# Cold blue (blu) liquid.



## Munty Scruntfundle (20 Jan 2020)

Hi there, how ever you spell it, does anyone know of a uk supplier that will dispatch a bottle larger than 250ml?

I can only assume people in the UK aren't expected to blu anything larger than an M8 nut, unlike the people in the states who dunk their houses in the stuff and can order by the barrel!

Many thanks.


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## AES (20 Jan 2020)

Not quite sure if we're talking about exactly the same thing Monty, but I bought a 100 ml bottle of "Marking Out Blue" from Arc Eurotrade (usual disclaimers). 

Just to be clear, it's a very liquidy stuff (about the same consistency as tap water) that you spread on metal (with a tiny kids' painting set brush) to make your marking out lines stand out clearly. That amount should last you a lifetime (though I've never tried painting my house with it)! It has the advantage that it will happily mark just about any metal, but you do normally need to make sure that the surface to be blued is completely grease-free first.

BTW a cheaper alternative to the above is copper sulphate crystals (from your local dispensing chemist). Like the blue above you need to de-grease the job first. Unlike the blue above it only works on steel. Apart from being cheap though, another big advantage of this is that you just mix the crystals with water and can mix up any quantity you want. Again a small bagful will last years, and a pre-mix, kept in, say, a jam jar with a decent lid, will also last ages. 

Then there's "engineer's blue". This is much more like a grease in consistency and is used, amongst other things, for showing up high spots on (supposedly) flat parts (you just spread a little on the surface to be checked, rub the job over a surface plate/sheet of glass/w.h.y. and it shows low/high spots). I bought a 38 gr time again from Arc, and again, such a tin should last you a lifetime.

Sorry if any/all of the above is teaching granny all about egg sucking Monty. But I genuinely do not know exactly what you mean by "cold blue (blu) liquid" (unless you meant something to add to your diesel to top sit freezing)!  

P.S. There's lots of other suppliers for both engineers blue and marking out blue, I just happened to use Arc.

HTH


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## Phil Pascoe (20 Jan 2020)

I suspect he's talking of something like gun blueing.


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## AES (20 Jan 2020)

Oh, if so, then dunno, sorry - though I suspect that a visit to some of the model engineering suppliers listed in the sticky at the top of the General Metalworking section could help.

Edit for P.S. And IF (a big if) I remember rightly, there was an article about gun blueing in a copy of "Model Engineers? Workshop" mag a couple of years back. Worth a check of their web site (again in the above sticky)?


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## Richard_C (20 Jan 2020)

That brought back memories of working in a proper engineering company in the early 70's - admittedly in HR not as an engineer - so I had a look around on the internet. I'm sure in Hawker Siddeley Dynamics we used it by the bucket-full, but we did have over 1500 machine tools churning out aerospace precision parts. Whole place, even the offices, had a faint smell of cutting fluid some days. 

This company claim to do 930ml and bigger on request:

https://www.waltersandwalters.co.uk/Dyk ... 0600-80400

Looking round some more there is a suggestion you could make it yourself, prussian blue + meths for the drying sort, + oil for the non drying sort. With or without shellac flakes. I wonder if a small tube of prussian blue oil paint from an arty shop and some meths would do the job? 

One clip I saw on you tube shows a plastic bottle with meths+shellac flakes, throw in a blue sharpie pen and wait ......

If DIY route works, sky is your oyster, you could make blu/e any colour you want .


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## novocaine (20 Jan 2020)

gun blu (trademark) is a chemical oxide layer. it's not great in terms of abrasion resistance (or rusting to be honest). it's also known as black oxide. 

the term bluing isn't really true, it's really blacking but no one calls it that. search for blackening agent. you should be able to get it by the gallon. it's sellinium dioxide normally. (head and shoulders)


you can also do it with heat and oil but that depends on what you want to do, it's size and likelihood to warping or hardening due to heat. 

everyone else is talking about marking fluid. yes you can make your own with prusian blue and meths.

https://www.gaterosplating.co.uk/gp-coo ... acking-kit


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## AES (20 Jan 2020)

Thanks novocaine. You learn something every day - I really DID think he was talking about marking out (or something similar)!


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## HJC1972 (20 Jan 2020)

If we are talking about the same thing then Liberon used to sell a product called tourmaline that I used for ageing new brass furniture handles. IRC they stopped the product as it contains some pretty nasty stuff. 

There’s a company called Birchwood Casey that sell a similar product that works just as well. On brass it seems to work far better if you use it diluted in water and soak the product for longer. Also helps if the surface being blued is slightly abraded with a fine scotchbrite or similar. Jade oil (if you can find it) was the finish Liberon used to advise to protect the blued surface when finished. However, in the past, when I’ve restored split cane fishing rods I’ve always varnished the blued brass ferrules and they seem to have stood the test of time ok.


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## Phil Pascoe (20 Jan 2020)

Birchwood Casey make some brilliant stuff including TruOil.


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## ED65 (20 Jan 2020)

Munty Scruntfundle":9smvh457 said:


> I can only assume people in the UK aren't expected to blu anything larger than an M8 nut, unlike the people in the states who dunk their houses in the stuff and can order by the barrel!


Could you give us an idea of what you're doing as well as the scale of things you want to treat? Might lead to some further suggestions, i.e. to things other than cold-blueing solutions. If it's just firearms though 250ml should go a long, long way!




phil.p":9smvh457 said:


> Birchwood Casey make some brilliant stuff including TruOil.


Well they _market _some good stuff, not sure if they actually make much of it!


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## HJC1972 (20 Jan 2020)

ED65":3l62mjy1 said:


> Munty Scruntfundle":3l62mjy1 said:
> 
> 
> > 250ml should go a long, long way!




Yes indeed. Not sure how cold patinating fluid works on steel but certainly on brass I’ve found it to be counterproductive to use it in neatform. It certainly seems to react faster but the finish is fragile and much more easily rubbed off than when used diluted and slow.


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## Trevanion (20 Jan 2020)

It's more commonly known here as "Antiquing fluid" which you can buy by the five-litre drum from some places if you so desire, but it really is not cheap stuff! Americans tend to apply it neat because they're very impatient and expect instant results, it's supposed to be diluted 10% solution to 90% water which will grant two and a half litres from two hundred and fifty millilitres. Follow the instructions from the excellent John Penny Restoration site below and you'll work it out.

www.jpennyltd.co.uk/shopping/pgm-more_information.php?id=50


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## wallace (25 Jan 2020)

I use this stuff which is pretty good
https://www.frost.co.uk/extra-blue-blac ... t-1-litre/


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## chaoticbob (27 Jan 2020)

wallace":1vi60y21 said:


> I use this stuff which is pretty good
> https://www.frost.co.uk/extra-blue-blac ... t-1-litre/



This is interesting to me. Do you use the full 'kit' (alkaline degreaser, blacking fluid, de-watering oil) or just the blacking fluid? I can't imagine there's any special about the degreaser, but de-watering oil? Might WD40 work?
Bob.


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## marcros (28 Jan 2020)

wallace":2tbco2li said:


> I use this stuff which is pretty good
> https://www.frost.co.uk/extra-blue-blac ... t-1-litre/



will this work on stainless?


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## wallace (29 Jan 2020)

chaoticbob":17op56hz said:


> wallace":17op56hz said:
> 
> 
> > I use this stuff which is pretty good
> ...



I don't use the full kit, for best results I will wire wheel then degrease with clutch brake cleaner which is cheap £2.5O a can then dip in the solution then liberally spray with wd4O which I buy by the gallon.

I've not tried it on stainless Marcros.

I think they are basically all the same stuff the little bottles of gun blue and the stuff made by caswell which you add to water. I'm cheap and have found the frost stuff most cost affective.
I've seen black smiths using something similar on a program and they had a big gallon container of the stuff, but I tried finding it but couldn't.


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## marcros (29 Jan 2020)

the next time that you are using it on a restoration and have a spare stainless nut or bolt, would you mind trying it out?


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## sunnybob (29 Jan 2020)

I think youre on a loser.
I spent over 30 years heavily involved in guns made out of all types of metal and knew several people who cold blued steel guns, but none of them would touch stainless.

heres an article that might explain a bit.
https://shootingmystery.com/blue-stainl ... beginners/


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## marcros (29 Jan 2020)

I suspect so too. I dont believe that you can cold blue it, but whether all "blues" are the same, I dont know.


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## ED65 (29 Jan 2020)

I thought this would be the case, partly based on what I've seen of stainless in the gun world. Blueing relies on oxide being produced on the steel, and SS obviously is expressly intended to prevent the iron oxidising (the chrome does instead).

Krust doesn't work like most normal blackening solutions because it's producing iron tannate instead of magnetite. But the quality/uniformity of the colouring it produces might not be good enough for what you want.


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## novocaine (30 Jan 2020)

you can chemically black stainless steel. not with selinium dioxide though. oh no, SS needs fair worse chemicals than that. 

A hot bath of sodium hydroxide (caustic soda) and nitrites (secret blend of herbs and spices), at 285 °F (141 °C). sounds lovely.


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## marcros (30 Jan 2020)

I appreciate that it is way off topic, but is the blackening "parkerizing"?

Either way, I don't fancy that cocktail of chemicals at home.


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## novocaine (30 Jan 2020)

nope. parkerising is a zinc phosphate conversion. 

this is getting complicated.


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## marcros (30 Jan 2020)




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## Dalboy (6 Feb 2020)

Have you tried your local gunsmith or gun club as they may know where to get it.


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## sunnybob (6 Feb 2020)

https://www.brownells.co.uk/epages/UK.s ... ctID=49121


only needs a propane torch.


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