Blueing

[petro1headParticipant @petro1head]

[petro1headParticipant @petro1head]

Years ago, when i spent most of my school days in the enginnering workshop we used to blue a lot of the work we made. If i remember we heated the part up and dropped it in an oil solution, loved the smell

So whats the modern equivant as i fancy blueing some of my work now?

[bernard towersParticipant @bernardtowers37738]

Clockmakers still blue their screws the same way as always by heating the screws whilst laying in a bed of brass swarf ( heated underneath) until they turn blue then quench in oil. Alternatively you can black your parts chemically, just google blackit solution.

[Martin KyteParticipant @martinkyte99762]

Any thin clean oil will do. The colours develop just by heating to tempering heat and stopping at blue. The oil prevents the process from continuing by cooling the part and providing an oil film to protect the surface. The colour comes from the thin oxide layer developed on the surface when heated and is an optical phenomenon caused by interference which is why the colours change according to the thickness of the oxide layer.

Oil does however make the surface look blacker presumably by mopping up the blue photons somewhat.
regards Martin

Edited By Martin Kyte on 28/03/2023 12:33:34

[petro1headParticipant @petro1head]

Cheers guys.

Did a bit of Google work and see that gunsmiths blue their barrels using **THIS**

I also found a good video on how to use

[DalboyParticipant @dalboy]

This can be a confusing term as petro1heads post above compared to bernard towers post which are both called blueing.

See Clicksprings video.

[jaCK HobsonParticipant @jackhobson50760]

If you can get hold of low temp heat treating salts then the process is much easier to get repeatable. I had to buy 20kg bag, with a minimum £50 pallet delivery… I haven't used em much but I hoard them.

[SillyOldDufferModerator @sillyoldduffer]

The thing about bluing is how thick the protective layer needs to be.

An attractive thin layer suitable for decorative purposes is achieved as described above, but it's not hard wearing.

Deep hard-wearing bluing requires heat and repeat treatment with nasty chemicals, such as molten Nitrates. Coild be done, but not really a home workshop process.

'Cold Blue' is a safer alternative, often based on Selenium. Much used to touch up worn firearms. The resulting layer isn't particularly tough, but it's easily redone.

A thicker protective layer can be achieved by plunging red-hot metal into dirty engine oil. Results vary, black rather than blue, and unlikely to be pretty.

Dave

[Martin WParticipant @martinw]

I have used a cold bluing paste which seems to be quite resistant to abrasion and that is Birchwood Casey Perma Blue which can readily obtained from the this site. The depth of colour can be controlled by the length of time that the paste is left on the metal, this can be a bit variable so requires a bit of experimentation to get a even depth of colour

Martin

[petro1headParticipant @petro1head]

So its a toss up between these three

 

Edited By petro1head on 28/03/2023 15:44:35

[Anonymous]

Posted by petro1head on 28/03/2023 13:14:50:

Cheers guys.

Did a bit of Google work and see that gunsmiths blue their barrels using **THIS**

Gun barrels aren't cold blued they are hot blued/blacked, if a gunsmith used cold blueing it would just be a minor mark or scratch they were trying to hide. Not used or found a decent hard wearing cold blue and I've tried over the years.

[OldironParticipant @oldiron]

I used the Nickerson Cold Blue on all the toolholders I made. Got pretty good results with it. Parts need to be very very clean. I warmed them up a bit till they were just hot enough to handle then duncked them in the solution till they looked about right. Then oil and wipe over. Look very good.

I got good results on another job after reusing the solution.

regards

[Fowlers FuryParticipant @fowlersfury]

I'm really not being facetious but I wish some folks posting queries would first try the site's "Search for" box. There's already a wealth of information and advice on the subject – "Blueing".

Whichever method is adopted, worthwhile protection is possible by the (regular?) application of black shoe polish to the metal surface followed by light buffing.

[petro1headParticipant @petro1head]

opps

Edited By petro1head on 28/03/2023 21:19:06

[petro1headParticipant @petro1head]

Posted by Fowlers Fury on 28/03/2023 17:57:33:

I'm really not being facetious but I wish some folks posting queries would first try the site's "Search for" box. There's already a wealth of information and advice on the subject – "Blueing".

Wheb someone starts a reply to a post "I am really not being facetious" it usually means they are

I did a search and there were only 7 replies.

[Fowlers FuryParticipant @fowlersfury]

There are a total of 87 replies according to the search box. Yes, there may be repeat postings included in that total. My point was that there's useful information already on the site.

[petro1headParticipant @petro1head]

Well thats very strange as i hva just searched "blueing" again and only get 7 topics

Edited By petro1head on 28/03/2023 21:36:16

[Fowlers FuryParticipant @fowlersfury]

[petro1headParticipant @petro1head]

So we are both right, 7 topics and x number of posts.

well i think we have covered that

[Grindstone CowboyParticipant @grindstonecowboy]

Well, you missed this one,

Rob

Links to https://www.model-engineer.co.uk/forums/postings.asp?th=177264

[petro1headParticipant @petro1head]

Posted by Grindstone Cowboy on 28/03/2023 22:20:31:

Well, you missed this one,

Rob

Links to https://www.model-engineer.co.uk/forums/postings.asp?th=177264

Cheers, ordered some of the Nickerson from Amazon

Edited By petro1head on 28/03/2023 22:35:54

[bernard towersParticipant @bernardtowers37738]

Surely the gunsmiths do browning

[Sonic EscapeParticipant @sonicescape38234]

This method seems to produce very good results. The parts are put in hydrogen peroxide to make them rust quickly. And then they are boiled in water.

[SillyOldDufferModerator @sillyoldduffer]

Posted by bernard towers on 28/03/2023 23:15:03:

Surely the gunsmiths do browning

As in 'Brown Bess'*, yes. Before bluing, many firearms were 'browned'. Have to look up the exact process, but it consisted of repeatedly building up layers of fine rust and polishing them back to leave a protective brown covering.

In the usual way, the gun-trade became remarkably conservative, and insisted on calling any protective layer 'browning' for many decades after bluing had become dominant. In the same way, 'ball' ammunition has been cylinder-conoidal since about 1870.

Dave

* The origins of the name 'Brown Bess' are uncertain. The musket was obviously 'brown', but the nickname may have come from another friend of soldiers; at the time 'Brown Bess' was slang for a prostitute. Or vice-versa, the ladies were named after the gun.

To add to the confusion, browning as in bluing has nothing to do with the prolific gun inventor John Browning.

[Mick B1Participant @mickb1]

I used G96 cold blue 'creme' (fancy word, I'd call it a paste) on the naval cannon in my pic album, in 2005. It still looks the same now AFAICS, with one light touchup at some date in between.

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