Hobby Lobby, Michaels, WalMart sell ‘Armour Etch’ Glass Etching Cream. It contains some less-than-frightening portion of hydrofluoric acid, which etches or ‘eats away’ the surface of most glass. Handled with reasonable care, you can safely etch a quality design or whatnot. However, brushing or smearing a layer of this cream onto a broad lens surface would probably leave obvious blotches or streaks.
‘Etchall dip ‘n etch’ liquid might work better if you submerged and swirled the lens in it for a few seconds. I would suggest masking the outside of the lens, and only etching the inside surface.
Like dchomak said above, ‘Whink’ and some other laundry stain removers include small amounts of hydrofluoric, and may produce a slight frosting over longer time.
I remember when I was a child, a door to door pot and pan salesman came and gave a demonstration of Stainless Steel cookware. He was pitching his SS pots against Aluminum. Part of his demo included boiling some water with baking soda and then pouring the mixture into a cheap water glass. About a half hour later the inside of the glass became etched. Imagine what that would do to your stomach, he said.
I remember that thread Alex.
I had decent results etching below the filament only.
Caution and protection are the watch words when working with that stuff.
The easiest, safest way to get a frosted glass is to use carborundum powder from a lapidary supply (where it is used for grinding and polishing) 400-600 grit (I use 500) sprinkled on a piece of glass, add a bit of water and with a circular motion, grind your piece of glass on top of this. About 15-20 minutes will produce a nice even frosted glass on both the top and bottom surface.
I have used this method to make camera ground glass up to 8X10 inches, perfectly even and smooth.
We did that in freshman chemistry lab. We let it work at least over night, so probably in lower concentration. They warned us that our finger tips would fall off if we handled it without gloves. It is not the acidity that makes it dangerous but the concentrated and mobile F- ions. There are probably safer ways to frost things, but the results might be very good.
I tried some etching myself and failed miserably. It’s one of the reasons I went down the diffusion film road! At least I didn’t burn or dissolve myself.
I did my PhD in fluorine chemistry, and have extensive experience with hydrofluoric acid. I don’t want to go into the gruesome details of accidents with hydrofluoric acid, but even small mistakes can be VERY painfull, so be aware of the consequences.
Etching creams are a viable solution and can be handled safely when instructions are followed, but honestly, I don’t think it’s worth the hassle.
Firstly, as mentioned above, not every type of glass can be etched to the desired results.
Secondly, there are so many DIY-solutions that are so much easier and can be done with household materials in literally 5 minutes. Diffusion film has been mentioned (I have also used the ‘invisible’ type of scotch tape, works very well and is removable), or sanding the lenses with carborundum sandpaper, or glass frosting spray (also removable and can be applied in several coats to intensify the effect).
Don’t let me keep you from doing a bit of chemistry at home, but be safe!
ditto to the above - HFl is seriously scary stuff. We had a small bottle of it in the lab and everyone was very happy when EHS came and picked it up for disposal. I’d rather gargle with ethidium bromide than touch that stuff.
Whew, really? I mean, hydrofluoric acid is very toxic, yes, but it can be handled. Gargling ethidium bromide on the other hand would leave you with, I dunno, three tongues or worse
Ethidium bromide has long been thought to be very dangerous (mutagenic), but after thirty years of use in molecular biology labs there are still no studies that support a high risk for humans, especially not in the the low concentrations used in the lab. I hope it stays that way because in my younger years I used the stuff quite carelessly in the lab :-(
not to get side-tracked further, but the “is EtBr really all that dangerous” thing has never really been resolved. All the safety studies were done in mice and rats, most likely at higher concentrations in order to screw them up quickly, but then again, it’s a DNA intercalating agent! That’s got to give anyone the willies, right? I’d just rather use one of the variety of other DNA dies on the market - they’re not that expensive and they don’t run off the gel either.
All the people with personal experience don’t seem to be speaking. The stuff is the honey badger of toxins… it’s bad ass stuff. And don’t even think that gloves will protect you.
