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How do i colour steel (blueing and blacking) ?

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Chris machin08/04/2012 10:27:37
59 forum posts

Hi , Hope everyones well ?

Having completed my first project succesfully (elmers Tiny in Brass) I'm looking at making elmers #24 beam engine. As i'm wanting my engines to look attractive and the beam engine has some parts in steel , i'm looking at blueing or blacking some of the compnents.

Can someone tell me how to blue or black steel , i assume its a chemical process ? The parts will be small common mild steel parts that are either milled or turned.

Any help appreciated


Saxalby08/04/2012 11:25:14
163 forum posts
15 photos

Hi Chris

I used the cold blacking kit from So far very impressed with the results.

Regards Barry

Michael Gilligan08/04/2012 11:41:55
15688 forum posts
683 photos


I don't know if it's appropriate to the size and shape of your components, but; the traditional clockmaker's technique for Blueing only requires heat.

It is often convenient to support the components in a block of brass, or on a tray of brass filings.

Joy of joys! ... a Hot-Air Gun, as used for paint-stripping, is often adequate as a heat source.


Edited By Michael Gilligan on 08/04/2012 11:50:43

chris stephens08/04/2012 12:06:59
1045 forum posts
1 photos

Hi Guys,

There is a video on polishing and bluing screws that warrants a viewing for all those interested n clocks and watches., as well as those interested in polishing and bluing.smiley

As I have said before his other videos are well worth watching.


Clive Hartland08/04/2012 16:00:51
2561 forum posts
40 photos

Notice the dinky lantern chuck used to polish the screw ends, I did not see any quenching of the screws when blueing?

The quality of blueing and lustre is dependant on the surface finish of the metal, a nice example of the term, 'Finesse'


Packmule08/04/2012 17:34:38
97 forum posts
5 photos

I seem to recall in the dark old days when at school we would heat up a work piece to a nice red and then emerse it in old engine oil .

Jon08/04/2012 21:18:31
997 forum posts
49 photos

Looks like a lot of faffing about in that video link, job done 2 mins tops inc polish.

Agree theres some anomallies, second cut file to diamond paste i think not along with no quick cooling.

Anyone thats ever done by this similar means will know the heat carries on rising in the part after heat is removed no matter how slow the build up is.

Used to do long items many years ago, thats hard screws are easy. If overdo it just repolish and heat again, good enough for £6 figure value items on show.

Supposedly you can cool by using parafin, have tried but didnt seem any better.

To get a translucent colour in stainlesses is really trial and error, at best a brown/purple.

Theres also chemical blacking hot or cold and the old heated oil as mentioned in above post.

Jim Greethead09/04/2012 08:50:00
131 forum posts
8 photos

I use Blackfast. Don't know where you buy it elsewhere but there is a place in Queensland (Australia).

It is easy to use, comes with all the containers already labelled and lasts for a long time. The bloke who recommended it to me had had his so long the the suppliers had moved twice in the meantime.

And it is water based and cold. And idiot-proof - I get results every time.


CHRIS WOODS 109/04/2012 11:24:17
38 forum posts
3 photos

Try Birchwood Casey Gun Blue from any shop that sells air rifles, shotguns and the like in the UK. (Yellow Pages) This was used to blacken loco. buffer heads. Also I've bought tubes of cream called 'KOLDBLAK' by Jenolite from a stand in a model engineering show, 'though the stuff did not have much of a shelf life.

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