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Thread: Diluting Ferric Chloride

  1. #1
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    Default Diluting Ferric Chloride

    Good morning

    For about 6 months I have been experimenting with etching with Ferric Chloride. The results have ranged from outstabding to truly awful. A consistent problem is the appearance of circular unetched areas which vary in size from less than 0.5mm up to 3mm or so in size. I found yesterday that the etchant should be diluted before use. Is that correct and could using the etchant in concentrated form cause the problem?
    Thanks
    Alan

  2. #2
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    You don't say what you are using as a resist Alan, nor how your metal is being de-greased, or for that matter what metal you are etching.

    Obviously Too strong a solution will undermine your resist, so here is some information to start you off:

    https://www.google.com/search?client...sclient=psy-ab

    https://www.google.com/search?client...fPUA_wQ4dUDCAs

    Welcome to the forum, Dennis.

  3. #3
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    Apr 2020
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    Many thanks Dennis much appreciated.

    My apologies for not being clearer. I am using either PVC adhesive tape, self adhesive letters/designs and/or sharpie pens. That though is not the problem because the parts I cover up come out fine and untouched by the etchant. The issue is centred on the metal that is etched and it is here that I either get uneven mottling or quite often circular patches of the dimensions mentioned where the etchant has not touched it. I am scrupulous about preparation and degrease with acetone and wear vinyl disposable gloves during preparation.

    I shall read the information on the link.

    Many thanks again

    Alan

  4. #4
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    One crucial piece of the jigsaw is still missing Alan. What is the metal you are etching?

  5. #5
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    Are you using a static bath or is it agitated.

  6. #6
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    Apr 2020
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    Dennis

    Many thanks again. Just goes to show how much of an amateur I am . I am using copper

    Alan

  7. #7
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    Apr 2020
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    China

    I suspend the copper upside down from polystyrene with double sided tape and just let it float. 40 minutes seems to be about right for a new solution and I have been up to 1 hour when the solution has been used for a while.

    Alan

  8. #8
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    You may want to try the agitated method, I have a very similar problem when a mate was making his own Zinc badges for his machinery, any tiny impurities can settle and form a resist, agitating prevents this
    you will also find that agitation also gives more even etch and will be faster as well

  9. #9
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    [QUOTE=AlanPConroy;107657 I am using copper. Alan[/QUOTE]

    Ha ha, I was hoping you would say silver. Well, if its copper, the the new answers above are probably right. Insoluble particles are setting on your metal to create blank and spotty areas.

    Agitation can be done with a fish tank aerator, but the simplest way is just to float it upside down as already said, by taping a piece of waste polystyrene foam to the back. Dennis.

  10. #10
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    Apr 2020
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    Quote Originally Posted by china View Post
    You may want to try the agitated method, I have a very similar problem when a mate was making his own Zinc badges for his machinery, any tiny impurities can settle and form a resist, agitating prevents this
    you will also find that agitation also gives more even etch and will be faster as well
    Thank you China. I am most grateful and will give that a try this morning.

    Alan

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