How to proceed, or how to remove dried Cosmoline.

[Bod]

Latest car boot find, Disston No7 1917-1928.
Very little used, dark colour on blade, very light rust, never been sharpened(?) handle with thats polished through use.

Removed handle, started to scrap rust with razor blade, rust powdered up as expected.
Then the dark colour started to come off in shavings!

Now I think this an old rust prevention treatment that has dried out.
Scraping leaves the metal still covered with a thin layer, meths has barely any dissolving power against this layer.

Using wire wool and meths, has slighty more effect than cotton wool.
Are there any better solvents, (readily available!) that I could try.
I don't want to use any abrasive, the etch is unrusted, under this layer, so should be in good condition.

Bod

 

[deema]

Try pure Terpentine which is an excellent solvent and removes most stuff, if you don't have any to hand diesel is also brilliant. For the ultimate I've ever found, if you know someone with a spray gun, Gun Wash.

 

[NazNomad]

Try a heat gun.


From Wiki ... ''One method that may help remove cosmoline is to apply gentle heat sufficient to melt the waxy hydrocarbons, the cosomoline may then be wiped off metal or allowed to drip off of wood.''

 

[ED65]

Yeah if it's anything like Cosmoline then heat or solvents are the usual two methods. If it was still a gel I would recommend you try a steam cleaner but since it's hardened a heat gun is probably a better option.

On the solvent side of things, if you don't have any turpentine you can try WD-40, but white spirit would probably do it too.

Be ready with lots of kitchen paper for wipe up!

 

[memzey]

Are you 100% sure it's cosmoline? Could well be plain old linseed oil which also does a good job of preventing rust and would have been used for that on tools in the timeline you give. Cosmoline comes off quite easily with WD40 in my experience but I've never encountered anything that old so could be wrong.

 

[ED65]

Aged linseed oil does seem far more likely. If that's what it is then WD-40 or white spirit are unlikely to work, turpentine might because its solvent action is stronger but I think acetone would probably be the solvent to try.

Handle is off yes? If so another option is to spray it with oven cleaner and leave it to work for a couple of hours covered in plastic (bin liner or cling film) so it doesn't dry out. Won't harm the steel, will degrade any form of grease or oil no matter how old.

 

[bugbear]

I would try a range of solvents; I once thought that solvents formed a simple hierachy, with "powerful" ones at the top (e.g. MEK, Acetone) and "weak" ones at the bottom (white spirits, diesel).

But this is quite wrong.

Solvents and Solutes need to match, simple as.

e.g. many adhesive label glues e.g. price tags and "special offer" stickers dissolve nicely
in white spirit, but are untouched by methylated spirits.

BugBear

 

[Biliphuster]

As I understand it, solvents won't do much to a cured linseed oil finish as the fatty acids have crosslinked and formed a ploymer. The whole coating is essentially one giant molecule. Having said that, would linseed oil go that dark?

 

[D_W]

As I understand it, solvents won't do much to a cured linseed oil finish as the fatty acids have crosslinked and formed a ploymer. The whole coating is essentially one giant molecule. Having said that, would linseed oil go that dark?

Old linseed oil on planes will go very dark.

I'd be hesitant to put a heat gun on a saw. The temper temperature on a saw is pretty high, but that doesn't mean you couldn't cause warpage below it.

Solvents or boiling water would be my choice (solvents would be my first choice).

 

[ED65]

As I understand it, solvents won't do much to a cured linseed oil finish as the fatty acids have crosslinked and formed a ploymer. The whole coating is essentially one giant molecule. Having said that, would linseed oil go that dark?

Cured linseed is indeed a type of polymer and most weak (non-polar) solvents, such as white spirit, will have little to no effect on it. This is where polar solvents come into their own, starting with acetone which is the weakest of the solvents available that'll usually do the trick.

And yes, linseed oil can go very dark after a long time, especially with microscopic dirt embedded. After a century or more a thin film of dirty, aged linseed oil will appear to be a sienna colour, somewhat like what we think of as tobacco staining, in a thicker film it would be about the colour of decent chocolate.

 

[Bod]

I've contacted the Disstonion Instute, if this is the original factory anti-rust coating, then it's Cosmoline, and worth trying paint thinners.
Having scraped this dark layer, I'm inclined to think it's a dried grease rather than an oil based substance.

Bod