Further Adventures in Rust Removal

Continuing from the last post, having tried the gel, I now wanted to compare the Restore solution with my faithful old stand-by, citric acid. So the victims were to be a pair of firm joint inside callipers and a pair of wing compasses or dividers. The firm joint outside callipers were a serious basket case, so I thought I might sling them in my usual hot soup as a sort of control. I also threw in a couple of other items with it, which was just as well as the callipers turned out to be beyond rescue.

In an effort to make it as "workshop scientific" as possible, the guinea pigs were chosen as being both from the same source (the coachbuilder's tools) and in a pretty similar state of despair. Both were given a lick and a promise scrub with some coarse-ish non-woven abrasive to shift the worst of the crud and give both the Restore and the citric acid solution a fighting chance. I also set up identical baths, giving both 15 units of tap water and 4 units of hot water from the kettle, to take the edge off and help dissolve the citric acid powder. 1 unit of Restore was added to one container; approximately a heaped tablespoon (or maybe less) of powdered citric acid was added to the other, with a drop each of methylated spirits and washing-up liquid (one of them breaks any surface tension, the other stops stuff growing in it). Both were thoroughly stirred and the guinea pigs lowered in. The instructions for the Restore liquid specified suspending the rusty object, so that's what I did. Could have done with some thinner wire, but never mind...

A couple of minutes in, and not much to see with the Restore.

The citric acid, however, has the tell-tale bubbles forming all over the tool.

Meanwhile I brewed up my usual citric mix - kettleful of boiling water, dessert spoon of citric, meths and washing-up liquid as before. This is what I call my Hot Soup. Everything just gets tossed in any old how, and as you see, things get exciting on the bubble front straight away.

The Restore instructions suggest a soaking time of an hour, but I was already hauling out the square from the Hot Soup at 20 minutes. Straight out of the mix, it's black and filthy.

A quick scrub under running water to have a look, and you can see it's pretty much done. Just needs polishing up now.

So I did that while I waited for the hour to be up, and then hauled the guinea pigs out of their respective baths. Untouched, the Restore certainly seems to be winning comprehensively.

However, after a brief scrub under running water for both of them (as specified in the instructions), the difference isn't quite such a big deal.

After cleaning up, you'd be hard put to know which had been in which solution. It's not an ideal comparison, because experience has shown that different steels can respond in different ways to citric acid, and I imagine the same probably applies to Restore.

The important thing is it revealed a maker's name on the wing dividers. I read that as J & T Colley & Co, but a cursory search hasn't thrown up anything. But I'm not entirely sure about the first letter being a C...

Anyway, as is the way, when you have Soup on the go, hot or otherwise, you inevitably chuck in a few more things, which I duly did and then polished up a bit. I'd be hard put to tell you which went in which mixture though. Worse than that, I was going to part with at least five of these, and now four of them seem to have crept into the "keep" box...

So, thoughts thus far. In a "rust off" using equal soup temperature conditions, actual speed of rust removal was much the same. The Restore seems to have a bit of an edge in not needing quite so much black coating removed to look okay, which is a bonus if you don't intend to in any way abrade or polish the tool to remove the dead grey look. On the other hand you are still instructed to scrub the item under running water anyway, so...

The instructions suggest dunking it back in the solution if you want to treat it with a protective layer to prevent "flash rusting", but I haven't tried that yet, as I wanted to finish cleaning them up properly. But flash rusting does seem to be more of an issue with Restore than I've ever found it before with any other method; as far as my, so-far, limited experience has shown, the benefit of being able to prevent flash rusting in that manner is less of a bonus and more of a necessity.

For speed, the hot citric acid solution is hard to beat. The Restore instructions suggest that if you have a stainless steel tank you can heat the solution to not more than 50°C to speed things up, but as I have neither stainless steel tank or means to make sure the temp is correct, that's a bit of a moot point. I also suspect the fuss of suspending the tools on wire is pretty unnecessary, and you could just as well flip them over occasionally, as I usually do with the citric acid.

As it stands, given the relative costs of Restore and citric acid, I can't honestly find enough benefit in buying the expensive stuff. But I'll keep playing with it; the re-dunking to prevent flash rusting may be a big help when it comes to the auger bits, and I want to try a couple of sacrificial lambs for a longer bath, to see what the damage is.

Anyway, good news - the measuring and marking box is done, and here's what I think can go. I think. Probably. Fact is there are some rather nice tools in there - I was expecting nothing but dross that I couldn't even give away. Bugger.

Now which class of tool to start on next? (A virtual clip round the ear for anyone who suggests the chisels...)