Pickle Strength

[ron]

Hi Everybody
I might have asked this before but can't find the answer so bear with me, I've bought some fresh battery acid to make up a new pickle bath, is there an optimum dilution for pickle? at the moment I've diluted it 50/50 and used it to clean some crusty flux on the tube bundle and it worked well but I could do with a larger volume so I wondered whether to dilute it a bit more or buy more acid.
Ron

[Tel]

Around 10% or so of acid seems to work OK, takes a bit longer is all

[the_viffer]

What kind of acid did you get?

Was it 2M, 33.5% or 98% or something else? 98% is easy to spot as a squirt of it on a bit (I was going to say a well known measure by which you dole out the suger in your tea but it comes out as spoonful) of sugar will let you know that is what you've got. It is not that [/i][/u] dangerous experiment if you are wearing the kind of stuff you'd wear to do some some casting. You'll not be wanting to ask your 4 year old to try it. Oh and it is up there as one of the great experiments if you've got 98% or stronger.

1M is more than strong enough I think. If you've got 2M add to about an equal volume of water with stirring. If it is 33.5% then adding to about 4 times the volume of water should do the trick.

If it is stabilised sulphuric lob it down the heads with loads of water (stabilised sulphuric is sold as drain cleaner so don't get all green on me. It is has been a harrassing day, OK?) since it has a nasty habit of rotting silver solder joints as a well known ME found to his cost...

[ron]

Hi Viffer
It's standard fresh battery acid which is about 35%, I would be surprised if conc Sulphuric is available to the general public, in fact having worked in ICI's T7 sulphuric acid plant years ago I hope not, it's nasty stuff.
Cheers Tel, I'll add a bit more water.
Ron

[the_viffer]

Ron

98+% sulphuric is readily available in the UK. We have some under th esink for cleaning the drains It was easier to buy it than have my wife swipe some from her work.

The cost was GBP8.93 for 3 litres inc VAT.

[ron]

Viffer, are you sure it's 98%? that's more likely to dissolve the drains than clean them, it even dissolves concrete in minutes, and anything over 100% is oleum which is one of the nastiest chemicals I've come across, you can't even wash it off, it just keeps burning in. Most drain cleaners are nearer 10% than 98.
Ron

[the_viffer]

Actually it is 96%, Ron, www.hswalsh.com/itemdetail.aspx?i=T97012&c=527 . It doesn't dissolve concrete that much as the first lot turns it into calcium sulphate which is resistant to further attack.

You can even buy hydrofluoric acid off the retail shelf in the UK. I've done some mighty crazy stuff with chemicals in my time (I was trained as a research chemist) but HF is one of the few chemicals I've never handled and don't plan on starting now.

[baggo]

I get mine (98%) from Lab Chemicals International Ltd. (Usual disclaimer)

www.thechemicalshop.com/

More expensive than T-V's though at £13.99 for 500ml plus delivery.

John

[ron]

Viffer, it attacked the concrete so badly it led to the plant being shut down in the 70s due to the concrete foundations dissolving, even the kerb stones on the road round it dissolved, all that was left was the aggregate! The strongest Sulphuric we manufactured was 98%, we strengthened 60% Nitric to 96% but Sulphuric was 98%, 96 must be for lab use rather than industrial.
I find it a bit annoying paying OTT money for stuff we used to ship out in 20 ton tankers.
John, do you aim for a particular strength, or does any strength dilute Sulphuric do, I'm trying to fing out if there's an optimum.
Ron

[baggo]

Ron,

I dilute it about 1 in 20, mainly to make it go as far as possible ;D I find that it works well enough. After completing a major assembly I leave the boiler or whatever in overnight and it's nice and clean after that.
One word of caution, keep steel well away from the bath. I made the mistake once of leaving a steel clamp on a firebox/tube assembly when I pickled it and everything, even the silver solder, came out copper plated!

John

[chris vine]

Hi Ron,

Being a bit of a Scot (well mostly adopted really) I am told that water works quite well on the sort of fluxes we use. It just takes longer.

It might be useful for something large like a boiler when it is cheap enough to fill up a dustbin.

I may be wrongly informed so now is your chance for some experimental work and tell us the TRUTH!!

A fantastic day here for a change, I spent almost all of it out side, cutting up wood for the fire. There is plenty of it about in the village after the storms. I guess you can use an ex-Gazebo or Pergola, I forget which. I am waiting for the rest of the group to complain about our weather exchanges..........

Chris.

[ron]

Hi Chris, I've sent you a message.
Weather to go downhill again on Thursday, B&Q have run out of roofing felt, clootie nails and fence posts. ;D
Ron

[alanstepney]

For details of flux's and the best methid of removal, plus much more on silver soldering,

www.jm-metaljoining.com/shared/frameset.htm

I use anything from 5% to 20% solution of Sulphuric acid, but acetic acid works too, albeit more slowly.

[paul]

Vinegar works (slowly) and has the advantage that you get to eat all the onions to free up the liquid whereas anything pickled in sulphuric tastes 'orrible

[abby]

A boiling solution of citric acid is very good too for flux removal but I find the best way for small parts is to drop them into some water whilst still hot and the flux dissolves immediately!
Abby.

[teakfreak]

Citric acid works well too, doesn't smell as bad as acetic acid and is safer if you have small children anywhere near your workshop (I know that they shouldn't be allowed near but they don't know the meaning of of fear and have insatiable curiosity. I tend to use around 10-20g/L , but Ithink Tubal Cain once wrote that most silver solder fluxes are more soluble in alkali, so a mild (5-10% solution of caustic soda might be better.

[Shawki Shlemon]

Hi ron
I use battery acid and is 35% strong and then I diluted 2 water to 1 acid to bring it to approximately 10 % as tel says .Remember always pour acid on water and slowly .Good luck

[Jo]

T-V: I do not like the look of having 3 litres of 96% in a plastic container!

My thick glass carboy of 98+% proof lives in its original polystyrene casing and only comes out to refresh the pickle tank, as and only when necessary. The rest of the time is is seriously respected and left tucked in the furthest corner where it cannot be got at.

I've tried critic: Nasty green scum forms in about a week so you seem to be forever replacing the stuff. Using Vinegar puts me off chips for days. I do not know what pickling copper in it does but it changes the smell.

Jo

[the_viffer]

jo said:

T-V: I do not like the look of having 3 litres of 96% in a plastic container!

My thick glass carboy of 98+% proof lives in its original polystyrene casing and only comes out to refresh the pickle tank, as and only when necessary. The rest of the time is is seriously respected and left tucked in the furthest corner where it cannot be got at.

I've tried critic: Nasty green scum forms in about a week so you seem to be forever replacing the stuff. Using Vinegar puts me off chips for days. I do not know what pickling copper in it does but it changes the smell.

Jo

Jo you are right it is a frightening thought to have sulphuric in a plastic bottle. Ours lives in a labelled "Winchester" (which is not an old disk drive but a brown glass 2.5 litre reagent bottle) which is stored in a bund.

Reminds me of my first day as a post-grad. My boss showed me round the lab and when we came to the solvent bunds he started raking around pulling Winchesters out. He showed me the absolute alcohol. "Don't drink that" he said "it'll make you go blind". He raked around some more and then showed me some 96.3% alcohol. "Drink that instead," he said "it doesn't have any benzene in it."

You can make vinegar more effective by adding salt to it. Works with chips as well. I would expect that it'd also make citric more effective.

Another one worth trying for copper based stuff is a mixture of meths and 880 ammonia. It is astonishingly good for cleaning out one's tubes. Certainly one for outside. You need to be wary with some kinds of brass as it can induce stress cracking but the kind of brass the horologists (I was so disappointed when I found out that was the study of clocks) use is fine.

[ron]

I must admit I'm very surprised at the ease with which conc sulphuric is available to the general public in the current nanny state, I never even thought of trying to buy it, even 30 years ago the PPE to enter an acid plant was full PVC suit, goggles AND a visor, rubber boots, helmet and gauntlets, that wasn't to do intrusive work, just to be on the plant.
Ron