Pickle Strength

[havoc]

Buying acid seems to be easier in the UK than in Belgium. When I asked for battery acid in a car shop, they first said they didn't have any. Then after some probing admitted they did have it, but not in the racks. Since the reason I wanted it seemed OK to them they let me have a bottle 35% stuff. I have never seen HF fo sale anywhere, and I find it best that way. Just as nasty stuff.

I think I'm going to try the meths and amonia mixture.

For the chemists: I saw once copper being cleaned by just putting it in a bath, and it turned clean as soon as it entered the bath. I seem to remember this was in boiling meths. Is this possible? (I know this isn't very safe but I always see that piece of tube turning bright instantly)

[Deleted]

Hi

I bought some battery acid from the motor factors, and diluted it about 2 parts water to 1 acid, I think I got these proportions from an LBSC book, it seems to work fine.

Also from Alec Farmer's boilermaking book, he recommends pickling to remove easyflo flux, but for sifbronze flux, to leave it overnight in plain water

Regards
Trevor

[the_viffer]

havoc said:

I think I'm going to try the meths and ammonia mixture.

For the chemists: I saw once copper being cleaned by just putting it in a bath, and it turned clean as soon as it entered the bath. I seem to remember this was in boiling meths. Is this possible? (I know this isn't very safe but I always see that piece of tube turning bright instantly)

Have fun with the meths and ammonia. It is commercially available as Horolene. It really is astonishingly smelly (it was your tubes not metal ones I meant being cleaned out). You'll need to do it outside and even then you may find your eyes streaming and your sinus feeling like they are being steam cleaned. (I spent some time working with mercaptans which are among the smelliest compounds known. Think skunk stuffed with sprouts and boiled for a week. I never seemed to have a problem in getting a seat at cinema but I did find it hard to get a girl to come too!)

I'd not expect copper to be cleaned by boiling meths (the meths is to help dissolve oil and lacquer). Nitric acid is one possibility (Try and buy that and expect a hard questioning and possibly a visit from the police). I'm not sure but liquid ammonia ie ammonia gas cooled down until it turns into a liquid would posisbly work too. If you find out I'd be interested

[the_viffer]

viffer said:

havoc said:

I think I'm going to try the meths and ammonia mixture.

For the chemists: I saw once copper being cleaned by just putting it in a bath, and it turned clean as soon as it entered the bath. I seem to remember this was in boiling meths. Is this possible? (I know this isn't very safe but I always see that piece of tube turning bright instantly)

Have fun with the meths and ammonia. I forgot to say you need to add some detergent and to dilute the mixture with water. It is commercially available as Horolene. It really is astonishingly smelly (it was your tubes not metal ones I meant being cleaned out). You'll need to do it outside and even then you may find your eyes streaming and your sinus feeling like they are being steam cleaned. (I spent some time working with mercaptans which are among the smelliest compounds known. Think skunk stuffed with sprouts and boiled for a week. I never seemed to have a problem in getting a seat at cinema but I did find it hard to get a girl to come too!)

I'd not expect copper to be cleaned by boiling meths (the meths is to help dissolve oil and lacquer). Nitric acid is one possibility (Try and buy that and expect a hard questioning and possibly a visit from the police). I'm not sure but liquid ammonia ie ammonia gas cooled down until it turns into a liquid would posisbly work too. If you find out I'd be interested

[stevep]

In response to some of the recent posts.

The flux removal process recommended by Johnson Matthey is caustic soda. I was able to buy a carton of crystals from our local hardware superstore, and it works a treat.

Several of my colleagues use citric acid, but I prefer sulphuric - but more for cleaning the copper than removing the flux. As someone said, a lot of the flux will come off if you put the piece in really hot water.

I would urge caution about leaving a boiler in the pickle too long. When I built one of my boilers, I couldn't get the whole thing in the drum, so did one end first, and then the other. When I removed the boiler after the first end, there was a distinct corrosion mark at the air/surface join. (Like the wasting on stays under use).

Finally, I use the acid pickle bath to clean up steel parts after silver soldering. Sure it copper plates the material (and it only needs to be left for a while - 1/2 hour max), but it takes off the black scale formed during heating.

Cheers...Steve

[Jo]

The copper plating on the steel normally washes off really easily, but then the rust bug gets in really quick.

I wonder if this may also be a suitable preparation technique prior to painting?

Jo

[Noddy]

a few thoughts:

Yes, by all means use an alkali pickle if your solder manufacturer recommends it, but...

zinc, cadmium and tin dissolve in alkalis (there are all sorts of tales of fine double barrel shot guns, soldered on sights etc coming to pieces in an alkali bluing bath or degrease bath) so watch out with tin & zinc contained in solders or brazing.

Hyperchlorite bleach, washing soda, sodium hydroxide etc all make good galvanizing and tin plate removers from steel. (cadmium comes off the same as zinc).

Citric acid was going for about £8 for a 25kg bag during the foot and mouth (it was the main ingredient for disinfecting, the bug can not stand Ph below about 5 (although it looks pretty clear now that it was being spread deliberately, or at least deliberately allowed to spread by our "lords and Masters")). the foot wash outside my old man's gate lasted about a year before the rain diluted it enough for the slime to grow. Citric would be my 1'st choice for pickle. Salt was supposed to make it more active on metal, but I'm not certain of the truth of that, I suspect it was more for the scouring effect of the salt crystals.

Ammonia is used in getting the copper fouling out of rifle barrels, and will attack copper but leave the steel untouched, so long as you don't leave it in there too long. Copper will complex with the ammonia, (dissolve completely) as long as the solution is concentrated enough.

Ammonium persulphate with lots of ammonia is used to remove nickel plating, and as long as there is enough ammonia, it will not harm the steel.

Copper, rusty steel, silver etc can be cleaned a treat in an old aluminium foil container (e.g. pie dish, zinc works as well) just have the metal in contact with the aluminium, and put an alkaline solution in (hot sodium carbonate (washing soda) solution works well. The Aluminium reacts to release hydrogen and the electrolytic effect loosens rust or sends sulphide tarnish off as a cloud of H2S (best done outside).

Back to Acids
Sulphates will trash concrete, both by the disruptive effect of gypsum crystals growing in the structure and in reacting with the other minerals in there. Concrete that has been exposed to soluble sulphates pretty much turns to mud. chlorides are not that much better.

Sulphuric is also a bastard for putting holes in clothes. H2SO4 has such a high boiling point that unseen spats loose their water and end up pretty concentrated, and burn...

Nitric and nitrates, expect a call from the boys in blue, you can't even get saltpeter for curing bacon now.... Red fuming nitric is great for getting things to rust and for taking rust stians off glass though, and as all nitrates are solouble, it washes out and doesn't give persistent rusting. Flesh burns from red fuming nitric are something else. Deep, really painful and take ages to heal.

Hydrochloric. Hideous stuff for making everything around it rust for ever more. you can get it from swimming pool supplies if the chemist won't let you have it.

Phosphoric: The main ingredient in things like "jenolite" rust remover. Dairy farmers get the stuff in 5 gallon+ drums as "milk Scale remover". Iron phosphate is insolouble and will give good rust protection if you can impregnate it with waxoyl (manganese and zinc phosphates too, under trade names like "parkerising" See Angier; firearms bluing and browning for the potions). Phosphoric is quite a "safe" acid, a friend calmed her revolting workforce by diluting some and drinking it when her (his at the time, but that is another story) guys refused to work with "ACID!". the stuff is the active ingredient in coca-cola coin cleaner (you don't drink that stuff? do you?), and not poisonous in the ammounts we use. it is also pretty innocuous on skin.

Hydrofluoric:
A guy I know used to sell rust remover with the stuff in it. We almost fainted when we heard. if you get it on your skin, by the time it starts to tingle, it will have killed the bone below it and you will need an amputation. The fluoride ion is so small it diffuses really quickly through skin and it is fiendishly toxic.

The paste you get from welding shops for removing the discolouration from welds in stainless steel usually contains nitric and hydrofluoric acids. If you must use it, have your hands covered in calcium borogluconate cream under thick rubber gloves, and, if you get it on your rubber gloves, change them immediately, it will diffuse through them and into you in a flash!

Comercially, fluorspar (CaF2) is shipped around the world rather than the acid.....

Chemists who work with it often eventually loose fingers, or worse. My old mother (as mothers do) refused to believe me when I told her to be careful not to touch the stuff when she went to a glass etching demonstration.

A place I used to work used the stuff when analysing silica sand. They looked at the possibility of doing the analyses at a remote site to reduce turn around time, but, even with a helicopter ambulance, they thought that it was still too risky for the technician if there was a spill.

Biological effects aside, HF passivates steel, and was used as the preservative in fuel tanks of some rockets. Useful but nasty.

Oxallic acid.
Available as Kettle de-scaler. It is also the acid in Rhubarb, and is poisonous. It is not a strong acid, but is one of the few that will remove rust stains (as will citric. it tends to be the organic acids that will do this).

Copper plating of steel before painting = v poor idea, it will set up a "galvanic couple" with any moisture and speed corrosion of the steel. ammonia will clean the copper off. Alternatively, de greasing and boiling in phosphating bath, then washing in clean water is an excellent base for painting.

In general, you will get worse skin burns (eye burns do not bear contemplating) from the strong alkalis such as sodium hydroxide, than you will from most of the acids. Phosphoric and citric acids are probably the least dangerous and un pleasant.

[Myford Matt]

Thanks Noddy - very useful info. I had heard bad things about HF, but never knew it was dangerous on an almost Hollywood scale. Sounds terrifying. Hot water followed by citric acid seems to be a good way to go. Would a chemist be the place to buy it? How is it supplied and used?

Many thanks

MM

[Deleted]

I mentioned somewhere else on this forum about the dangers of handling Viton 'O' rings that have been burnt: They decompose into Hydrofluoric acid among other things!
I can vouch for the danger of nitric acid; In a previous career I was in the Merchant Navy. We once carried 5 gallon drums of the stuff on deck and one sprang a leak, it dripped onto the lap joint between 2 deck plates (about 2" thick) and had made a nice smooth hole all the way through, big enough to put your finger in!The wooden dunnage it was stood on had turned to a sort of paste, eek!

[abby]

Noddy , I must tell you of a pickle used in the aerospace industry , probably elsewhere too , It is comprised of hydroflouric acid and ferric sulphate liquor and is used hot, the strange thing is that although it cleans the metal ,even removing enamel from heat treatment protection, it is bland enough not to harm exposed skin.
Hydroflouric acid mixed with conc sulphuric acid is used for polishing lead crystal glass after cutting.
Abby.

[havoc]

...ferric sulphate liquor...

Hips...is that potable? Fill tham up barkeeper...

[Laurie_B]

usra said:

I mentioned somewhere else on this forum about the dangers of handling Viton 'O' rings that have been burnt: They decompose into Hydrofluoric acid among other things!

As well as Viton,the same problem can arise with PTFE if it is overheated.It can also degrade and form hydroflouric acid,amongst other toxic substances.
When I worked in the electricity supply industry,the G.E.C. company issued safety notices regarding the dangers of PTFE seals (typically used in generator insulation bushes) as one of their personnel had actually died after coming into contact with hydroflouric acid on his skin when working with PTFE seals that had been exposed to high temperature.I seem to recall G.E.C. commenting that there is no medical intervention against hydrofluoric acid poisoning.

[Myford Matt]

PTFE, Viton... ? Let's stick mild steel and brass!

[ericcee]

These "war stories" could go on ...
My first job on leaving school was in the labs of a steelworks (wet chemistry in those days). We used HF to dissolve slag for analysis - boiling it on a hotplate in Pyrex flasks that only lasted a day or two. The senior chemists put the wind up us with HF horror stories, so I guess we treated it with rather more respect than the other reagents. Nitric acid would turn skin brown (like niccotine stains) which would then peel off a day or two later. I had to boil benzene when I worked at the coke-works, where I also handled industrial strength sulphuric acid - that was horrible despite the (crude) protective gear we used.

Perhaps today's elfin safetee rules make more sense than we give them credit for.

[SteveW]

Guys,

I've heard there is an antidote to HF acid. It's quite expensive and has a limited shelf life. There was a discussion about this stuff on the email version of the proboards a load of years ago.

[Chris Kelland]

Hi All,

I buy my citric acid on line from the Home Brew Shop. £4.00 a kilo inc vat but not postage.

[Boadicea]

Guys,

I've heard there is an antidote to HF acid. It's quite expensive and has a limited shelf life. There was a discussion about this stuff on the email version of the proboards a load of years ago.

Steve, it is called HF antidote Gel and has a life of approx 1 year. It is in this list which also gives some interesting information on hf burns....

www.sellesmedical.co.uk/acatalog/Burn_Care_Kits.html

However, you have to act immediately and sometimes you may not know the cause of the burn and, as someone else said, by the time you realise you have been burned it may be too late.

Regards, Bo.

[Noddy]

The stuff for HF contamination is a cream containing calcium borogluconate, the stuff contains about 40% calcium, and the idea is that it reacts to give calcium fluoride. this is ok as long as the fluoride ions have not already diffused through your skin.

Calcium borogluconate is (this might have changed since defra now employ 14 bureaucrats administering agriculture for every 1 farmer) available from agricultural chemists, to inject stock suffering from the "staggers" (hypocalcaemia). In that use it works as a miracle cure, injected into the abdominal membrane, the critters go from death's door to getting up and running away in seconds.

Easiest way is not to touch HF. Unless you are needing to dissolve silica, there are alternatives, and for that 1 use, it is safer to entrust to someone else.

For people interested in the toxicology of Fluorides, "Assimov on Chemistry" has a chapter titled "Death in the Laboratory" discussing the chemistry of fluorine. Apparently one of the first to put sulphuric acid onto fluorspar (calcium fluoride) and make HF, was a Frenchman who habitually tasted all that he made (his name escapes me after 25+ years), like many of the other pioneers in the study of fluorides, he was dead within the year.

A place I was looking at in South Africa, the spring water supply had such high fluorides that the locals' teeth dropped out by their early 20's

Around Stewartby in Bedfordshire and some other brick works, the local dairy cattle used to end up crippled with fluorosis attacking their bones, with fallout from the brick kilns landing on their pastures.

As an aside, we are taught at school that sulphuric acid will displace all other acids from their salts, e.g. boil with sodium chloride to get HCl...

in the barium carbonate veins (witherite veins) in Northern England, the carbonate had, insitu, replaced barium sulphate....

Think on....

Barium carbonate is an astonishing poison, being insoluble, it is tasteless, but reacts with stomach acid to give the soluble chloride....

It used to be used locally as rat poison, and appart from the use in case hardening mixes (the carbonate decomposes at the right temperature releasing CO2 to react with the charcoal or coke, giving CO), was used to treat boiler water to precipetate the gypsum before it got to the boiler to cause scale.

In the Southmoor witherite workings (actually between Lanchester and Burnhope, and pretty much under the road between the two), dedicated tubs were used to carry horse fodder, after the ponies were poisoned, and on the old Settlingstones mine site, the hunt kennels hose down any hounds that go for a run before they can lick their paws.

The toxicology in humans was studied when some muppet in Israel used BaCO3 instead of potato starch in turkey sausages.

Apparently if you survive for 24 hours, you get better, and about 4 grams is the LD50 (50:50 chance of killing you) for a human. Apparently it is a nerve toxin, very like deadly nightshade in its' effects, and hideously painful.
Antidode: a good dose of salts (MgSO4)

before thoughts of the neigbour's verminous cat come to mind, it may have been ideal during Victoria's reign... but one X-ray and the "barium meal" will be obvious.

Chemistry lessons teach us that Barium Sulphate is insoluble.... In the presence of HCl in the stomach, a medical barium meal (BaSO4) is not very far off being soluble enough to cause harm.

Ericee, was the steel works by any chance on that windy hilltop where all turned pink? (and where now the youngsters can be seen turning blue in short sleeves & miniskirts queing to get into the clubs as the sleet comes horizontal at 800 feet above sea level on a january night)?

[Myford Matt]

keithanderson said:

Apparently one of the first to put sulphuric acid onto fluorspar (calcium fluoride) and make HF, was a Frenchman who habitually tasted all that he made (his name escapes me after 25+ years), like many of the other pioneers in the study of fluorides, he was dead within the year.

Good grief, how did he survive his first day in a lab, let alone have a career?

[Noddy]

ps I should say that the dangerous part of HF is the fluoride content. The acid part is relatively innocuous. F- is such a strong ion that the H+ does not readily escape to make acid. It is therefore a "weak" acid, and probably only manages a pH of about 3.5, simillar to vinegar, yogurt, or for that matter the stream water coming off peat moorland in a dry summer (I think certain ladies' hygeine products are also at pH3.5)

Acid burns are therefore unlikely to alert you to any problem.

As with all salts of weak acids and strong alkalis, Sodium fluoride is strongly alkaline (i think around ph12), and has many of the properties of the acid, such as attacking silica and being very poisonous.