Pickling with Sulphuric

[Clive HartlandParticipant @clivehartland94829]

Am I reading this right, mention of Sulphuric acid for pickling and suddenly talk of HF which i take to be Hydroflouric acid?

If so stay as far away as possible as it will be absorbed and enter your body via the skin, breathing the fumes is NOT good either. More clear detail of what is going on here please.  I only used it once to etch a graticlue, and was extremely wary of it. It was in a plastic bottle with the stopper off.

Clive

Edited By Clive Hartland on 04/11/2016 19:15:33

[JAParticipant @ja]

These normal acids (not HF) are safe if handled sensibly. However there are problems with them like do you want sulphuric acid fumes in a workshop or will you read the instructions for a brick cleaner.

I write this with thoughts of using caustic soda at above 100C.

JA

[Clive HartlandParticipant @clivehartland94829]

I used Aqua Regia once to etch numbers onto hardened steel, it was viscious and acted fast but even the fumes burnt ones skin. It turned out that soldiers were mixing up the breech blocks of the new SLR and causing headspace problems and I got tasked with doing something about it. 400 breech blocks later I was willing to run away after the fumes etc. I used a wax coating and using a spring stylus in a three dimensional engraver to follow the curve of the block. Only a little acid from an eyedropper was needed.

As a young soldier in REME i went through all the sections including plating and de-rusting. The best was stuff called Magnus 577 I think, it took everything off metal. Then there was the Black Chrome plating bath where I had to copperplate the item first. Did all the nuts and bolts on my M/cycle FOC. You learn a lot very quickly.

Clive.

[not done it yetParticipant @notdoneityet]

As a chemist, steer clear of concentrated acids (and alkalis) unless you know what you are doing. Treat all dilute acids with great care (proper ppe and other appropriate precautions). As above, steer clear of hydroflouric acid as it is extremely dangerous (tanker drivers used to be issued with scalpels to cut away tissue if splashed with the stuff!). It may still be used in wheel cleaners (low %), but I would not even use those products on principle.

Reactions can be different. Nitric can set fire to sawdust, while sulphuric will remove water and leave it as charcoal

Yes, we used chromic acid to clean our glassware at school and work, we diluted our concentrated sulphuric acid, used fuming acids. Aqua regia (conc hydrochloric/nitric acid), for dissolving gold and other precious metals, by the 50l carboy. On the alkali side, siliceous products were dissolved in molten sodium or potassium hydroxide (and dumped in hot water soon after it solidified!)

Glacial ethanoic acid is used in soap making and bought by beekeepers (for fumigation with 70% acid). Drain cleaners, as stated, are readily available. All quite safe, but only if you know what you are doing. Kettle cleaner is formic acid (another strong acid and also used by beekeepers).

In particular, you only have one pair of eyes. Don't lose your sight!

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 04/11/2016 20:58:29:

… by the 50l carboy.

…

Carboys! I'd forgotten about them. A giant glass bottle protected by some wire mesh and a handful of straw. I don't remember lots of accidents. Where they safer than they appeared to be?

Dave

[Sam Longley 1Participant @samlongley1]

Posted by SillyOldDuffer on 04/11/2016 21:16:27:

Posted by not done it yet on 04/11/2016 20:58:29:

… by the 50l carboy.

…

Carboys! I'd forgotten about them. A giant glass bottle protected by some wire mesh and a handful of straw. I don't remember lots of accidents. Where they safer than they appeared to be?

Dave

Although I did not see it myself I recall a teacher in our grammar school who had to fill some glass containers with acid from one of those for a class lesson. He rushed into the classroom where one was standing, grabbed the neck of the bottle & as he turned to carry it away the neck cracked & the bottle split splashing the contents all down his legs. he was seriously injured .

Cannot even imagine such a container being left in a classroom these days, yet we had several standing about in the science labs & dozens of jars with the glass stoppers of various acids on open shelves for lessons. Some were quite concentrated & we could only use them in the fume cupboards.

[JAParticipant @ja]

I remember teacher at school showing us what happened when you put red fuming nitric acid on warm dry sawdust. Nothing. We were told to leave the lab while he decided what to do next. Two days later he repeated the demonstration, a sudden very large violent flame that hit the ceiling.

There is worse, picric acid for example. After taking my A Levels two of us tried our hands at dying using synthetic dyes. It took me quite some time to get rid of picric acid burns. I think if any school now discovered the stuff in their store the bomb disposal squad would be called. It is still used for etching some fancy metals.

This obviously has nothing to do with the use of acids in the workshop.

JA

[not done it yetParticipant @notdoneityet]

Plastic carboys, not glass! It was only about 30 years ago, so moved on from the glass ones by then! Long lived because I still have two which are used to store diesel. Superceded by the IBC for chemicals, I suppose.

[Clive HartlandParticipant @clivehartland94829]

Carboys, we carried two carboys of Sulphuric acid in our REME workshop lorry. This used for battery maintenance. Oh yes, frost and ice on the Autobahn and lorry skids and turns over. Two carboys smashed all over the road and an Acetyline gas bottle securely stuck in between the two rails between the dual road.

The acid soon was spread by cars going past and was stinging my face and obviously getting on my clothes. Was given instructions to clear up the mess and set to. Got the vehicle righted and luckily all the glass was in the box that the carboys were in. The gas bottle was retrieved by spreading the barrier with some wood. All the while cars going past. Got to our location and asked the cook for Soda and put all my gear in it and had a shower but no serious problems.

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