How to clean the rust marks ?

[diytoolbox]

Some rust marks seem to be solidly stuck on the metal of the blade, and they just wouldn't come off.
Could it be pitting? or rust marks? They look like sticky hardened glue or dried black oil patch as well on the surface.
Not sure what they are, but was guessing they are one of those above.
How could they be cleaned 100%? Tried ISO alcohol, WD40 and Wire brush bit on the hand drill. Nothing seemed to be able to clean them off.

 

[--Tom--]

Powdered barkeepers friend contains some oxalic acid which helps.

Otherwise wire wool and wd40 if that’s what you have

 

[diytoolbox]

This rotary grinder tool from ALDI bought a few year ago for £20 is still working in the shed. The stone grinding bits attached to the rotary tool worked great for dersuting and polishing the old rusty tools. It wasn't good for pitting on the blades.

https://www.aldi.co.uk/ferrex-mini-bench-grinder/p/827478749277000

 

[BC'er]

Vinegar, or acetic acid to be more precise, will convert rust making it easy to remove. All oil and grease etc. must be removed first; oven cleaner aka caustic soda is good for that. Soak for a day or so in the vinegar and brush off under hot running water. The acid will etch and make dull polished surfaces at least in carbon steel. Very good for sharpening files too, but again, don't leave them too long.

 

[ChaiLatte]

If you do use the acetic acid treatment, you can localise it by building a dam of hot glue or silicone sealant around the area to be treated. Then you do not necessarily need to immerse the entire item.

A picture of the item might help.

 

[diytoolbox]

I used to immerse the whole tools into vinegar for derusting around 10 - 12 hours, then wash them under the running tap water, and dry them with hair dryer and towels. This was not good way. The tools developed heavy flash rust in next few hours which were really bad. They had to be cleaned again by WD40, and looked worse than before. The wooden handles would smell of acid for long time.

Now I am not using vinegar at all for derusting. I would just apply WD40 on the rust part of the metal leave them for around 30 minutes, and then use the rotary tool to clean them up. The tools get shiny again with the rotary tool polishing. Of course it cannot treat heavy pitting.

 

[ChaiLatte]

This was not a good way. The tools developed heavy flash rust...

Because you have a fresh, acid-etched iron surface that you expose to oxygen, which the heat exacerbates.

The vinegar itself is not really the problem; it is the post-vinegar _process_ that could benefit from fine tuning.

Rinse and scrub submerged in tap water, move to a tub of deionised water and leave submerged there. Then, once you withdraw them from there, use a proper water-displacing corrosion protection treatment (i.e. almost anything that does not have 'W' or 'D' in its name). The exposed (chemically-active) surface of steel never really sees any oxygen that way.

Not relevant to a plane, but I did find this one, which is food-safe, if somone had that need:

https://www.ebay.co.uk/itm/27649850196

 

[diytoolbox]

Because you have a fresh, acid-etched iron surface that you expose to oxygen, which the heat exacerbates.

The vinegar itself is not really the problem; it is the post-vinegar _process_ that could benefit from fine tuning.

Rinse and scrub submerged in tap water, move to a tub of deionised water and leave submerged there. Then, once you withdraw them from there, use a proper water-displacing corrosion protection treatment (i.e. almost anything that does not have 'W' or 'D' in its name). The exposed (chemically-active) surface of steel never really sees any oxygen that way.

Not relevant to a plane, but I did find this one, which is food-safe, if somone had that need:

https://www.ebay.co.uk/itm/27649850196

A good point actually. A topic which could do with the fine tuning.