Saturday, September 24, 2005

Etching in the acid detail

In the comments below, Byron wonders about detail on the use of citric acid. I'll do my best; that is, it's simply what I did and it probably varies. It all started, as far as I remember, with this information. This was picked up on The Old Tools list, and it sort of grew from there. Just put "citric acid" into The Archive's search under "keyword" and you'll see what I mean... It interested me, and eventually I bought some citric acid to try it. About £1.50 for a little pot from the local Home Hardware - I'm sure there are cheaper places. Put some cold water in the bottom of a cleanish old ice cream box, just enough to cover the tools, spinkled in about, ooo, a heaped tablespoon? And, as I say, a dash of meths and washing-up liquid (Lemon scented, but that's not essential). Gave it a stir and put in the dividers etc.; if you look closely when you do that you can see tiny bubbles appear on the surface of the tool. Make sure the tool for the treatment is grease-free, or it won't work. Guess how I know that - no, not from reading the instructions. Don't be silly... Anyway, I checked them after two hours, then every hour afterwards for the afternoon, before I decided what the hell and left them in overnight. I didn't realise they'd still look the same in the bath regardless of how long they were in, you see. But it was okay and not a disaster. Eventually I thought "this isn't working, stupid thing", fished them out and gave them a scrub with some brown non-woven abrasive (a dish scourer in household terms, Webrax or Scotchbrite in workshop ones!) under the tap in case the acid might do more harm than good. Before my wondering eye the rust and crud just scrubbed off to reveal unto me bare, but slightly dull, metal. Huzzah! How much it dulls, and how long it takes, depends on the concentration I gather. Someone suggested lots of dilute baths might be better to minimise the degree of dullness, while a really concentrated bath might get things done in an hour or two. Whatever, it certainly beats abrasives and white spirit on these finicky tools. I can't recall off-hand what the word was on its effects on paint and japanning, but I have a feeling any loose stuff you can assume you'll lose.

Anyway, that may or may not be of any help, but at least the links with more detail are now recorded in one place when I need them. Oh, and welcome to the Blog, Byron. :~)


  1. Alf, thank you for going into detail and providing some links. Being a newbie to ye-olde tool restoration, something like this will be invaluable in saving time with abrasives (and broken fingers etc..)

  2. Byron, you're most welcome. Definitely follow up some of the stuff on the Old Tools List; some good advice and experience therein.


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