www.ultimatehandyman.co.uk

A few decades ago on a machine shop engineering course, one piece I made was a centre punch, this was heated bright red and drop in oil
as part of the harding / temper treatment, this left the punch with a black finish, the oil at the time I believe was sperm whale oil which is long gone off the market.
Now what I want to achieve is the black finish that the oil gives on some hand made strap hinges so what oil do I use now ?.

Pretty much any oil will do it. There are also ways to chemically black, without the need to heat the item. Probably more expensive for a one off use though.

Well after trying all the car & bike engine and gear oil's, syn' and mineral, linseed turn out the best.
just need to buy a gallon now.

izalarfin wrote:Well after trying all the car & bike engine and gear oil's, syn' and mineral, linseed turn out the best.
just need to buy a gallon now.

Get to know your local cricket club..........that's the oil they use on their bats..