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  1. #21
    KIMFAB's Avatar
    KIMFAB is offline Stainless
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    What are you going to use the acid for? More than likely you will have use for it again. I have a small wood shelter that I store all my non combustible nasties in. It just needs to be out of the weather and not freeze - altho freezing should not be a problem here. Otherwise you can buy a Spa and use it there or give it to a pool/spa place.

  2. #22
    Nitromahn is offline Aluminum
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    You can buy large boxes of Arm & Hammer baking soda so neutralizing a solution of HCl won't be a problem. Just pour some into a large plastic bucket and sprinkle the baking soda into the solution in the bucket. No big deal.

  3. #23
    mark thomas is offline Titanium
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    Quote Originally Posted by awake View Post
    I'm intrigued with the possibility that it might be possible to store it "safely" (as in without rusting out the garage) after all. In addition to gwilson, has anyone else successfully stored muriatic acid long-term inside a shop without rust problems?
    I've had muriatic acid for years in a 8'x10' shop jammed with metal stuff. I admit I have always been curious about the claims that it escapes sealed containers. I suspect what this really means is poorly-sealed containers. Or are folks saying HCI leaks through the walls of the container? I would note however that I don't open it up in the shop -- I take it outside for use, and close the container before bringing it back into the shop.

  4. #24
    ZAGNUT is offline Hot Rolled
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    i always have jugs of hydrochloric acid in my workshop without any rust problems but my shop is well ventilated and anything metal is kept oiled because of the rather high humidity here. if i'm closing the shop up tight for a few days i will move the stuff outside but generally don't worry about it too much.

    homebrew PCBs: easiest, cheapest and quickest etch is to use one part 32% hydrochloric acid to two parts 3% hydrogen peroxide. NEVER try to store it or put a lid on it though. when you're done just add baking soda and dump down the drain.

    for masking your boards look up the "toner transfer" method. for this you can use artwork done up in eagle, expressPCB or just about any drawing software. and staedtler brand red markers are far better than sharpies for touch ups or for drawing traces the old fashioned way.


    dave

  5. #25
    JohnMartin is offline Aluminum
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    Quote Originally Posted by metlmunchr View Post
    Common muriatic acid is about 10% max hydrochloric acid, not 40%.

    Concentrated hydrochloric acid is usually kept at a concentration of less than 40% unless there's some compelling reason to go to a higher concentration. Even a 25% solution of hydrochloric will make common commercial muriatic look like lemon juice in comparison.
    Hardware store muriatic acid is usually a bit stronger than that. I've got a plastic gallon jug of Parks muriatic acid that I just checked - it's 20%.

    The concentrated acid used in chem labs is 30%. You can also get fuming hydrochloric acid, which is 37%. That's about all the HCl that water will dissolve at room temperature.

    I've never had a problem storing it. If you're concerned, store it next to a steel shovel that you use often enough to keep shiny. If you see rust flashing on the shovel, you may have a problem. Store it in a garage or shed or barn that has good ventilation, don't store any good tools near it, and you shouldn't have any trouble.

    Disposing of it is simple. I wouldn't want to dump gallons at a time into my septic system, but a quart or so every now and then should be fine. Pour it out on your driveway or on the ground. If you wish, you can neutralize it with lime, lye, washing soda, baking soda, marble chips or a bunch of other things, but it's not really necessary. Hose it down for a few minutes and it will be dilute enough that it couldn't hurt anything.

  6. #26
    John Madarasz's Avatar
    John Madarasz is offline Stainless
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    Default How to STOP muriatic rust??

    I know this has been covered before, but does anyone have a dependable/reliable/proven way to neutralize and halt the rust caused by the muriatic/steel reaction?? What if the acid has splashed on cast iron /gray iron/ mild steel and etched it. Can the rust be neutralized for all intents and purposes??

  7. #27
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    awake is offline Stainless
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    Quote Originally Posted by ZAGNUT View Post
    homebrew PCBs: easiest, cheapest and quickest etch is to use one part 32% hydrochloric acid to two parts 3% hydrogen peroxide. NEVER try to store it or put a lid on it though. when you're done just add baking soda and dump down the drain.
    Dave,

    I'm interested in your statement not to cap or store the cupric chloride that you create by etching in hydrochloric acid + hydrogen peroxide -- what is your experience with this? I'm not excited about pouring a solution that contains copper down the drain, especially since my drain connects to my septic tank.

    Here is a link that has led me in the direction of cupric chloride. I've also read some links that go into detail concerning the chemistry involved, but I can't put my mouse on them off the top of my head.

    http://www.instructables.com/id/Stop...-A-better-etc/

  8. #28
    ZAGNUT is offline Hot Rolled
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    Quote Originally Posted by awake View Post
    Dave,

    I'm interested in your statement not to cap or store the cupric chloride that you create by etching in hydrochloric acid + hydrogen peroxide -- what is your experience with this? I'm not excited about pouring a solution that contains copper down the drain, especially since my drain connects to my septic tank.

    Here is a link that has led me in the direction of cupric chloride. I've also read some links that go into detail concerning the chemistry involved, but I can't put my mouse on them off the top of my head.

    http://www.instructables.com/id/Stop...-A-better-etc/
    when it's fresh it gasses off, guess i've never kept any around long enough for it to be "spent". also didn't know that it's considered hazardous waste....

    and thanks for the link, i never knew that my basic etchant mix was the basis for cupric chloride, always though there was something else involved. might have to give that a try as i do a lot of etching.


    dave

  9. #29
    applescotty is offline Cast Iron
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    Quote Originally Posted by awake View Post
    applescotty, using a 5-gal bucket is a good idea that I might adopt. How far outside (how far away from buildings) have you stored it?
    I keep it just outside the garage door.

    Scott

  10. #30
    77ironhead is offline Titanium
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    Quote Originally Posted by gary350 View Post
    If it is a hot summer day the fumes will collect on your sweety body and you will get a mild acid burn.
    I dunno about that....when I was working in plating, we got our acid in 55 gallon drums (muriatic, sulphuric, nitric, and chromic) and mixed our own solutions (700 gallon tanks on the plating lines), and we did it indoors, using pumps to transfer the acid into the tanks and adding water as needed. We then worked over those same open-topped tanks for 10 and 12 hours at a time processing parts. The only time any of us ever got a rash from the acid was if we splashed the solution directly on ourselves.

  11. #31
    Steve H. Graham is offline Aluminum
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    I pour it down the sink and run water after it. Like another poster said, the stuff they sell at hardware stores is not strong. You can pour it on your hands and have no problems, as long as you rinse it off quickly.

    Not that I am recommending this.

  12. #32
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    JST
    JST is offline Diamond
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    You would be better off to use ferric chloride.......

    IT can be "neutralized" after use by reacting it with aluminum scrap. That will precipitate the copper, and carry the aluminum off. The sewer company won't be annoyed with that, since it is not a toxic metal, and they tend to add aluminum compounds as a flocculant anyhow.

    We used to do that way back when we etched our own prototype PWBs. I had a jar of precipitated copper.

  13. #33
    toadstrangler is offline Plastic
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    Quote Originally Posted by John Madarasz View Post
    I know this has been covered before, but does anyone have a dependable/reliable/proven way to neutralize and halt the rust caused by the muriatic/steel reaction?? What if the acid has splashed on cast iron /gray iron/ mild steel and etched it. Can the rust be neutralized for all intents and purposes??

    Rinse in this order

    1 water

    2 chlorine bleach

    3 water

    4 thin oil

  14. #34
    HelEx is offline Hot Rolled
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    All plastics permeate - gases slowly diffuse through them. A plastic bottle of hydrochloric acid has a very large permeation area so they are a great source of HCl fumes. A glass bottle is impervious to the acid except for the plastic cap, nevertheless, the permeation problem is greatly reduced, and a glass bottle is a partial solution to the rust problem. HCl gas is heavy, so it would be best to store the acid on the floor. It is a good idea to have lots of baking soda and marble chips available, and absorbent "kitty litter" is often supplied in labs for the inevitable spills. Glass is prone to breakage of course, and we think of plastic as safer in that respect, but I've seen plenty of plastic bottles shatter like glass. I would always store a volatile acid like hydrochloric or nitric outside in a well ventilated area unless I had proper facilities.
    Years ago I was taught the rule for conc. acid strength is 33%, 66%, 99% - hydrochloric acid, nitric acid, sulfuric acid. Not exact but close and easy to remember.

    - Mike -

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