Glass Nomenclature: A Common Language for Describing Glass

“Quarter-inch lami.” “Nine-sixteenths laminated.” “Three-eighths clear temp.” If you’ve ordered glass for any length of time, you know how much meaning gets packed into a few words, and how often those words get read differently. Terms vary from region to region, between imperial and metric, and even from one generation of glaziers to the next. When a description is vague, the wrong glass shows up and everyone loses time.

The National Glass Association (NGA) is working to fix that. Its technical paper Glass Nomenclature – Schema 1 (FB78-25), excerpted in Glass Magazine this summer, proposes a standard shorthand for describing glass makeups that anyone in the industry can read the same way. Here’s a quick guide.

The Basic Vocabulary

• Lite: a single panel of glass, or a single panel of laminated glass.
• Ply: one individual layer of glass or plastic within a laminate.
• Laminate: two or more plies bonded together with interlayer material.
• Interlayer: the bonding layer between plies. Besides holding the plies together, it can add performance such as penetration resistance, holding shards in place when the glass breaks, solar control, sound reduction, color or design.
• Insert: a sheet or other material sealed inside the laminate, whether or not it covers the whole lite.
• Kind: how the glass has been strengthened, written as a code: AN (annealed), HS (heat-strengthened), FT (fully tempered) or CS (chemically strengthened).

Why Metric?

The standard uses millimeters for glass, interlayer and airspace thicknesses. Metric numbers add up cleanly, so you can read the overall thickness of a makeup at a glance. If you think in fractions, here are the standard nominal equivalents for common flat glass thicknesses:

Writing a Single Lite

For a single (monolithic) lite, start with the nominal thickness in millimeters, then add the kind code. If there’s no kind code, the glass is assumed to be annealed.

• 6 = 6 mm (1/4″) annealed
• 10FT = 10 mm (3/8″) fully tempered, a common frameless shower thickness
• 12FT = 12 mm (1/2″) fully tempered

To call out the glass material, add a code in braces after the thickness and kind. No code means clear. Common codes include CL (clear), LI (low-iron), BR (bronze), GY (gray) and GN (green). So 10FT{LI} reads as 10 mm fully tempered low-iron glass.

Surfaces and Coatings

Every lite has an outboard and an inboard surface, and either one can carry a coating or finish. In the standard, a surface code placed before the thickness describes the outboard surface; placed after, it describes the inboard surface. Codes include * for a low-E or reflective coating, r for mirrored, a for acid-etched, f for fritted, d for digital print and p for painted or roll-coated. When a specific manufacturer’s coating is used, its name goes at the end of the code after a double asterisk (**).

Writing a Laminate

This is where the shorthand really earns its keep. List each glass ply from outboard to inboard, separated by commas. Then add a hyphen, the interlayer thickness in millimeters to two decimal places, and the interlayer code: b for PVB, ev for EVA, ip for ionomer or u for polyurethane.

• 3,3-0.76b = 3 mm annealed | 0.76 mm PVB | 3 mm annealed (6.76 mm overall, what many people call 1/4″ laminated)
• 3,3-0.38ev = 3 mm annealed | 0.38 mm EVA | 3 mm annealed
• 6FT,6FT-1.52b = 6 mm fully tempered | 1.52 mm PVB | 6 mm fully tempered

For laminates with more than two plies, list all the glass first. If every interlayer is the same, write it once: 6,6,6-1.52b. If they differ, list each interlayer in order: 6,6,6-1.52b,2.29b means 6 mm | 1.52 mm PVB | 6 mm | 2.29 mm PVB | 6 mm.

Why It Matters on Your Jobs

Compare “1/4-inch laminated” with 3,3-0.76b. The first leaves the ply thicknesses, strengthening and interlayer open to interpretation. The second leaves nothing to guess. That matters because:

• Interlayers change performance. Interlayer type and thickness affect safety, sound control and how the glass behaves when it breaks, which can matter for code compliance.
• Overall thickness has to fit. A laminate that comes in thicker than expected may not fit the glazing pocket or channel.
• Clear specs mean fewer remakes. When everyone reads the order the same way, you get the right glass the first time.

You don’t need to memorize every code to order glass. But the next time you write up a laminated or coated makeup, spelling out each ply, its kind and the interlayer removes the guesswork, whatever format you use. The full NGA paper, including every material, surface and interlayer code, is free to download.

Not sure how to spec it? Call us at (972) 506-9580 or send us a message.

Source: “Glass Nomenclature,” Glass Magazine, National Glass Association, July 2026, excerpted from NGA Glass Technical Paper FB78-25.