Chemical Etching of Glass

As we are probably all aware … The chemical of choice is/was hydrofluoric acid; which comes with some serious safety-hazards.

I was therefore surprised to see [in a crafting magazine that my wife was reading] this product advertised as being approved for use by twelve-year-olds :

**LINK**

https://etchall.com/product/etchall-etching-creme-5/

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It turns out that the active ingredient is Ammonium Bifluoride :

**LINK**

https://frantzartglass.com/images/Etchall%20Dip%20n%20Etch%20Liquid%20MSDS.pdf

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Not a substance with which I am familiar … So I would be interested to know what the forum’s Chemists think.

MichaelG.

No idea myself, but seems to be available from UK suppliers e.g. this one

https://www.creativeglassshop.co.uk/product/31199/etching-solution-118ml.html

Bill

Ammonium Bifluoride? So uses the Flouride ions to do the etching, presumably.

Still the thought of a 12 y o handling it seems a bit dodgy, but maybe I'm just windy!

Howard

Ammonium Bifluoride can irritate/burn your skin and I would not inhale it, more info here.

Thor

The original post referred to a product where there the ammonium bifluoride is in the form of a cream or paste and thus less likely to splash. Even so, good safety specs or a full face visor, proper gloves (i.e. Marigolds rather than a thin disposable gloves) and a plastic apron. There is an interesting discussion at https://www.finishing.com/94/62.shtml.

Thanks, Dick … that’s very helpful

MichaelG.

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It makes reading this all the more interesting :

https://acmiart.org/index.php/art-material-safety/safety-tips-what-you-need-to-know

Edited By Michael Gilligan on 25/10/2021 14:00:05

Hi, being a chemist for more than 45 years I would not let it near a child or adult outside of a workplace or laboratory where people have access to an antidote and have been trained. Those using HF to dissolve rocks used to say its better to not wear gloves as if you have a pin prick you won't know it as HF and ammonium bifluoride / ammonium fluoride does not burn the like sulphuric etc. By the time you feel the burning sensation it will be too late and you can't just wash it off. You also have inhalation hazards with these compounds which can be severe.

Using the ammonium bifluoride as a paste is marginally safer than HF as its less concentrated in terms of fluoride ion concentration. On contact with water it ionises to produce the acid F and H ions hence is acidic. As you say the F attacks the glass,

I hope this help Barry

The above said, it was being used in the USA for cleaning car wheels at car washes until 2000!

That helps a lot, Barry … Thank You

I still find it astonishing that they have cleared it for use by twelve-year-olds, when the modern world sometimes seems totally paranoid about chemical safety.

MichaelG.

When you can't even buy a tube of Evostik off the shelf anymore it 'beggars belief' this stuff is considered safe for children to use.

Industrially, they die up here on Humberside with accidents of similar material.

When replying I forgot to mention an incident that happened in our lab back in 1988. A cleaner who was not very with it pinched a 1l bottle of HF acid and fortunately told his flat mate that he had decanted it into small plastic tubes so that he could throw it at potential attackers on the tube/streets. Fortunately, he had his collar felt quite quickly by the bill and we got it back. Things are now much tighter although I sometimes regret this when needing to do some case hardening .

Barry

As a child I was given an old "boy's book of chemistry" by a lab technician at Oxford University. One of the many dangerous experiments in it was to etch glass. The instructions were to ask your dentist for some old teeth, grind them up and place in a evaporating dish with some strong acid (was probably nitric), place the glass with wax resist on top of the dish and heat to produce hydroflouric acid fumes! It also described how to make and explode picric acid! I avoided the most dangerous experiments but did make some nitrogen tri-iodide. Those were the days!

Russell

I used to have a book of microscopy techniques for amateurs. It described subliming realgar (arsenic trisulphide) on to a microscope slide for mounting diatoms. It was the preferred medium due to it’s high refractive index for counting the dots. Not something I would do without a fume cupboard!

It was also used as an artist’s pigment - must have made a few people rather ill.

Niall

I've used a similar product to remove partially damaged coating from a pair of spectacles to make them usuable enough to get another year's use out of them (tightwad).

I treated it with considerable respect.

Neil

The coating on glasses doesn't seem to adhere so well on modern plastic lenses. Mine have just become unwearable after only two years.

Russell

Hi there, all,

I still have a mostly full tube of black Bostic in a safe place. I guard it carefully. For some jobs it works like no other.

The glue sniffer nutters ruined a lot of things for a lot of us!!!!!!

Best regards,

Swarf, Mostly!

Russell , surely your prescription is out of date by then!!