[mudassir]

Hi there,

I want a safer industrial alternate to hydrofluoric acid for etching/frosting flat glass. We've planned to launch new products with frosted glass in the market and all I know is that hydrofluoric acid is used to etch / frost glass but it is dangerous to tissues/bones/eyes and environment.

I want no injury to my team/workers can anyone suggest me safer alternate?

Also I want to declare that all the stories I heard about the dangers of hydrofluoric acid are from research on internet with no practical experiment done. We commonly use ferric acid, sulfuric acid and nitric acid for different production processes. So, any comparative information on dangers of hydrofluoric acid vs. sulfuric acid will also be helpful to us.

[Arkcon]

There isn't really a safer way to etch/frost glass than hydrofluoric acid.  And yes, the hazards associated with HF are severe.  The best way I've seen to minimize the risks is to use engineering controls -- keeping the reagent under control, and being prepared for a possible accident with adequate training and safety precautions.  With a little digging, you should be able to find industry standard information on the reagent, its hazards, and safety.  I will (later on) dig through my archives and see if I can't find some information that's sourced well.

[Doc Oc]

There was some discussion on another blog about HF and its dangers recently.  Don't know about any safer alternatives though, I think Arkcon may be right in suggesting you just need to minimize the danger as much as possible.

http://blog.chembark.com/2012/02/14/wwwtp-hf-stupidity-on-house-m-d/

[Honclbrif]

Most mineral acids (sulfuric, nitric, etc) mainly represent corrosion hazards. HF is different in that it is intrinsically toxic. It can also penetrate nitrile gloves and skin.

As Arkon said, engineering controls will probably be the best way to go. You should also read up on the industry standards and best practices on safely handling HF. It can be dangerous, but people have been working with it safely for a very long time.

[mudassir]

There isn't really a safer way to etch/frost glass than hydrofluoric acid.  And yes, the hazards associated with HF are severe.  The best way I've seen to minimize the risks is to use engineering controls -- keeping the reagent under control, and being prepared for a possible accident with adequate training and safety precautions.  With a little digging, you should be able to find industry standard information on the reagent, its hazards, and safety.  I will (later on) dig through my archives and see if I can't find some information that's sourced well.

Thanks for reply. Yes, hf is best available solution to etch/frost glass. I'll search for handling & safety instruction also anymore information from your end will be awaited.

[mudassir]

All I knew for safety is:

1. Ventilation is required: Good to work in open space
2. Avoid any skin contact: use rubber gloves & sweatshirts
3. Do not inhale
4. Harmful to eyes also: use goggles

Now, if the chemical (hf) is contacted with the skin of a worker in small amount (lesser than 2 drops), then is that case washing effected area with soap will work. In the safety instructions, I also read "caustic soda" can be used to wash walls or ground effected by hf. Can we also use caustic soda in hf to penetrate it before waste?

[Arkcon]

Caustic soda is a good thing to have around when working with HF.  Any base, and caustic soda is an inexpensive one, will neutralize HF into a neutralized fluoride.  I would often wipe down the general area where HF was used with 1 N NaOH before wiping it down with water, just in case.  I would then tell people, "There, I've spread around caustic, so everyone is safe.  Heh.   Funny definition of 'safe'"  But I did convert a flesh eating, bone dissolving, systemic toxin into a corrosive, skin irritating, systemic toxin.  So that's some sort of a win.

It would be preferable to work in a fume hood.  Most of the area enclosed, except your hands and arms, with strong ventilation to outside the building.  Gloves are required.  We used double gloves, and peeled off the outer pair when done.  Disposable sleeve covers are also available.  A lab coat, or waterproof apron are a better choice than an absorbent sweat shirt.

To protect exposed skin, the solution is washing, and a calcium gluconate gel.  That's a permeable calcium rich gel, so the HF reacts with it, instead of the body's own calcium reserves.

[Arkcon]

Here's a reference I was required to read and sign off on before I was allowed to work with HF.  You might try to look up the source document for yourself as well.

[mudassir]

Caustic soda is a good thing to have around when working with HF.  Any base, and caustic soda is an inexpensive one, will neutralize HF into a neutralized fluoride..

Thanks! I'm almost ready to use hf, all I need to search for is "calcium gluconate gel" in local market (if available). One more question, does hf make vapors when exposed in air and how harmful those vapors are if yes.

[mudassir]

Here's a reference I was required to read and sign off on before I was allowed to work with HF.  You might try to look up the source document for yourself as well.

Thank you very much Arkcon.... I'm really thankful for your kind support

[mudassir]

I want your help once more, I want to know:

1. When exposed to air, HF will positively produce vapors. How much dangerous they'll be if yes.

2. What do you exactly mean by 1 N NaOH. I mean how much caustic soda will be required to neutralize 1 liter of HF for example.

[billnotgatez]

Any base, and caustic soda is an inexpensive one, will neutralize HF into a neutralized fluoride.

Is the reaction of caustic soda and HF highly exothermic?
Would baking soda be better?
(real questions not socratic)

[mudassir]

Hey Arkcon,

I tried hf (40%) with 3mm and 2mm glass sheets. I gives excellent results. Thanks for your kind support. Also by a practical experiment, I knew about hf more clearly. It is really dangerous even while I used the lowest degree of the chemical in the market. I'll show you the resulted sheets after I treat them with colors

Can you please be specific on what chemicals/bases are used to reduce/extend the degree of hf as there are two solutions available in our local market one is hf 40 and the next one is hf 60. And also I would like to know how dangerous is hf 40 while compared to pure hydrofluoric acid?

[mudassir]

Any base, and caustic soda is an inexpensive one, will neutralize HF into a neutralized fluoride.

Is the reaction of caustic soda and HF highly exothermic?
Would baking soda be better?
(real questions not socratic)

I'm not a chemist at all but by a practical experiment of hf 40, I came to know that it was not that much exothermic with caustic soda. But reacted with water more dangerously. What I did to clean treated glass sheets, is....

1. Rinse them with fresh water.... two or three times.
2. Washed them with caustic soda.

An expert chemist will be more specific on the reactions of caustic soda and HF and also on if I was correct

[billnotgatez]

@mudassir
Actually, my question about caustic soda was more for the persons helping you, but your input does help me understand

by the way
did you rinse them again with water after you applied the caustic soda?