Which oil for blueing steel screws?

Which oil is recommended for blueing steel screws for clocks? In many clock build books and descriptions after polishing the screw and heating to blue dropping the screw into "oil" is the only description given.

I have seen cooking oil, hydraulic oil, engine oil etc mentioned in various places but no definitive answer. Does anyone have a preference or indeed the "best" option please?

Edited By Bizibilder on 23/07/2017 20:20:38

I was under the impression that using oil 'blackened' steel. For bluing I would of thought that you watch the colouring then quench in water. have a look at @ 'Clickspring' website he blued up some steel screws for his skeleton clock by heating them in a tray of brass chippings & then leaving to cool when he was satisfied at the depth of blue he needed. No doubt others will have their own version to pass on.

​George.

I've just had a look at Clickspring video on YouTube... I stand corrected... he uses oil but doesn't say what type... it looks like very light oil, possibly hydraulic maybe even vegetable oil?

https://youtu.be/KXzyCM23WPI

George.

Try...



​Geo.

Edited By mechman48 on 23/07/2017 20:47:55

Thanks George - I've seen that one - another "oil" recommendation!

You can use water, it is only for stopping the colour from running further, the only advantage of oil is that the steel will not rust if you forget to remove the water. Niko.

Edited By mechman48 on 26/07/2017 14:35:23

I've used cheap supermarket own-brand margarine with some success. Definitely not motor oil, although Castrol R would make the workshop smell wonderful!

I've used rape seed cooking oil after heating in a tray of brass filings. It came out OK for me; just a case of experimenting.

Alan