Brake fluid?

[celtan]

And yet, we spend all sorts of money on lubricants such as Pecard and Leather care products, based on animal grease.

Or do you mean the seepage out of the cleaned scabbard? That is utterly true, it does become a rusty dye.

Originally Posted by Matchlock

I definitely share your opinion, 'Nando,

And it should not be forgotten that any kind of lubricate will irreversibly soil leather and textiles.

Best,
Michael