Muriatic acid mistake!

mariner3302

mariner3302

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First off, if you are thinking of using muriatic acid on cast iron, STOP. Yep, STOP and don't do it. I read online and saw a video that demonstrated it as effective and a safe method of cleaning and derusting. And to that end it does work. EXCEPT (and after it was on already), I found gobs of sites and threads saying don't use it on cast iron. One said that he left it in a soak tank for a day or so and it actually softened the cast iron so much he could remove some with a fingernail. I used it to take some flash rust off the legs on my 1937 South Bend 11" lathe. Only after applying it with a spray bottle did I read that it gets in the grain and continues eating cast iron for years if not completely neutralized and/or removed. So I scrubbed the legs with Soda Ash because it was handy and a green scratchpad. The legs are all white now from the soda ash (about 50/50) rinse and scrub. The worst is I am now worried about painting the legs.
So the question is, will soda blasting neutralize muriatic acid on cast iron or would media blasting with black diamond be enough? The legs are almost all back to metal except a couple spots where the black original fillers were applied.
 
Yeah, read about a guy who had some in his shop and rusted everything exposed to air! I threw that stuff out and it makes me think it could have been responsible for some things rusting lightly in the shop.
 
It used to be sold in very thin poly bottles and strong (36.5%) and I had some in my garage. One of the bottles had a tiny crack in the plastic and over time I started seeing rust on my tools- Fortunately I caught it in time- I store it outside now- one of my mikes seized totally and got ruined
M
Ironically it's very good at removing rust when in liquid form
 
One thing to also remember that I found out the wrong way is. Is Cleaning outside calipers or layout pointers with a spring steel hoop on top. DONT CLEAN SPRING STEEL WITH VINEGAR! I recently got some dividers from a garage sale really nice made in Germany. Had minor rust figured a little soak in vinegar which I’ve done a lot with great results. Just never spring steel. Well ten mins. Soaking I went to brush and found the divider in pieces. Hoop was broke in pieces and arms were just laying there. S.O.B! At least it was only two dollars but a lesson well learned! I would never use muratic acid for steel just for the fact that it rust just as bad afterward as before cleaning and it stinks. Only use that for etching concrete.
 
To the original question on neutralizing acid soaked cast iron I would imagine a generous spray of some caustic oven cleaner on the part will neutralize the acid in the pores of the CI. Sodium hydroxide (lye) has long been used to clean steel and cast iron (BUT NOT ALUMINUM) car parts. Do a test on a small area first as there may be a strong reaction at first. Once all the acid is neutralized I would wash with water and dry quickly. Use a good rust preventing primer before painting.
 
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Had a 1 gal plastic jug of sulfuric acid under the bench. Over time it ate thru the jug and now I have a 1 foot crater under the bench clean thru the 4" concrete. Nasty stuff these acids.
 
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