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Old 27th Mar 2019, 1:20 pm   #16
ColinTheAmpMan1
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Join Date: Jan 2012
Location: Wimbledon, London, UK.
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Default Re: Rust removal from steel component on the cheap.

I am a retired chemist but I don't actually know what is going on with the OP's mixture. That said (I was an organic chemist, which goes some way to explaining my ignorance), vinegar is acetic acid - it just comes in different colours depending on the origin (malt vinegar is brown, white wine vinegar is almost clear).

Sodium bicarbonate is baking soda, not washing soda. Washing soda is sodium carbonate. They are not the same thing. The bicarbonate is more acidic than the carbonate. I could explain if anyone needs further information (probably not).

Oxalic acid is poisonous and present in rhubarb - stem and leaves. There is just less of it in the stem. It gives rhubarb its sharp flavour. It also removes rust stains from stuff. Really good on rust-stained baths!

Citric acid is a white powder and is present in citrus fruits like oranges and lemons (there's a clue in the name). It is frequently found in descalers, where phosphoric acid used to be employed. It is less hazardous than phosphoric acid, probably why it was replaced.

Phosphoric acid is probably still a constituent of cola drinks.

Some descalers for domestic equipment contain glycolic acid.

The Philpott wrote:

"I do recall that a mixture of salt and vinegar often stinks to high heaven once it's been used to clean certain metals. It was enough to put me off !"

I am flummoxed. The smell of strong vinegar can sometimes be a bit much, but I can't quite see how putting metal into a mixture of things which you put on your fish-and-chips can give a bad smell. Maybe there was something else associated with the metal in question.

I have never used Jenolite, but I have used Evaporust, which I found to be good.

The stuff used for etching PCBs is ferric chloride, not ferric oxide. Some people think that rust is ferric oxide, but it is more likely to be ferroso-ferric oxide and carbonate.

Temperature is nearly always significant in chemical reactions. At higher temperatures, molecular motion is faster, which means that the molecules come into contact with one another more frequently (this is thermodynamics).

As an aside, I have a bee in my bonnet about the commonly-used phrase "nasty chemicals". Things like liquid hydrogen fluoride, bromine and some other stuff is truly dangerous, but most of the chemicals that we come across on a daily basis warrant care and caution, but are far from being "nasty chemicals". After all, everything (perhaps apart from a perfect vacuum) is a chemical or a mixture of chemicals. It may be of interest to know that our stomach acid is hydrochloric acid, which is why vomit tastes acidic. It is quite a strong solution of hydrochloric acid, too, so were are effectively quite dangerous on the inside!

OK, rant over.

Colin.

Last edited by ColinTheAmpMan1; 27th Mar 2019 at 1:26 pm. Reason: Info on temperature.
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