Filter eyewear: glass or plastic?

Occasionally the question of ‘Glass or Plastic’ comes up in an e-mail, and I always advise the questioner that plastic (or polycarbonate) lenses are not a good choice for the glass working studio.

The reasons for this vary, but boil down to a couple of main issues:

1) Durability. Plastic/polycarbonate lenses WILL scratch, regardless of any supposed anti-scratch coatings. Let’s face it, the glass studio is about the worst place to wear plastic/polycarbonate lenses if you want to avoid scratches. Glass chips and dust are everywhere even if you are the cleanest glassworker in the world. All it takes is one small scratch (and it always seems to be dead square in the center of the lens!) .

2) Filtration issues. Despite the high-tech ability of plastic manufacturers, no one has been able to invent a dye that exactly replicates the multi-notch filter that didymium and ACE/AUR-92 provide. Let’s be clear (sorry, pun not intended): the notch filter at 575-590 nanometers is an absolute requirement to filter out sodium flare. This notch needs to be sharp and well-defined. If the notch at that point is too wide, you remove the surrounding wavelengths of light, which, of course, removes your ability to see those colors, which affects your color perception.

3) Fading issues. ALL plastic/polycarbonate dyed lenses fade. The manufacturer may claim that they won’t — but under what conditions are they making those claims? In a medical office or surgical suite? In an industrial setting? Have they tested the dye in front of a 2800 degree F torch for 8 hours per day, 6 days a week for a month? Most likely not. All of the dyed lenses that I have ever seen fade over time and exposure to torch light/heat, something that these lenses were NEVER designed for.

Plastic or polycarbonate lenses are inexpensive, and you get exactly what you pay for. You will have to replace them frequently as they get scratched and faded. Perhaps as often as every 4 months, depending on how much time you spend behind the torch. A good pair of glass lenses will last literally for years. An average pair of plastic so-called “borosilicate glassworker” filters cost $60.00. An average pair of glass full-coverage borosilicate glassworker filters cost $ 135.00. If you (conservatively) replace your plastic filters every 9 months due to scratching/fading, you will have paid for a pair of glass filters in 18 months, and the glass lenses highly resist scratching and absolutely will not fade.

The average pair of glass borosilicate glassworker filters will last (if you take good care of them) many years. Plastic/polycarbonate filters will last maybe as long as 9 months.

And, as an added bonus, you don’t require a separate add-on lens holder if you require a prescription. Glass lenses quite easily can have your prescription ground into the filter. Plastic/polycarbonate filters cannot.

The choice is always yours, and the best choice is the one that is made with all the information available.

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4 thoughts on “Filter eyewear: glass or plastic?

  1. I am a lampworking instructor and i constantly get questioned about tools and supplies from my students… lately as more and more of these cheap polycarbonate glasses are appearing my students have been asking me about them… i always tell them that they dont seem like a good idea… but now you have armed me with new information… and i thank you for that… i was wondering if you would mind if i printed this post as a handout for my classes during my “safety in the studio” lectures…

  2. I came across your blog and was hoping you could lend me some wisdom. I am a safety professional, but I know little to nothing about lampwork bead making. One of our professors (I work at a university) wants to do a lab activity in which students make their own glass beads. The question is about what sort of eye protection they should wear? I have seen plenty of specialized eyewear for sale that is prohibitively expensive for only 30minutes of use. Do you know of any eye protection that would be affordable for short time student use and yet give the impact/UV/IR protection necessary?
    I would sure appreciate any advice you would send my way.
    Thanks, Joy

    • Joy, though I am loathe to recommend it, if they are only going to be working one time for 30 minutes, then standard clear polycarbonate safety glasses will “work”.

      Soft glass lampworking does not generate any UV, and the amount of IR is negligible. The only issue is sodium flare (yellow ball of light), and that’s not hazardous, just very annoying (and can make it hard to see your work). If this is a one time deal for the class, then the clear poly glasses will work. If, however, the work with soft glass will be on-going, then I do recommend the AUR-92 filter so that the students can see their work.

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