elkdoc

Safety glasses for forging...

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On 9/26/2019 at 10:28 AM, JHCC said:

Sodium produces a bright yellow flame when heated sufficiently; you may remember this from flame tests in chemistry class. You see this a lot in glassblowing with soda-lime glass. 

I use salt to test for critical temperature in heat treating (its melting point of 1474F is closer to the 1450F-1500F necessary for complete conversion to austenite than the usual 1413F at which steel becomes nonmagnetic), which almost always turns the dragon's breath of my propane forge to a yellow-orange.

intersesting but the color from hot glass isnt from the sodium(thats in solution with the rest of the glass) its from the temperature! the radiant heat is discharging photons. the color is a result of that. if the sodium in glass is 'burning' then youd have to be upwards of 5000º and the glass would be chemically transformed into fulgerite. the photons are what the neodymium is filtering, it polarizes the light.

when you add neodymium to glass(to make the lenses) it changes the way light travels through it. when you look at hot glass through it ,the harmful range of uv light is prevented from traveling through the glass to your eyeball, it gets returned by the neodymium, in layman's terms.

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How does any UV light come from it? it is IR that we are trying to stop here

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Glass Blowers Cataracts are an IR issue unlike arc welding which causes UV issues.

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Perhaps you should do more reading than writing, gwyn you have your facts very wrong and this isn't the first time. Have you ASKED a glass blower what causes the bright yellow flare? 

There is NO UV generated in a fuel air fire, oxy fuel generates high enough in the blue to be a hazard still not UV. 

Trying to impress people often has the opposite effect.

Frosty The Lucky.

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Could be some confusion regarding types of glassblowing.  In off-hand glassblowing there is a tank of molten glass that under working conditions runs at around 2,100 deg. F for soda-lime-silica (hard) glass.  The glass is worked at that temperature , or below.  For torch work with borosilicate (soft) glass you need to work much hotter, and have the blue/white torch flame to contend with as well.  I understand there are some glassblowers that are now melting borosilicate for off-hand work, but that wasn't very common back when I was a professional glassblower. 

At that time I used prescription didymium  glasses for my off-hand work, but had an additional tinted shield in front of my glory hole so I could monitor the work during reheating (unlike forging, you can't just throw it in and wait till it gets heated up .  Unfortunately my prescription has changed over the years, so I can no longer use those glasses for forging.  I try to avoid staring into the forge when reheating, especially at forge welding temperatures, as taught by Mark Aspery in a recent class I attended.  Makes a big difference on how well I see things in the shop after heating.  I know some smiths who work longer in the forge than I do use tinted glasses, but I haven't gotten around to it yet.

Worst eye damage I got in my glass career was using single part optical grade glue systems that had to be "set" with UV light.  Didn't have side shields on my didymium specs and the high intensity black light I used got in around the corners.  Sunburn on your eyes is no laughing matter... 

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hi so i have been a glass worker for 30 years and i run a glasscasting facility with a 2500 lb furnace and 15 ovens.I also have an overhead sand foundry with a 3000 lb tilt and an investment casting facility as well,we specialize in glassblowing and large scale glasscasting in crystal. I also do very large bent glass i worked for about ten years in a factory blowing glass. ...usually i downplay my knowledge so people dont think im tooting my own horn which i hate, but in this case Frosty, its probably better for me to share that info with you to give my replies some more consideration. again the sodium in glass does not produce any orange that woudlnt be produced from any other item heated to the temperatures needed to produce orange light UV IR etc. the IR is what dmages and that spectrum is diminshed by neodymium. As posted above by Lattecino (ciao bella che figato!) he is correct. the types of glassworking that most need neodymium glasses are the lampworkers who are using borosilicate with a torch. the furnace work that i do requires lower temps and lower colors as a result. not to toot my own horn but if there is a topic i am familiar with it is the chemical and working properties of glasses and metals. its how i eat.

also for the most part teh light were concerned with in foundry, glassblowing and forging is infrared not uv although welding produces a lot of that. i guess what im saying is that the lenses pare controlling the type of wavelength that is allowed to pass through, glass is amazing since its one of a few materials that photons can pass through. this is how we use it to block light waves. that is important to know since the infrared light is what is the most damaging and the most present in glassblowing and other hot work.

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It's important to wear the correct type of protective glasses for what you are doing and know that what works for one task my be worse than useless for another:

So *ARC*welding requires MANDATORY UV protective glasses/shields/clothing!!!!

Gas welding and forge welding and forge work require IR protective glasses and shields.

Many people have been confused and think that one will protect against the other. This is simply not true!

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I have a friend who maintains and repairs industrial lasers. He has a stack of stickers in his toolbox that say 'Do NOT look at laser with Remaining eye".

The maintenance clients get fresh stickers every year.

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