Citric Acid Pickle

By Anna on May 24, 2007 at 10:32 am

Citric Acid Pickle

We’ve used a citric acid pickle for about 9 months now with great results. Citric acid is a fairly common preservative used for canning foods (i.e. it’s edible). Citric acid is non-toxic, in fact it’s derived from citrus fruits, and it’s relatively cheap and easy to find. It works fine as an alternative to Sparex or other chemicals to remove flux (halide salts used to ease the flow of solder), oxides and firescale after soldering.

Citric acid is much less caustic and tends to last longer than other pickling agents. It can cause eye, skin, and respiratory irritation -so be careful, but we’ve never gotten any burns. The biggest drawbacks are that citric acid has to be heated (as opposed to Sparex, which just works better hot), and it takes at least twice the time to work. There is some debate over the ideal water/citric acid ratio, but we use about 10:1 water to citric acid with good results. Some jewelers say that distilled water works infinitely better than tap, but we haven’t had any issues. It may depend on the mineral make-up of your tap water. You can buy citric acid (the technical name is ‘anhydrous fine granular citric acid’) at wholesale prices from spice & herb or chemical companies, and sometimes at the grocery store with canning supplies.

To dispose of citric acid pickle: neutralize it first with baking soda, and check with local waste management authorities for regulations (down the drain? cat litter?).

This site has art materials disposal info:
http://www.ci.tucson.az.us/arthazards/dispose.html

Citric Acid material safety data sheet:
http://www.jtbaker.com/msds/englishhtml/C4735.htm

More comprehensive Citric Acid Pickle article:
http://www.touchmetal.com/workshop/citricacidpickle.html

Comments (2)

  1. I’ve been expirementing with Nventa’s Firescoff, a heat-activated ceramic spray that in theory obviates the need for boric acid, flux and even pickle (you should be able to just rinse the piece when done). I’ve used in on brass and white gold thus far, and it seems to work pretty well, although it is not ideal for situations where you are trying to control solder movement by previce placement of flux.

  2. Citric Acid pickle works surprisingly well. I get mine at the local (well, not so local) Indian grocery store in Jackson Heights. In my case Distilled Water has made all the difference in the world. My tap water just wasn’t cutting it. I highly recommend picking up a jug just to see the difference.

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