Glazing Materials

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GLAZING MATERIALS: GLASS

Architectural glass - glazing for windows, doors, shower enclosures and other household - installations is governed by the Consumer Product Safety Commission's (CPSC) Safety Standard for Architectural Glazing Materials.

The standard, whose purpose is to reduce or eliminate risk of injury associated with walking, running or falling through or against glazing materials, specifies the following locations as "hazardous":

1. Storm doors
2. Interior and exterior doors
3. Shower and bathtub doors and enclosures
4. Certain glazed panels (in "hazardous" locations)
5. Sliding or patio-type doors

All glazing materials manufactured for use in these locations must comply with the safety standard and must be tested and certified by the manufacturer as conforming to the standard.

Common safety glazing materials include:

Tempered glass - crumbles into small pieces if broken; leaves no jagged or sharp edges; must be ordered to size.

Laminated glass - plastic that is bonded between two sheets of standard glass; plastic sheet retards shattering; finished thickness is 1/4", which may be too thick for most household replacement situations.

Wire-reinforced glass - wire mesh embedded in standard glass reduces the chances of shattering; also 1/4" thick. This product does not meet CPSC requirements for approved safety glazing, and cannot be sold for use in the specified hazardous locations. It is, however, exempted from the CPSC requirements for use in fire-retardant applications.

Standard glass can be sold for purposes not covered by the safety standard. It comes in three grades: AA for highest-grade work; A for superior glazing quality, and B for general purposes. A non-reflective glass can be sold for decorative framing.

Approved rigid plastics, including acrylic and polycarbonate-easy to handle, can be cut to size; less susceptible to breakage than glass products; will fall into large pieces with curved edges if it does break; may scratch easily.

Scratches in plastics can be removed by buffing with automotive paste wax containing no rubbing compound and can be minimized if cleaned with plastic cleaner and polish products.

Acrylic safety glazing is commonly used to replace broken glass in windows and doors. Acrylic plastic sheets are manufactured in widths from 18" to 48" and lengths up to 96".

When replacing single-strength glass with acrylic safety glazing, recommend .100" sheet thickness; when replacing double-strength glass, recommend .125" thickness.

Composition Glass - Composition glass is imbedded with a transparent layer of metal oxide particles; it cuts heating and cooling costs. The metal layer causes the glass to release heat half as fast as conventional glass, thus keeping more heat in during the winter and out during the summer. Composition glass is used mostly in double-paned windows; it usually increases the cost of the windows.

Cutting Tools

Handheld glass cutters for use on standard (non-safety) glass have an alloy steel wheel at one end to score the glass, and a ball knob or notched second end to break the glass along the score line. A table model with rotating base cuts circles as well as straight cuts.

Similar tools are used for cutting laminated and wire-reinforced safety glass. However, laminated glass, often used in shower doors, should be cut with a wheel no larger than .170". A larger wheel will roll over the "valleys" in the pattern usually found on laminated glass and not give a continuous score. In addition, the glass must be scored on both sides since it is actually two pieces of glass. The scores must align perfectly.

Wire-reinforced safety glass needs a score only on one side but after breaking, the wire mesh must be cut just as the plastic sheet must be cut on laminated glass.

Other glass-cutting tools include glass cutters with interchangeable cutting wheels so that glass of various thicknesses and textures can be cut; cutting machines designed for cutting ceramic tiles; and glass cutters that dispense a fine bead of oil to ease glass scoring. There are also point drivers especially designed for picture framing and other glazing needs. Special glass pliers help grip the glass for clean breaks.

Rigid plastics can be easily cut with special plastic-cutting tools available from a number of manufacturers.

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Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.