Wet carbon steel knife forgotten on rice cooker

"john ryan" wrote in news:ir0bal$j58$ snipped-for-privacy@dont-email.me:

Rust is mostly a hydrate of Fe(II) oxides and hydroxides (if memory serves right). Oxidizing the "rust" and chelating/complexing the Fe(III) ions should remove this. I'd recommend oxalic acid for all this. Soft water (as opposed to calcium containing "hard" water) is best. Calcium oxalate forms hard, sharp, needle-like crystals, which are mechanically poisonous (part of the green leafy parts of rhubarb that should NOT be eaten).

Any commercial rust remover like CLR.

Any acid like vinegar, lemon juice, etc. Concentrated sulfuric, nitric or hydrochloric not recommended.

Oxalic acid, dilute hydrofluoric acid ("Whink"), or "Iron Out" (contains sodium hydrosulfite and bisulfite.)

-Bob

"dadiOH" wrote in news:4dd3b644$0$30876$ snipped-for-privacy@usenet-news.net:

Hydrochloric acid doesn't do the required oxidation, so, no, not recommended. Depending on the kind of plastic sulfuric or nitric acids should work fine. You likely only need a little bit and it doesn't need to be too concentrated, with a short time of exposure. Rinse well. Wear eye protection (DAMHIKT).

The scouring powder Barkeeper's Friend has oxalic acid in it. I'd make a paste, apply it, and wait. Keep the paste moist if you can. For example, lay a moistened paper towel on top.

BF is not very abrasive, but I'd be careful about rubbing it on plastic, which is quite soft.

Cindy Hamilton

FFS DON"T EVER USE HYDROFLUORIC ACID, DILUTE OR OTHERWISE, UNLESS YOU WORK IN A LAB WITH ALL THE REQUISITE SAFETY GEAR!!!!!

Graham

It's available in the laundry aisle at the supermarket in a little brown plastic squeeze bottle for removing rust stains. It's called "Whink". It's important to wear rubber gloves when using it cuz it will F! you up (in a bad way) if absorbed through the skin.

-Bob

Christ!! It's one of the more dangerous acids and should NOT be available to the general public. I'm fully aware of the dangers having used it under lab conditions and having to develop procedures in the case of accidents. These days, my processing work is handled by a contract lab so I don't go near the stuff. Graham

"graham" wrote in news:xxTAp.32369$ snipped-for-privacy@newsfe14.iad:

It's all in the dose. Moreover, HF is readily soluble in water, so it washes away easily. I am NOT recommending sniffing it or drinking it, or washing your hands in it. On the other hand, it is present in toothpastes in various forms as a minor, but active ingredient.

BF powder is 100% oxalic acid

It scares me too. Rumoured to go straight for the bones.

But the stuff in toothpaste is NOT HF, it's NaF. About as dangerous as common table salt.

OK, so 5g may well kill you, it takes a bit more table salt. Whereas HF will kill you at 30ppm in the air...

Andy

does the rust stain affect the operation of the rice cooker?

The MSDS indicates 5-10% by weight.

I generally use it to remove baked-on grease from cookware.

Cindy Hamiton

Andy Champ wrote in news: snipped-for-privacy@eclipse.net.uk:

NaF or SnF2 would become HF when it gets acid (like in a stomach). And [H+] is always there in some concentration.

MSDS for this (Whink rust remover) doesn't mention HF at all, nor any fluorides. Mike

Did you actually look?

-Bob

It should be taken off the market for ordinary consumers. That concentration of HF (1.5-3.5%) is dangerous. If any is absorbed by the skin, it causes gangrene! Graham

Whink makes several products with "Rust" as part of the name. Not all of them contain HF acid. The MSDS for their product named "Rust Stain Remover" and sold in a brown bottle, does clearly list "Hydrofluoric Acid (Hydrogen Fluoride)" as an ingredient and has all kinds of warning statements, including this line in the Emergency Overview section: "Will penetrate skin and attack underlying tissues and bone."