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| Dissolving broken taps |
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| AdeV:
--- Quote from: craynerd on July 28, 2010, 07:07:50 PM ---If you don`t mind me asking, where did you get it from as Conc. Nitric Acid - I thought best you could get without some registration would be about 40%. Only place I could think of was artist supplies as they use it for etching copper but then again, this wasn`t conc.? No reason...just curious to know! Nitric acid will be great for this, really quick and won`t touch the ally, or at least shouldn`t do! Let us know. --- End quote --- Well, you _can_ buy it straight off eBay, 1ltr @ 70% for less than £25 delivered... but mine came from a friendly chemist at Dad's works. The strength of the acid hasn't been written on the bottle, unfortunately, but I'm told it's "probably" 70%. I plan to test on a sample, I'll drill a hole, jam the broken off end of the tap in there with a smidgeon of WD40 (to match the real deal), then I'll add acid & see what happens. Getting the acid back out of the hole will be the interesting part... I will have to try not to overdo it, so that it all gets converted to whatever it turns into when it's eaten steel... |
| AdeV:
--- Quote from: Tinkering_Guy on July 28, 2010, 07:54:19 PM ---Wikipedia sez: --- Quote ---Nitric acid is miscible with water and distillation gives a maximum-boiling azeotrope with a concentration of 68% HNO3 and a boiling temperature of 120.5 °C at 1 atm, which is the ordinary concentrated nitric acid of commerce. --- End quote --- I think 40% HNO3 is plenty strong. I certainly wouldn't want to mess about with anything stronger without a complete lab setup (fume hood, granite bench, 3mil nitrile gloves, et cetera). --- End quote --- Other than the gloves (which aren't 3mm), I don't have any of that stuff... what I do have is a very big building, so if anything does start fuming wildly, I have plenty of "get the hell out of there" space. Although I could do with it -not- raining nitric acid inside the building.... |
| raynerd:
AdeV, ahh good job. To be honest, concentration won`t matter too much...just the stronger the quicker it`ll work. I`d watch it doesn`t get too hot. I`ve stripped the copper off an old 2p coin a few times with Nitric Acid and it does get very hot. You might want to do it in a container and try and put the container in a cold water bath to cool the acid down. I have an idea that you may want to keep prodding the tap with something. Sounds silly but I think it`ll probably crumble in a shorter time rather than completely dissolve away. Regarding cleaning up. I think the HNO3 will be reacting with the iron and so it`ll form iron(III) nitrate, Fe(NO3)2 and H2 gas but you`ll still have HNO3 there because it`ll have been in excess. I`d give it a good clean in water to dilute it and then put it in a good bath of Bicarbonate of Soda to neutralise any acid left on there. Good luck...take a video!! :worthless: |
| Lew_Merrick_PE:
--- Quote from: AdeV on July 29, 2010, 04:35:36 AM --- --- Quote from: Tinkering_Guy on July 28, 2010, 07:54:19 PM ---Wikipedia sez: --- Quote ---Nitric acid is miscible with water and distillation gives a maximum-boiling azeotrope with a concentration of 68% HNO3 and a boiling temperature of 120.5 °C at 1 atm, which is the ordinary concentrated nitric acid of commerce. --- End quote --- I think 40% HNO3 is plenty strong. I certainly wouldn't want to mess about with anything stronger without a complete lab setup (fume hood, granite bench, 3mil nitrile gloves, et cetera). --- End quote --- Other than the gloves (which aren't 3mm), I don't have any of that stuff... what I do have is a very big building, so if anything does start fuming wildly, I have plenty of "get the hell out of there" space. Although I could do with it -not- raining nitric acid inside the building.... --- End quote --- Guys, do not attempt this inside a building without a fume hood! Set it up outside (with a fan set to blow away the fumes)! Wear a face mask and feed a "light trickle" of air into the mask. You do not want to get a lung full of any concentrated acid fumes! I work with concentrated acids fairly regularly. I have a pressure regulator that I set to 3 psi that I feed air into my face mask with (using a piece of 1/4 inch ID tubing with small holes punched in it to distribute the air). I have a board (1 X 4) screwed to the side of my house to which I can attach a piece of polyethylene sheeting (camping tarp) to give me a dry area to work (I live in western Washington State where drizzle is to be expected). I have cinder blocks set into the ground on which I can stand a fan to assure that the fumes are blown away from my house. I have several polyethylene storage containers to hold whatever I am working on and the acid. A brick on the "lid" keeps animals and kids away from the dangerous stuff (and all the kids in the neighborhood know not to mess with things in this area). I place a piece of polyethylene sheeting on the ground under the container with raised edges to make a "catch basin", cover that with newspapers covered in baking soda to catch spills -- and have an empty plastic bucket at hand to dump excess (or used) acid and a hose "at the ready." I have another plastic bucket "at hand" with a baking soda/water mixture ready for the pieces I pull out of the acid processing. This all adds about an hour (set-up and clean up) to any "acid job," but it is cheap at twice the price! About half of what I do with acids is desmutting hot rolled steel (using hydrochloric acid). About one-third of what I do is passivating stainless steel (using sulfuric acid). The balance are processes dealing with other acids. Getting a lung full of acid fumes is not a "good thing." Desmutting hot rolled steel: If time is not an issue, salt and vinegar will do this job for you -- just be prepared to wait a couple of days for good results. If time is an issue, muriatic (moderately weak hydrochloric) acid speeds things up. Use care as the fumes are nasty! After you have removed the material from either bath, neutralize the acid (baking soda works quite well) and rinse thoroughly. I find that a coating of phosphoric acid (Naval Jelly), rinsed well, and dried -- followed by a light waxing with a carnauba-based wax (Treewax is the most common brand in the U.S.) lets such material sit on my "stock shelf" for years without rusting. As with anything, RTFI -- Read The Fine Instructions! |
| Tinkering_Guy:
Thanks for the details, Lew. I could see feeding the air into the mask from the top to blow any fumes downward away from your nose -- and cool your forehead while it's at it.. :thumbup: What sort of mask are you using? :offtopic: Speaking of masks, I saw this in a recent flyer and burst out laughing so hard I startled my SBH -- and the cat. :lol: |
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