All three hide the bulb and soften the light, in different ways. Acid etching dissolves a thin layer of the surface and leaves a smooth satin matte; sandblasting roughens the surface with grit; opal glass is white through its whole body. We offer all three (SIGA, 2026). Choose acid etching for a smooth touch, sandblasting for a coarser texture, opal for an even white glow.
Acid-etched glass is glass whose surface has been treated with a hydrofluoric acid solution that removes a very thin layer and leaves a smooth, matte finish (Guardian Glass).
Sandblasted glass, or ground glass, is glass whose surface is roughened by abrasive grit to diffuse light.
Opal glass is glass that is white through its body, because particles or interfaces inside it scatter the light.
A frosted shade is one answer when a client wants a soft light without seeing the bulb. The word "frosted" covers several finishes, though, and they differ in touch, cleaning and the light they give. This guide compares the three we offer, so the drawing names the right one.
How does an acid-etched finish behave?
It is smooth to the touch and even in appearance. Guardian Glass describes acid etching as dipping the glass in a hydrofluoric acid solution that removes a very thin layer of the unprotected surface, creating a smooth, matte finish; it adds that the finish diffuses light evenly, reduces glare and is less prone to smudges (Guardian Glass). That description is for flat architectural glass; we apply acid frosting to blown shades as well (SIGA, 2026).
Choose it when the shade will be touched or wiped often, or when a fine, quiet texture suits the design. Unlit, an etched shade reads as a soft satin surface; lit, it glows evenly with the bulb hidden behind it. That evenness is the main reason to pick it over a blasted surface, whose texture you can see and feel. Ask for the etch to be confirmed on the sample, lit and unlit, before the batch starts.
How does a sandblasted finish behave?
It is rougher, and the grit decides the effect. An optics supplier explains that a coarser grit diffuses more and spreads light wider, while a finer grit transmits more light; it gives 120-grit and 220-grit as examples (Edmund Optics). Check on the sample how the surface handles fingerprints and cleaning, since a rough finish may show marks more readily than a smooth one.
Choose it when you want a visible, slightly coarse texture, and ask for the grit to be confirmed on the sample.
How is opal glass different?
Opal is a glass, not a surface finish, so the white does not depend on a coating and the whole wall diffuses the light. A lecture on commercial glass color explains that opal glasses get their white from light scattering at particles or interfaces inside the glass; when those are about the size of the wavelength of light or larger, the glass turns white and opaque (James E. Shelby, Lehigh IMI). For flat optical diffusers, the same optics supplier notes that its opal type, a milky coating on clear glass, diffuses light more efficiently than ground glass but loses more light to scattering (Edmund Optics); we would expect an opal shade to behave in a similar way, but that is an inference, so compare samples. Our glass pendant light shades page shows clear, white and textured pendants together.
Our molded shades are mainly made in clear and white glass (SIGA, 2026), and white molded shapes such as our white opal globe are opal glass.
| Acid-etched | Sandblasted | Opal glass | |
|---|---|---|---|
| Where the effect is | Surface | Surface | Whole body of the glass |
| Touch | Smooth satin | Rougher | Smooth |
| Fingerprints | Less prone (Guardian Glass) | May show more readily; check on the sample | Like clear glass |
How do I specify a frosted shade?
Name the finish (acid-etched, sandblasted or opal), and say whether it covers the outside, the inside or both. If the light level matters, ask for two samples, for example acid-etched clear and opal, and compare them lit with your bulb. We do not publish light transmission figures (SIGA, 2026), so the sample is the reference. The finishes and colors page lists our other surface treatments: screen printing, hot stamping, color spraying and plating (SIGA, 2026).
When is a frosted shade the wrong choice?
A frosted or opal shade is a poor fit when the design depends on seeing the bulb or on sparkle from a cut or ribbed surface, since diffusion softens both. It is also a poor fit when the maximum light output matters most, because diffusing glass loses some light to scattering. A clear shade with a frosted bulb can be the better route there.
Sources and Further Reading
- Guardian Glass: Acid-etched glass. A glass manufacturer's description of how acid etching is done and how the finish handles light and smudges. Checked 2026-10-18.
- Edmund Optics: ground glass and opal glass diffusers. Compares diffusion and transmission of ground (sandblasted) glass by grit and of opal glass. Checked 2026-10-17.
- James E. Shelby, Color in Commercial Glasses (Lehigh University IMI glass course, lecture 4). Explains how opal glasses scatter light. Checked 2026-10-18.
Frequently Asked Questions
Which frosted finish is easiest to keep clean?
Acid etching, in most cases. A glass manufacturer describes acid-etched glass as having a smooth surface that is less prone to smudges (Guardian Glass). A sandblasted surface is rougher and may show marks more readily, so check cleaning on the sample; opal glass has an ordinary smooth surface.
Which frosted finish lets the most light through?
Among sandblasted surfaces, a finer grit transmits more light than a coarser one, and, for flat optical diffusers, an opal coating loses more light to scattering than ground glass (Edmund Optics). We do not publish transmission figures, so compare two finishes on samples with your own bulb.
Is opal glass the same as frosted glass?
No. Frosting is a treatment of the surface, while opal glass is white throughout, because light scatters inside it (Shelby, Lehigh IMI). Opal hides the bulb well, so compare it with a frosted sample if the light level matters.
Unsure which finish suits your shade? Ask for samples in two finishes and compare them with your own bulb.
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