Acid!

[Kevan]

Hi! I am trying to set up facilities for silver soldering small boiler fittings. I am a bit stumped trying to find a source of sulphuric acid locally in Edinburgh. How do you all get hold of acid for pickle baths and if not sulphuric what do you use?

Thanks Kevan

[cplmickey]

Hi Kevan,
I was lucky and got hold of a gallon recently from a private seller recently. I must admit I thought it was still fairly easy to get it from hardware shops and the like although it may be marketed as drain cleaner but it's the same stuff really (check the label).
I've also bought some citric acid crystals for pickling after seeing a discussion on this forum but I haven't yet used it. I believe it is effective but takes much longer to work. My crystals came from ebay but home brew shops are also a possible source.
Ian

[uuu]

Citric acid is much nicer than sulphuric. It's available from home brew shops. Probably cheaper online. It's not nearly as dangerous to prepare, store and use, and can be disposed of down the drain. It's effective, too.

Wilf

[92220]

Hi Kevin.

Sulphuric acid is easy to buy, from builders merchants. It is sold as a drain cleaner called 'One Shot', and it is 91% strength. So VERY hazardous, in it's neat condition! It can be diluted by adding it to water to between 15% and 20% by weight, for pickling (not onions!). I'm probably telling you something you already know, but NEVER add water to acid. It will boil and spurt up in your face. Always add the acid to the water. An alternative source is any company that makes and/or fills car batteries. Their standard acid is around 12% to 15% strength, and is often used for pickling.

Bob.

EDIT:  Another possibility is just to boil the silversoldered fittings in water. When I was an apprentice (many many years ago) we had a small stainless steel tank with a small immersion heater in the bottom, in which we used to boil all small silversoldered parts for around 15 minutes. They used to come out completly clear of flux and any other crud. I have a cheap stainless steel bowl and a cheap induction plate for boiling all my jointed parts. Works well but i use it in the garage rather than the workshop to prevent steam and water vapour getting anywhere near tools and the loco.

[timb]

Hi Kevan to echo 92220 with one shot.

I got mine next day from Fullis - no association just a happy customer.

www.fulcare.co.uk/one-shot-drain-cleaner-1ltr.html

Tim

[houstonceng]

Buying Sulphuric acid over 15% without a permit is illegal in the EU and UK. It is also illegal to own it without an EPP Licence and anyone who supplies it to someone who does not have a permit can, also, be prosecuted. H2SO4 along with other oxidants can be used to make bombs, that’s why you need the permit. Of course, the Gov. charge about £39.00 for a permit that has to be renewed every 3 years at a similar cost - so it’s another stealth tax.

You can buy it, without the EPP requirement, if it is less than 15% by weight, so I suspect that drain cleaner available without an EPP licence is now dilute.

[92220]

Andy is right, but I didn't know the regs had changed under the Poisons Act, in 2018. Oopps!!! One Shot is 91% according to the box, and I bought mine from Jewsons about 3 years ago. This is from the government website:-

Since 1 July 2018, under changes to the Poisons Act, members of the public wishing to import, acquire or use sulphuric acid above 15% have required a Home Office licence. ... Professional users do not need a licence providing they are using sulphuric acid for the purposes connected with their trade or business. www.gov.uk.

Jewsons and other builders merchants will assume you are a 'professional user' as they are trade suppliers. Andy is probably right that you, could be prosecuted for buying anything over 15% strength unless you are in a trade that uses sulphuric. It is crazy, but a supplier would probably not be liable because anyone in a trade, doesn't need a licence to buy it, so they assume you are 'trade'.

However, there are lots of places on the 'net that are advertising sulphuric but don't mention a licence being necessary. They probably don't even know the regs have changed!! There are a number of places offering battery acid at 15% strength which is ample for pickling, and is outside the requirement for a licence. It can still be diluted even further, to make it go further too...just takes longer to work. Adding it to the same amount of water (not the other way around!), making it 7.1/2% strength will still work too.

Bob.

[92220]

I've just found, what may be a very handy alternative to sulphuric acid.....Sulphamic acid. This is what the 'net says about it's uses:-

Sulphamic acid is used as an acidic cleaning agent, typically for metals and ceramics. It is a replacement for hydrochloric acid for the removal of rust. In households, it is often found as a descaling agent in detergents, cleaners and toilet cleaners for the removal of limescale.

It isn't regulated and is much safer than any of the acids often used for cleaning.....and it gets rid of rust!! I also found this:-

How to use Sulphamic Acid for cleaning & descaling: For removing excess grout from tiling or dissolving efflorescence from walls, floors etc: Make up a solution of sulphamic acid by dissolving 80-100g per litre of warm water. Apply to surface using a cloth or brush and allow to work for a few minutes. Wear rubber gloves for safety.

Bob.

[houstonceng]

Aug 23, 2020 8:12:43 GMT 92220 said:

Andy is right, but I didn't know the regs had changed under the Poisons Act, in 2018. Oopps!!! One Shot is 91% according to the box, and I bought mine from Jewsons about 3 years ago. This is from the government website:-

Since 1 July 2018, under changes to the Poisons Act, members of the public wishing to import, acquire or use sulphuric acid above 15% have required a Home Office licence. ... Professional users do not need a licence providing they are using sulphuric acid for the purposes connected with their trade or business. www.gov.uk.

Jewsons and other builders merchants will assume you are a 'professional user' as they are trade suppliers. Andy is probably right that you, could be prosecuted for buying anything over 15% strength unless you are in a trade that uses sulphuric. It is crazy, but a supplier would probably not be liable because anyone in a trade, doesn't need a licence to buy it, so they assume you are 'trade'.

However, there are lots of places on the 'net that are advertising sulphuric but don't mention a licence being necessary. They probably don't even know the regs have changed!! There are a number of places offering battery acid at 15% strength which is ample for pickling, and is outside the requirement for a licence. It can still be diluted even further, to make it go further too...just takes longer to work. Adding it to the same amount of water (not the other way around!), making it 7.1/2% strength will still work too.

Bob.

The legislation also says it is illegal to own it without an EPP licence, so if Jewsons sells you done and you cannot show that you are entitled to store it you can be fined or imprisoned

[92220]

Correct. But they don't tell you what to do if you bought it before the regs came in. The Home Office would also have to know that you actually have it before they can do anything about it. They would also have to know, and prove, that it hasn't already been diluted to below 15%. It's a mine field!!

Interestingly, I bought a 5 litre can of janatorial cleaning fluid about 10 years ago and when it arrived it was 90% hydrochloric acid which was a bit of a shock, yet it didn't say anything about that in the Company website, just that it contained hydrochloric acid, and I bought it as a private individual, for derusting steel. It worked brilliantly, though I did dilute it to 50%.

Bob.

[houstonceng]

92220
Yes. Exactly as you have identified, however, as the legislation doesn’t have any grandfathering and ignorance of the law is no excuse, anyone caught with some undiluted acid on the EPP list would be prosecuted. These days, anything that looks remotely like terrorist activity would be jumped on hard, just to increase the positive crime solution stats.

Some suppliers actually state that OneShot drain cleaner will only be supplied to holders of an EPP licence and over 18 - others, such as Selco don’t. Theoretically, if it is a trade only supplier, like Selco, you have to be trade to shop there, so the EPP licence, which applies to private individuals, may not be necessary.

[Neale]

Personally, for the relatively small bits I've been doing recently (i.e. not boiler size!), I have been using citric acid in an ultrasonic bath. That lets me heat the pickle solution in advance, and 30mins of ultrasonic agitation seems to do the job. For bits that don't fit the ultrasonic bath, they get left in the pickle overnight and then given a scrub under running water with a nail brush (or whatever fits the shapes concerned). I also use citric acid solution for pickling steel parts after silver-soldering and that seems to work fine - leaves a dull grey finish that seems to take primer OK. I do keep separate solutions for steel and copper.

[Jo]

Aug 23, 2020 8:46:55 GMT houstonceng said:

The legislation also says it is illegal to own it without an EPP licence, so if Jewsons sells you done and you cannot show that you are entitled to store it you can be fined or imprisoned

The police have got better things to do than going round people's garages to see if they have illegally held chemicals, unless they are suspected of being a terrorist.

Instead I would like to see them chasing up on compliance with the 14 day quarantine for people returning from certain countries. Like my neighbours who arrived back from Portugal two weeks ago and spent the following week driving up and down 30 miles to their yacht every day, then having people visiting them at home in the evenings .. Its a total farce .

Jo

[millman]

Totally in agreement with you Jo.

[Tony K]

Meanwhile, drain cleaner is not 91% concentrated sulphuric acid - what it says on the tin is misleading.
It is 91% sulphuric acid of unknown concentration - which I have found to be about 30% at best.
I found this by comparing to the real thing.
Still hazardous though.

[springcrocus]

Wilf and I built a 5" gauge Britannia boiler using citric acid as the pickle. 5 kgms of THIS dissolved in twenty gallons of water was enough to immerse the whole boiler. Copper goes a nice pink colour in an hour or so, and it also removes most fluxes. Steel will gain a pink patina after a while, as I found when using it to remove galvanising.

It's clean and safe. Why risk using something that is far more dangerous? Splash yourself with sulphuric and you will need to find a cold water tap PDQ, citric acid you can just wipe off.

Regards, Steve

[Neale]

I suspect that the pink patina left on steel is deposited copper from the pickle solution. Whether it is a problem or not later will depend on how well it adheres to the steel, I guess. That's why I keep separate pickle for steel and copper. Might be more problematic with iron contamination of the copper surface, although that is less likely to happen.

Remembering back to chemistry lessons from rather a long time ago, I think that where there is a metal compound in solution (in this case, copper citrate in small quantities) which comes in contact with a more reactive metal (iron), the less reactive metal is displaced by the more reactive and comes out of solution, leaving you with iron citrate and deposited copper.

[JonL]

I use Citric and its been fine for me. I keep it in a cheap plastic kettle I purchased for that purpose.

[millman]

I have used citric acid for many years for copper and brass components and am perfectly satisfied with it, however I use brick cleaner, available from most builders merchants for pickling steel fabrications as it is far better at removing the black crud, works in about an hour and parts come out a dull grey colour, don’t know what’s in it as I keep it outside the workshop and the sun and rain have made the label unreadable.

[coniston]

Aug 26, 2020 15:07:57 GMT millman said:

I have used citric acid for many years for copper and brass components and am perfectly satisfied with it, however I use brick cleaner, available from most builders merchants for pickling steel fabrications as it is far better at removing the black crud, works in about an hour and parts come out a dull grey colour, don’t know what’s in it as I keep it outside the workshop and the sun and rain have made the label unreadable.

Brick and concrete cleaner has a high percentage of Phosphoric Acid which as you have found out is excellent for pickling steel/iron including rust removal with the added benefit that it gives a phosphate coating which helps prevent rust forming again. An alternative to Phosphoric Acid for steel is Hydrochloric Acid, very dangerous stuff but diluted to 10% is excellent for rust removal, it is what is used in steel mills for removing scale from hot rolled steel products.

Chris D