. A good example of this is Pilkington EverGreen™ High-Performance Tinted Float Glass, which allows for a higher visible light transmittance and, at the same time, a lower SC than a typical bronze or grey tinted glass.

9 What is the difference between a hard coat and a soft coat?

A hard coat is a pyrolytic coating applied on-line during the initial glass manufacturing process. Since the coating is applied while the glass is in the semi-molten state, it becomes part of the glass surface. A soft coat is a sputtered process that is applied in a batch method after the initial glass manufacturing. The sputter coating is not integral to the glass surface, but rather is a surface coating. There are advantages and disadvantages to both coating options. Please contact Pilkington Product Specialist for more information. For more information on pyrolytic coatings.

10 What is the difference between heat strengthened (HS) and fully tempered (FT) glass? How do I determine which is needed for my project requirements?

Both processes increase the strength of glass (FT is 3 times as strong as annealed glass of the same thickness and configuration; HS is twice as strong as annealed glass of the same thickness and configuration). NOTE: Heat treating of glass does NOT change the stiffness of the glass and amount of deflection under load as compared to annealed glass. Heat treating of glass is commonly classified in 2 types (FT=Fully Tempered, and HS=Heat Strengthened): FT is more commonly used in safety glazing applications since its breakage pattern results in innumerable small fragments of more or less cubicle-shaped pieces of glass which may vacate the opening (Please check local code requirements for approval to use FT glass as a safety glazing material.). HS glass is used in areas where FT breakage patterns would not be desirable, for example, spandrel applications. HS glass has a breakage pattern similar to standard annealed glass. Either of these methods is typically sufficient to address particular thermal stress concerns although, on rare occasions, even tempered glass can break spontaneously, without any applied load, due to small inclusions that may be present in all float glasses. For additional information, please reference Pilkington Architectural Technical Services bulletins.

11 What is the standard specification for flat glass? Can you assist me with writing a glass specification? How do I know which performance numbers are the most critical for my project?

The standard specification for flat glass is ASTM C-1036, and we know it can be somewhat complex and confusing. That's why we developed the Pilkington Sun Management Calculator. This program will automatically calculate the performance data for the most common glazing combinations, glazed monolithically, or in an I.G. unit. Then, when you've found the combination that best meets your aesthetic and performance requirements, the program will generate an outline specification.

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