EveJanuary 11th 2023

This post is mainly for those of you who are new to the practice of neon tube bending, and it’s about the difference between lead-free and leaded tubing. Or to be more specific, why you should not practice learning to bend neon using lead glass. Being newer to neon you may not even be aware that there are two different types, but the glass produced to make neon tubing used to contain lead. Around the mid-late 2000s, manufacturing regulations changed regarding the use of lead in glass tubing, and by 2010 only lead-free glass was being produced. It took about 10 years for the inventory of lead glass neon tubing to disappear from the shelves of sign suppliers and distributors, and now if you purchase new glass tubing for neon bending it is only lead-free glass that's available. This is important to know, because how you work the glass in the fire and how it behaves is different between the two types, and it requires adjusting your fires and modifying your bending technique in order to get the same results. It’s not a huge difference between the two types, but it's enough of one that I know of neon benders who got out of the business when the transition happened because they couldn’t adapt to the change. I also know of benders who left the trade years ago but decided to get back into it in recent years and are struggling as they try to re-learn how to bend with lead-free tubing. If you are practicing your bending and don’t know which type of glass you are using, or if you are bouncing back and forth between lead and lead-free while you are bending, you are going to struggle and your progress will be slow and frustrating. By now, you might be wondering what the difference is between lead and lead-free. Simply put, the older tubing that contains lead is easier to bend. It softens at a lower temperature and cools down slower, which gives you a longer working time to shape the bends. Lead-free tubing has a higher melting point and quicker cooling time and requires that you adjust your torches and work a little faster. If you are a beginner, make sure you know which kind of glass you are working with. There are a couple of different ways to check. The first (and probably the most common) is to turn the gas way up on your crossfire. If the glass starts to turn black as it gets hot, it's lead glass. Lead-free tubing does not turn black in the flame, no matter how gassy your flame is. In fact, you’ll need to crank up that gas if you want to get a good nice hot bend with lead-free glass. 

leaded-glass-stains-jpg - 1200 x 938
The blackening in the tube is caused by lead being deposited on the surface of the glass as a result of too much gas in the flame. This won't happen with lead-free glass.


 Another way to tell the difference between the two types which doesn’t require heating the glass is to look at the end of the tube. Lead-free tubing looks bluish/green on the end.

lead-and-lead-free-jpg - 1200 x 1182
Lead glass on the left, lead-free glass on the right

Obviously, you’ll need to have a sample of each type of glass in order to compare the two.  Here's another example.

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Lead-free glass is on the left here and the lead glass is on the right

Something important to mention when it comes to bending lead-free tubing is that you should make sure to wear didymium glasses. Not only will they protect your eyes from the sodium flare, but it also makes it much easier to see how the glass is heating and when it's time to make your bend.

Even though you can’t buy lead neon tubing new anymore, there is still enough of it out there that you will likely come across some. You can find it in old inventories of closing neon shops, or sometimes it’s donated to teaching facilities that use it for workshops or classes. If you are an aspiring tube bender and get your hands on some old lead glass stock, or maybe even some old dirty tubing that’s not good enough to use for jobs but you think it might be good for practicing your neon bending with, my suggestion to you is…DON’T DO IT!! It will give you a “false sense of ability”, as I’ve heard one seasoned bender put it. If you use lead glass to practice your neon bending (and maybe even get to the point where you’re thinking you are getting pretty good), as soon as you go to buy some neon tubing for a project and all you can get is lead-free, you will quickly find out that you are not as good as you thought and feel as if you are taking steps backward, becoming frustrated as you re-learn how to bend neon. In my opinion, learning to bend neon is hard enough as it is and it’s just not worth the aggravation trying to learn using two different types of glass. Do yourself a favor and set yourself up for success by using only lead-free glass for your bending practice. It makes sense to learn using the material that is currently available to buy (lead-free.) It might be harder, but once you become proficient at bending lead-free neon tubing, then if you do ever have the occasion to use the old lead glass you'll find it easier to adapt and with a simple adjustment of your fires, the glass will bend "like butter."

More information about working with lead-free tubing can be found here. https://www.brillite.com/UserFiles/File/Lead-Free_Tech_Bulletin.pdf

I would love to hear about your experiences working with either type of glass, so feel free to comment below!

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3 comments on "Get The Lead Out! (of your bending practice)"
RobertFebruary 24th 2023 @ 12:39
The chemistry behind the blackening of leaded glass is the result of the fuel-rich flame (a "reducing flame") needing to obtain more oxygen to fully combust all of the available hydrocarbons in the flame--the result is that is takes this oxygen from the lead oxides of the glass, which leaves the lead crystals behind as a silvery black deposit. The leaner pale violet colored flame (an "oxidizing flame") used when working leaded glass has enough excess oxygen in the airstream that the tendency of the gas to try to leach oxygen away from the lead oxides of the glass is mitigated. And, it is possible to get the lead crystals to go back into an oxidized solution in the glass by carefully reheating the blackened portion with a proper oxidizing flame--although this is certainly easier said than done.
EveJanuary 29th 2023 @ 11:31
Thanks David! And wow, that was so great of Mike. Although I'm not too surprised because I have always found him to be very helpful. Great customer service at FMS :) Incidentally, I'm looking at my profile image which is my logo and a great example of how the two different types light up. I used 12mm clear lead glass for the inner part, and 8mm clear lead-free for the outer section. At the time, I didn't know the color difference was going to be so dramatic and was upset when I first lit it up (I was expecting it all to look pretty much the same) but now I love the way it looks! :)
NeonPreservationJanuary 28th 2023 @ 23:39
excellent advice Eve, thank you for the informative right up! also, for those who may be interested in purchasing lead-free glass: i have a considerable stock of lead glass that i acquired when i purchased a used shop, but i have been hesitant to use any of it for practice. so, i recently contacted Mike Sweet at FMS to order several boxes of lead-free clear glass, and he arranged lift-gate delivery of my order to my residential address. he asked me what i was using the glass for, and when i told him it was practice, he threw on 3 additional 25 lb. boxes of 'defective' phosphor-coated glass for additional practice! he even called the day after the delivery to make sure everything went well. if youre interested in buying any quantity of glass, give Mike Sweet a call, he will treat you right!