pickling tin?

[jarrick]

Hi all,

I need to dip some tin objects into something to remove all the white/grey corrosion from the surface. I don't have time for scrubbing so I'm after a simple liquid dip I can leave for an amount of time. I read on the net that Hydochloric acid is the stuff to use but there was no mention about concentration or time scales.

I can get 36% Hydochloric acid easily - does anyone know if this will do the job well, how long it might take (roughly) and if it will leave the surface shiny or dull/matt?
Also, any tips on how to neutralise it after would be most appreciated.

Thanks.

[Dennis]

You can only try various dilutions and various times for yourself. I would dilute the acid available with equal amounts of water to begin with and then remove and rinse under running water when clean enough.

For peace of mind you can further neutralise in baking soda or soda crystals.

Health and safety Please be ware that you are using a very corrosive substance. To avoid a violent reaction, always add acid to water, not the reverse. A glass bowl or container is safest: brass tweezers, gloves and eye protection are needed.

The result will be matte and as tin is soft you will have to try a gentle method of finishing. Dennis.

[Goldsmith]

You do not say what the tin object is, one thing to remember is that if the tin object has been soldered anywhere it is likely to be a lead based solder and a hydrochloric acid solution will dissolve the lead solder. One other tip is when I have needed a hydrochloric solution I have purchased Hiltons Spirits of Salts drain cleaner, which is a diluted hydrochloric solution, see; http://www.hiltonbanks.com/hb_household_products.htm , I actually use this solution for removing lead solders from antiques that I restore.

James

[jarrick]

Thanks for the answer Dennis - just mainly wasn't sure if 36% would be strong enough.

Do you know if a bit of ammonia diluted with water would be ok for neutralising - that's what I'm using for zinc chloride flux residues.

[Dennis]

Ammonia is alkaline, but the ammonium chloride formed is an irritant in its own right. Most of us have soda around the workshop and combined with hydrochloric acid you get sodium chloride, which is table salt.

Ultimately the salt formed will need rinsing off with plenty more water. Dennis.

[jarrick]

Just to add a final note to this thread - after dipping the tin in hydrochloric acid, the tin finish was a grey matt colour showing the crystaline structure (not shiny)