Sulphuric Acid for anodising

Edited By DMB on 13/06/2016 16:16:52

I have used the one shot drain cleaner with no issues. Off the shelf at B&Q or Wilkinsons.

Yep the purple dye is added to prevent you thinking its water and drinking it. Not had to match a colour exactly though. I know not to use stainless screws even if they are out of the liquid. My bracket moved slightly and it touched the acid and got eaten away.

My Dad told me a little rhyme from his schooldays, Something like.

Little Jonny is no more he drank what he thought was H2O but it was H2S04.

Caustic soda isn't used for anodising, sometimes etching prior to anodising.

Nitric acid solution is used as desmut.

Who advertise on ebay **LINK**

though I got mine, for electro/acid sharpening files from South Yorkshire Battery Services

Correct. The workshop practice series on it is pretty good BUT the current density mentioned can be way out so best try a bit first. I used lead flashing for the anode ?? cathode and cleaned it up with white vinegar - acetic acid etches it.

John

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Dylon dyes work after anodising I believe and you have to subject the coloured part to a steam treatment to "fix" the dye.

Pure Ali works best, alloys will vary the colour so do not mix you metals for the best cosmetic effect. If you have a part "black hard anodised" the dimensions increase slightly.

Holding devices should be made of Titanium for anodising. Clip or hold where the marks cannot be seen.

All work is done hot and with clean rinse between baths. I have known coloured inks to be used for colour work.

maybe it's a matter of suck it and see as some colours are no good. Again due to type of Alu. HE30 and HE15 seem OK. Cast not so good as even black will not take up very well.

Clive

Have you you got a link to this?

**LINK**

I found the current levels suggested were too high but that could be down to size and the aluminium I used. I used quink for dying so any colour of that should be ok. Some dyes don't work so it's safer to buy the correct thing. They were listed on ebay.

I simply suspended the part on aluminium mig wire. Small part tube like over an inch bore, thin and 1 + long. It was something to finish off a fishing rod tidily.

To get the correct current levels I just used a scrap bit of 10mm dia aluminium rod that was lying about.

John

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Edited By Ajohnw on 13/06/2016 18:13:11

Dave Smith the 16th -

Johnny was a nice young lad but now he is no more,

For what he thought was H2O was H2SO4.

As taught to me by my father!

George

I thought caustic soda had a violent reaction with aluminium or is that just Dural because of the copper content. I think some of the drain cleaners will be HCl like the patio cleaner even more diluted as that also gets sold as a loo cleaner. Check the label. Perhaps someone with the pink version for pickling could try a scrap and see if it does stain.

Amazon!

**LINK**

You can you either lead, low alloy aluminium (6061, 6063) or titanium for the cathode.

Dyes are so cheap you might as well use anodising dyes, the others are just hassle if they work at all.

The work piece is held with either titanium or aluminium.

6061 & 6063 anodise the easiest / brightest, followed closely by 6082. 7075 is a bit more difficult to get a very bright finish, although the way it anodises it tends to hide small scratches etc.

Just seen this, thanks.

Yes, you can work out current density from anodising a piece of aluminium with a known surface area!

Yes, it dissolves it. It's used for stripping anodising from aluminium and for etching it prior to anodising.

Stainless steel will dissolve in sulphuric acid whether it has electricity flowing through it or not, it gives of some very nasty fumes.

Steel / magnesium will also dissolve.

I think I wrote this in another -earlier - thread about anodising, so I keep it short.

Here, Sulfuric acid (concentrated) is available in shops called Drogerie; according to my translator this might be chemist or drugstore. Similar to a pharmacy, but without prescription medication.

In shops of the do-it-yourself type, department for swimming pools, there are products for lowering the pH of the water, Here again, pH- liquid is sufluric acid of around 12 +/- 2 %.There is also a cristalline pH-, Sodium hydrogene sulfate (NaHSO4), which is also suitable for anodising. The Na ions don't do any harm...

As an aside, inkjet printer ink is suitable for colouring. Be prudent with the Dylon dyes, there is only one type suitable. Don't ask how I know, what I bought was totally crap for that purpose.

Regards, HansR.

In the UK anything stronger than vinegar and its like ordering stuff to make nuclear weapons. If it was not an essential ingredient in batteries it would probably be banned.

Shocked to find drain cleaner with it in a strong solution. I only found that out after reading someone complain that it was on the bottom shelves next to the till with sweets on the next shelf.

It was a what if the bottle leaked and the bag its inside also leaked and ...... The sort of person that would ban all your home workshop stuff instantly and would faint if they knew i tought the kids to shoot air rifles in the back garden.

Some of the more dangerous chemicals are now only allowed to be sold to limited companies. Even attempting to purchase them is an offence!

I don't like sulphuric being used in drain cleaner as people also use bleach in sinks etc, it's a very bad combination! Having said that I've never heard of any incidents.

My wife followed instructions to make some 'slime' for the kids from the Internet, having looked at what she was using, the chemical "causes skin burns and serious damage to eyes" nice.

Tried anything and everything what could get my mittens on, still got the Quink and fabric dyes no substitute for the real thing which went off 11 years ago sold by a place over Leicester.

Must have been lucky just drove up to a local chemical suppliers asked what needed then went back following week after they got to know me, no names and walked out with 25ltrs Sulphuric, 50ltrs distilled water, 10 ltrs hydrochloric acid £30.

Very true sulphuric at 17% will rot thin steels away within two weeks, don't ask had a leak from a 4ft tank but still got the little 12".

Back 15/16 yrs not much info available only three sources in the world and what was told was porkies or something blatant omitted.
Used to run anodising at 21% initially then dropped to 19% then 17% both at 13.6V. Even done hard anodising. Just a slight tingle retrieving parts that's dropped off at 21%, rinse off with water.
Sooner pay for it to be done since eventually found an anodisers that cares, can match up with existing even different aluminiums and finishes sent in. Usually send in two colours a month last 10yrs after 6 years diy then prior 6 yrs pro again. Only reason started diy anodising was of poor service, lost hand made one off parts, not ready when said would be, scrap parts quite often certainly the ones in Brum borderline scrapped three jobs £11k.

Just law to themselves anodisers, caused me serious grief over the years, excluding above when it don't come out right precision parts stripped once, twice, three times? who knows so when put threaded parts together nothing lines up. One job last year at a Brummy place 1mm pitch thread ended up 290 degrees further round than acceptable = scrap £400, nearly all like that from experience. If job done right first time with no or little cleaning anodising adds to any surface, more so hard anodise and forget the depth and surface build up off hand.

One of the pros use does stuff for a prestige major car producers, they do use titanium for jigging the parts usually spring clips of some sort o individual racks dunked in to the sulphuric black with use.

Never ever had any success using aluminium wire, fine at first then just lose electrical contact often within 3 mins. Used to use 6082 filed up tapers and wedge in a part or titanium wedge in to a hole.