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What Shade Glasses for Borosilicate: Boro Torch Eyewear Explained

What shade glasses for borosilicate lampworking: what shade numbers mean, the 2, 3 and 5 boro lenses makers sell, when to go darker, and why didymium isn't enough.

By Joe Blanchard, sixteen years on the distribution side of the glass industry · Updated

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Short answer: There is no single shade number for all borosilicate work, and the eyewear makers say so by selling several. Phillips Safety, which makes lampworking lenses, sells boro lenses rated as the equivalent of a welding shade 2, 3 or 5: it positions shade 2 for soft glass and small boro, shade 3 for smaller boro work and shade 5 for larger boro work. The darker the lens, the more infrared and visible light it holds back, so the shade climbs with the size of the piece, the size of the flame and the length of the session. Whatever the number, a boro lens also has to deal with the sodium flare, which a plain green welding lens does not do well, and a lens sold only as didymium is not boro eyewear: Phillips’s own boro guidance calls for sodium-flare, UV and infrared protection together, and the word “didymium” does not tell you a lens has the infrared part. Start from the lens maker’s recommendation for your work; their instructions take precedence over any guide.

The background on what didymium does and does not do is in our didymium glasses for lampworking guide. This article is about the number.

What a shade number means

Shade numbers come from welding, and the scale is simple: the higher the number, the darker the filter and the less light reaches your eye. OSHA’s eye and face protection standard frames filter lenses as protection from injurious light radiation, not just glare, which is why a shade rating is the language boro eyewear is sold in.

OSHA’s shade guidance was written for welding, cutting, brazing and soldering, not for lampworking, so there is no row in it for “boro marbles”. One line in it does describe our problem exactly: in oxyfuel gas work where the torch produces a high yellow light, OSHA says it is desirable to use a filter lens that absorbs the yellow or sodium line. That is the sodium flare, and it is why boro eyewear for flameworkers combines a shade rating with sodium-flare filtering instead of simply borrowing a welding lens.

Why boro needs a shade and soft glass often does not

Borosilicate is worked at higher temperatures than soft glass and usually in larger masses, so it radiates much more infrared. Infrared is invisible and does its damage slowly; the old name for the result is glassblower’s cataract. A Swedish epidemiological study of glass workers with twenty or more years of infrared exposure, indexed on PubMed, found significantly more cataract in the oldest exposed workers than in unexposed controls. Those were furnace workers, a heavier exposure than a bench torch, but the direction is the same: more hot glass, for longer, means more infrared.

Didymium and its refined cousin ACE (Phillips 202) are sodium-flare filters first. Neither name is a protection specification: whether a given lens also blocks UV or infrared depends on that exact lens, and Phillips’s own pages are not consistent about didymium and infrared. For boro, Phillips’s answer is a lens specified for UV, infrared and sodium flare together, which is why it sells the boro lenses below rather than recommending plain didymium. The comparison between those two lens families is in didymium vs ACE glasses.

The shades makers actually sell for boro

These are Phillips Safety’s own boro lenses and the work the company positions each one for. The shade figures are the maker’s stated welding-shade equivalents.

LensMaker’s stated equivalentWhat Phillips positions it for
BoroTruView 2.0Welding shade 2.0 (UV and IR)Soft glass, small borosilicate pieces, kiln and furnace work
BoroView 3.0 / BoroTruView 3.0Welding shade 3.0Smaller borosilicate work
BoroView 5.0 / BoroTruView 5.0Welding shade 5.0Larger borosilicate work

All of them also filter the sodium flare, which is the difference between a boro lampworking lens and a plain welding lens. Phillips describes its BoroTruView 3.0 as formulated for color recognition with a color-neutral infrared filter, which matters if you work colored boro and need to read the color while it is hot, and it offers a mirror coating on the BoroTruView 3.0 that it says reflects infrared and reduces eye strain.

Editor’s note: the low end is where guidance disagrees, even inside one maker. Phillips positions its shade 2.0 lens for small borosilicate pieces, while its own boro support answer names only the 3.0 and 5.0 lenses for borosilicate work. We cannot resolve that for you: the right answer depends on the size of your work, your torch and your hours. If you are between two shades for boro, ask the lens maker, and when in doubt take the darker one that still lets you see the work.

How to pick between shade 3 and shade 5

Phillips’s split between the two is small work versus large work. In practice, these are the things that push you toward the darker lens:

  • Size of the glowing mass. A pendant or a small marble is a small source. A large marble, a thick-walled vessel, heavy solid sculpture or big tubing is a large one, and it radiates for the whole time it is hot. Our sculpting solid boro basics guide covers why solid work is its own exposure.
  • Size of the flame. A bigger torch heats more glass faster and makes more light. If you are moving up to a larger burner, as covered in the best torch for borosilicate guide, revisit the eyewear at the same time.
  • Session length. Infrared exposure is cumulative. A full day at the torch is a different exposure from a half hour.
  • Clear versus color. Makers describe their color-recognition lenses separately because a darker lens makes color harder to judge. That is a reason to choose a lens formulated for color, not a reason to go lighter than your work calls for.

The welding convention OSHA describes is to start with a shade too dark to see the work and step lighter until you can see well, without going below the minimum for the job. The same logic works at the torch: the minimum comes from the lens maker for your glass and scale, and comfort decides whether you sit at it or above it.

Split lenses: two shades in one frame

Many boro workers do not want to look at the whole room through a shade 5. Phillips’s split-lens lampworking glasses solve that with a base lens for looking around the bench and a darker infrared segment across the bottom two thirds of the lens for looking down into the flame. The maker’s split-lens page (read 2026-09-28) offers an upper lens of Sodium Flare Poly or BoroTruView 3.0 over a lower infrared-shaded segment of 3.0, 4.0, 5.0, 6.0 or 8.0.

The design assumes you look down into your work. Check that the darker segment covers your line of sight at your normal working posture before you rely on it.

Layering a welding shade over didymium

If you already own didymium or ACE glasses and work boro only some of the time, a green welding-shade clip-on over your flare filter is the other route: the rose lens removes the flare, and the green clip-on adds rated infrared filtering that the flare lens may not have. The trade-off is bulk and two lenses to keep clean, and the combination has to be rated for what you are doing. Prescription wearers have their own version of this problem, covered in didymium over prescription glasses.

What does not work is the reverse shortcut: welding glasses on their own. Phillips’s comparison of didymium and welding glasses says plainly that welding glasses are unsuitable for lampworking because they do not deal with the sodium flare properly. You end up with a dark scene and the flare still washing out the work.

Beyond boro: quartz goes darker

Quartz is worked hotter again, and Phillips treats it as a separate lens problem. Its quartz glasses use a split lens with a lighter upper lens and a dark green welding-shade lower lens; the company lists green shade 6.0 or 8.0 for the lower segment. If you are moving from boro toward quartz, do not carry your boro shade across. The torch side is in best torch for quartz.

A quick checklist

  • Glass: boro needs flare filtering plus UV and infrared filtering; a lens sold only as didymium is not enough, and the family name is never the specification.
  • Shade: the maker’s range for boro lenses is 2 to 5; small work at the low end, large work at 5.
  • Disagreement: guidance on whether shade 2 is enough for small boro varies; ask the lens maker, and lean darker when unsure.
  • Rating: confirm the exact lens is rated for your work, and for impact under ANSI/ISEA Z87.1 if your studio or school requires it.
  • Fit: side coverage and a frame that does not slide matter as much as the number, and your posture decides where you look through the lens (ergonomics at the torch).
  • Precedence: the eyewear maker’s instructions override this guide.

Sources

Editor’s note: shade equivalents and split-lens combinations reflect Phillips Safety’s own pages as found during our research in September 2026; the maker’s site could not be loaded directly from our research environment, and product lines change, so confirm the current rating of any lens with the manufacturer before you buy. Shade requirements vary with the glass, the size of the work, the torch and local workplace rules.

About the author

Written and edited by Joe Blanchard, who spent 2007 to 2023 on the distribution side of the glass industry in Asheville, North Carolina. GlassTorches.com is his independent, manufacturer-first buyer's guide. More about the editor.

How this guide was sourced: figures come from the manufacturer's own pages and manuals where we have them and are labelled as estimates where they are ours; the catalog on this site is the source of truth, and where sources disagree the guide says so. Confirm the current spec with the maker before you buy. How we work.