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In short - engraving borosilicate is difficult, because it does not expand very much when heated. So when hit by an infrared laser beam, the glass doesn't loca

In short - engraving borosilicate is difficult, because it does not expand very much when heated. So when hit by an infrared laser beam, the glass doesn't locally expand and spall off a tiny speck of glass .... instead, the glass locally melts. When the beam moves on to the next pixel, the first site either solidifies or sometimes dribbles away. Laser engraving of borosilicate just doesn't work well. And, because of the compound curves of the Klein bottle, you need a big depth of field as well as a rotary bottle holder. All laser engravers that I've played with have a very short (10mm or so) depth of field. Diamond engraving doesn't work well because of the curves. Sandblasting with a rubber mask works, but making the mask is a pain. So, after lots of attempts, I've given up on engraving these guys. Also: mistakes are expensive -- this is hand-blown glass.

dlgeek 7y ago
(Everyone should make sure to note the name on the above comment) Thanks for answering, and congratulations on your book's anniversary. My job gives out copies of your book as a somewhat prestigious award to those who find and report security problems, and I'm very happy to have both received and read a copy.
numlocked 7y ago
This is basically exactly what you told me on the phone :) We also had a fun digression about sand-blasting tombstones. And of course, we covered the hand-engraving/dremel option. So...label maker.
pmoriarty 7y ago
Can't acid be used to etch glass? Also, why not use glass that's easier to etch?
- wnkrshm 7y ago
  With quartz glass, it's going to be hydrofluoric acid and I invite you to read up about its toxicity and lethality (user stories like: splashed a few ml on a leg, did all the emergency procedures exactly right, got quick emergency care, leg amputated, died anyways).
  - snuxoll 7y ago
    S04E20 of ER had a patient die due to contact exposure to hydrofluroic acid, I had to look it up after reading this comment to make sure I got it right - don’t know why but it’s one of the most memorable to me. Seriously, don’t mess around with this shit - even IF you notice exposure (hard, because you may not even notice until it’s too late) there’s a good chance it’s already a done deal.
    - wnkrshm 7y ago
      I'm glad that I don't have to work with the stuff after reading up on emergency medical procedures. I once found a very long list of what to do by an expert MD and it's really not pretty. I'm not an expert in either chemistry or medicine but what I gathered was: The medical team needs to try and offset what the fluor is doing to the balance of ions in your body, to keep your cells alive. HF will diffuse within pretty much all of your tissues (including diffusing into bone like it was a sponge iirc) and a medical team will check your blood ion levels every five minutes or so while sticking you with CaCl (iirc) injections along the path the HF may diffuse through your body (if you're lucky enough to have hit an extremety like a hand). While the HF is diffusing, you will not feel anything. They cannot just pump you full of the proper ions to counteract the effects of the fluor and maybe bind it because that would kill you as well, they have to hit the right elevated concentration locally to offset what the fluor is doing. Edit: I've read up on it again and some of the things I wrote aren't right and I misremembered, like HF exposure being painless. At first it may be so but once the calcium levels drop, exposure is connected to extreme, "deep" pain. Treatment guides stress to not admister aneasthetics because the pain is the best indicator for successful treatment. Also, Calcium Gluconate is recommended, not Calcium Chloride. This [0] is a detailed source I found (PDF). [0] (PDF) https://ehs.unc.edu/files/2015/09/hfaexposure.pdf https://ehs.unc.edu/files/2015/09/hfaexposure.pdf
    - glandium 7y ago
      Hydrofluoric acid is also what they use to dispose of bodies in Breaking Bad, although they did exagerate the effectiveness.
      - 7y ago
ringshall 7y ago
Could you combine laser engraving with a jet of air, to blow away the molten glass?
- Doxin 7y ago
  AFAIK basically all laser engraving/cutting is air assisted already. Turns out smoke is really good at getting in the way of lasers, and air is a really good way to get rid of it. That said I don't know if it'd be a firm enough blast of air to move any significant amount of molten glass.
jkaunisv1 7y ago
I've used my laser cutter to cut a mask for acid etching when the laser itself couldn't etch the material needed. How thick is the rubber you use for sandblasting? Could it be laser cut to reduce the pain of making the mask? It sounds like you've exhausted all workable options but my curiosity is piqued.
thecyborganizer 7y ago
I currently work in the laser engraving industry, and I can confirm everything you've said to be true. However, I wanted to let you know about some extremely cool technology that I had the opportunity to experiment with a year ago or so. Some companies have developed optics with adaptive focus that use liquid lenses to mark beyond a 10mm depth-of-field - see https://www.optotune.com/technology/focus-tunable-lenses https://www.optotune.com/technology/focus-tunable-lenses for an example, and https://youtu.be/ss-tkXcClMk https://youtu.be/ss-tkXcClMk for a video of the system in action. I still don't think it would work well for your purposes - borosilicate just doesn't mark well, and you'd need to start with an accurate 3D model of the object - but I hope you enjoy the video! (And thanks for writing the book!)

dlgeek 7y ago

(Everyone should make sure to note the name on the above comment) Thanks for answering, and congratulations on your book's anniversary. My job gives out copies of your book as a somewhat prestigious award to those who find and report security problems, and I'm very happy to have both received and read a copy.

numlocked 7y ago

This is basically exactly what you told me on the phone :) We also had a fun digression about sand-blasting tombstones. And of course, we covered the hand-engraving/dremel option. So...label maker.

pmoriarty 7y ago

Can't acid be used to etch glass? Also, why not use glass that's easier to etch?

wnkrshm 7y ago
With quartz glass, it's going to be hydrofluoric acid and I invite you to read up about its toxicity and lethality (user stories like: splashed a few ml on a leg, did all the emergency procedures exactly right, got quick emergency care, leg amputated, died anyways).
- snuxoll 7y ago
  S04E20 of ER had a patient die due to contact exposure to hydrofluroic acid, I had to look it up after reading this comment to make sure I got it right - don’t know why but it’s one of the most memorable to me. Seriously, don’t mess around with this shit - even IF you notice exposure (hard, because you may not even notice until it’s too late) there’s a good chance it’s already a done deal.
  - wnkrshm 7y ago
    I'm glad that I don't have to work with the stuff after reading up on emergency medical procedures. I once found a very long list of what to do by an expert MD and it's really not pretty. I'm not an expert in either chemistry or medicine but what I gathered was: The medical team needs to try and offset what the fluor is doing to the balance of ions in your body, to keep your cells alive. HF will diffuse within pretty much all of your tissues (including diffusing into bone like it was a sponge iirc) and a medical team will check your blood ion levels every five minutes or so while sticking you with CaCl (iirc) injections along the path the HF may diffuse through your body (if you're lucky enough to have hit an extremety like a hand). While the HF is diffusing, you will not feel anything. They cannot just pump you full of the proper ions to counteract the effects of the fluor and maybe bind it because that would kill you as well, they have to hit the right elevated concentration locally to offset what the fluor is doing. Edit: I've read up on it again and some of the things I wrote aren't right and I misremembered, like HF exposure being painless. At first it may be so but once the calcium levels drop, exposure is connected to extreme, "deep" pain. Treatment guides stress to not admister aneasthetics because the pain is the best indicator for successful treatment. Also, Calcium Gluconate is recommended, not Calcium Chloride. This [0] is a detailed source I found (PDF). [0] (PDF) https://ehs.unc.edu/files/2015/09/hfaexposure.pdf https://ehs.unc.edu/files/2015/09/hfaexposure.pdf
  - glandium 7y ago
    Hydrofluoric acid is also what they use to dispose of bodies in Breaking Bad, although they did exagerate the effectiveness.
    - 7y ago

ringshall 7y ago

Could you combine laser engraving with a jet of air, to blow away the molten glass?

Doxin 7y ago
AFAIK basically all laser engraving/cutting is air assisted already. Turns out smoke is really good at getting in the way of lasers, and air is a really good way to get rid of it. That said I don't know if it'd be a firm enough blast of air to move any significant amount of molten glass.

jkaunisv1 7y ago

I've used my laser cutter to cut a mask for acid etching when the laser itself couldn't etch the material needed. How thick is the rubber you use for sandblasting? Could it be laser cut to reduce the pain of making the mask? It sounds like you've exhausted all workable options but my curiosity is piqued.

thecyborganizer 7y ago

I currently work in the laser engraving industry, and I can confirm everything you've said to be true. However, I wanted to let you know about some extremely cool technology that I had the opportunity to experiment with a year ago or so. Some companies have developed optics with adaptive focus that use liquid lenses to mark beyond a 10mm depth-of-field - see https://www.optotune.com/technology/focus-tunable-lenses https://www.optotune.com/technology/focus-tunable-lenses for an example, and https://youtu.be/ss-tkXcClMk https://youtu.be/ss-tkXcClMk for a video of the system in action. I still don't think it would work well for your purposes - borosilicate just doesn't mark well, and you'd need to start with an accurate 3D model of the object - but I hope you enjoy the video! (And thanks for writing the book!)