Super. Will give that a try.I was wondering if heating and then applying waste oil would work but then I read online 'heat the polished areas to a cherry red, then let it ‘air-cool’…the impurities in the carbon steel will naturally re-occur on the surface, producing a near-match for the mill-scale', which is kind of what you said! Never knowingly tried it though?
Many thanks for your help. I've added that site to my favourites!Black antiquing fluid's probably the best product to use for the colour although it won't give you back the mill surface texture:
http://www.jpennyltd.co.uk/shopping/pgm-more_information.php?id=50
Excellent help. Many thanks.Heating to red and allowing to air cool will get the black back.
You might want to feather the heat away from the bit you have ground to blend it in a bit.
The grind marks etc will still show, if you want more scale to try and cover them up a bit then try an oxidizing flame on it.
Another way is wet a sponge with salt water and dab on the ground surface once a day for a couple of days. Once it's rusty heat it up to dull red, turn the heat off. As soon as it cools to grey go over it with a wire brush .
Many thanks for the helpful information. I do Blacksmithing at a Forge from time to time and have blackened metal work in the fire. Just wondered if a butane blow torch would get up to the right temperature to make the metal glow. I'll have a play around with some polished scrap pieces this weekend.This is a 60g flap disc,
View attachment 164638
Heat to a dull red
View attachment 164639
Then air cooled until grey then quenched in water
View attachment 164641
If you leave to air cool fully the scale will be stuck in there better. Or you can wire brush it once it's cooled from red.
You can heat it more than once if , like that one, there is a ground area with no scale build up.
I heated that in an enclosed furnace with a pretty nutral flame, you would get a better result with a blow torch