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Thread: Pitting after firescoff

  1. #1
    Join Date
    Apr 2021
    Location
    Switzerland
    Posts
    7

    Default Pitting after firescoff

    Hello everyone,

    I've just taken up some occasional jewellery work again after visiting a course a couple of years ago and thought I'd go with firescoff when I was getting my supplies together as it seemed worth a try for my occasional use.

    I realise that the product gets mixed reviews by many people, but I've ran into an issue that no one seems to have mentioned yet:

    Whilst part of the coating it creates can be washed off with warm water as advertised about 40% of it can barely be removed, and when it is removed the silver (sterling) is deeply pitted - deep enough that it can't be buffed out but needs to be sanded. (and the soldered piece removed to be able to sand it and the piece engraved again)

    Has anyone ever had the same problems?
    Any tips I can try?

    I've attached an image that hopefully is somewhat helpful in illustrating my problem. I sadly forgot to take one of the coating removed and the pitting showing. It's basically there where there are 'bubbles'/grooves.

    Click image for larger version. 

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    Cheers,
    Geoffrey

  2. #2
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    8,238

    Default

    The best way to avoid firescale is to avoid intense hot spots, by reducing the air to your torch, keeping it moving and working in a darkened area so that you can see an even dull red.

    If you want to apply an anti firescale flux, use boracic/boric acid powder dissolved in alcohol. It can be used as a dip, or painted on a warmed piece. The alcohol can be left to evaporate, or burned off. The resulting white coating is the protection. It will never cause damage to your work
    Keep your bottle, or dish well away from the flame. Dennis.

  3. #3
    Join Date
    Dec 2014
    Location
    South Australia
    Posts
    1,496

    Default

    I can't comment on the firescoff as I have never used it, don't think it should have that result, although I do recommend and use Boric acid as Dennis recommended.

  4. #4
    Join Date
    Apr 2021
    Location
    Switzerland
    Posts
    7

    Default

    Boric acid can't be bought by the public here as far as I'm aware, that's why I thought I'd give the firescoff a try.
    I'm using a fairly simple butane torch, so reducing the air probably isn't possible. I could give another one I've got lying around a try or get softer solder I suppose.

    I must say, it confused me a lot because I had been playing around with the solder beforehand on a scrap piece without the firescoff and didn't get any firescale at all, just discolouration as expected.

  5. #5
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    8,238

    Default

    Boric acid powder can be bought from a variety of sources, including online, groceries, garden supplies and pharmacies. It's just a matter of the cheapest source.
    You don't disclose where you are, BTW.

    An oxidising flame can be modified by closing the air hole slightly, if necessary by making an Ω shaped clip from copper or brass strip to slide over it.

  6. #6
    Join Date
    Apr 2021
    Location
    Switzerland
    Posts
    7

    Default

    Sorry, I'm in Switzerland.

    I'll get experimenting a little with scraps again - I thought I had the hang of it at one point!
    I also fear that I have got a tad too many different projects going at once!

    Thanks!

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