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Witches brew for pro chemical removal of zinc plating

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AshimotoK0:
Update on this.  I was prepping some parts for zinc plating at the weekend  and thought I would try the stripper in my heated ultrasonic bath and it worked really well, so recommended if you have one but it must be heated (I guess mine was at about 65 degrees C).  I put the parts into a container and covered with the stripping solution and  then put into my US bath with the heated tap water in it.

When I take the parts out I rinse them really well in cold water then put them after draining into a plastic bucket then pour boiling water on them. After a few seconds, I then drain through a sieve and spread out on loads of kitchen roll, then after drying for a few seconds  but still really hot, I  tip them off the damp kitchen rolll onto a flat surface. Doing this, the water totally flashes off and they don't then flash rust.

A few peopl have asked me why not use hydrochloric acid? The chemist guy I worked in the 1980'/90's with, recommended my witches brew  because it is much gentler on the steel base material. I also got his from one of the pro-plating forums. Also hydrochloric acid is bad news in your shed garage as the fumes from it will promote rusting of everything around it.



"2004
A. We use HCl to strip zinc from steel. You can use sodium hydroxide too. Why use power when it's unnecessary?

Steve Clark
- Belfast, Maine, U.S.A.

2004
A. Acid stripping is bad news for hard bolts. Hydrogen embrittlement is a very strong possibility. Bake (soon) after strip if you do. Caustic is slower than acid, but it also has a lot smaller risk or attacking the steel. Electrolytic will speed up the operation, but costs more-- a tradeoff.

James Watts
- Navarre, Florida"

Oggie400F:
Great Info Ash
Thanks. 👍

kettle738:

Really interesting stuff, thanks Ash..... I used to have a local plater (chrome and Zinc) who had a rotating drum for zinc plating small parts....they didn't need to be wired and they self 'burnished' as they tumbled.....the results were superb.... and quick.  This was a bloke who would recreate linishing marks in the chrome on Jap rims....every other plater I've ever met only wants to do the bathroom tap finish.

Sadly.....he closed down and the only remaining local plater which is a far larger outfit does everything by hand, each part including spoke nipples, tiny nuts etc is wired, it must take forever, I can't understand why a business would continue to use such an archaic method for small parts.....I always prep them, so I'll try your method for my next batch.   

Nurse Julie:
99% of our zinc Plating is done in a tumbler that holds 50kg. We usually have 25-35 kg done at a time. Very rarely we may have certain parts that are wired for whatever reason, usually due to them being fragile parts.

SteveD CB500K0:
Can you explain the different chrome finishes Mick?

Assumed “bathroom tap” was what you got.


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