I've never tried it before but took the plunge last week. Had a nice sidelock action to tidy up and thought I'd have a go at the screws and pins.
I'd bought some charcoal blueing salts from Peter Dyson (UK) a while back but not had a chance to use them.
The instructions seemed a bit short, but on reflection, they told me all I needed to know.
Most pins were on the bench but I opted to remove the ones from the locks one at a time as I didn't want to mix them up.
A quick polish on the mops first, then into a caustic soda solution to thoroughly degrease the parts and remove any polishing compound was all the preparation needed.
I tipped the powder into a stainless container and heated it over a small camping stove.when the powder turns to clear liquid, it's apparently at the right temp to work so after a rinse and dry, the first screw or pin was dipped into the molten solution and as you watch, it turns straw yellow, then red to purple and then to a lovely dark blue, at this point, the part needs quenching in water followed by a quick drying with paper towels and I dropped them in de-watering oil.
I was surprised by how easy it is to achieve really good results, admittedly, I had to repeat the process on a couple of parts as I'd held them in the solution too long and they'd gone from blue to grey, a quick polish and degrease is all that was needed before popping them back in until they were the correct colour.
A word of caution, the salts are heated to 400'C so are very hot, keep water, hands and eyes well away. I used long tweezers for the first couple of parts but soon decided to hold the tweezers with pliers as the heat made my gloves too hot . Eye protection is an absolute must aswell.
The results were really good so if you've never tried it but thought about trying, give it a go, it's one of those little jobs that can make a gun look just that little bit better.

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I re-did a couple of those pins after I saw the colours. The heads inside were nice and blue but it didn't look good with purple ends in the lockplate.

They look good. Was there any mention on the package as to what the contents were? I had also wanted to Nitre some screws and a trigger guard. The screws were easy, the trigger guard I did not spend enough time polishing and it came out dull which it what I expected.
I used a product sold in Lowe's, it is a stump remover. I forget the exact ingredients, but the temperature is like yours. It is opaque and then turns clear. Never get any water near it and I used elbow length gloves, glasses with a face shield.

http://www.brownells.com/gunsmith-tools-...s-prod1105.aspx

Hi David, there's a data download at the foot of the page with content percentages..
It's potassium nitrate, sodium nitrate and sodium nitrite.
Always thought it was just saltpetre but maybe the sodium compounds stabilise the mixture or give more vivid colours.

Is nitre blue on the pins and other parts a British fashion or is it also continental?

El Garro, thanks for the link. I will look at the container I have of the stump remover and see what percentage it has.

Old Colonel, to be honest I don't know enough about continental guns to answer that. When I look at the big picture I still don't know that much about British guns either but I'm learning more every day.
Maybe someone in the know will be along to give some information soon.

David, that's a nice set up you have there. Mine is more akin to the kit that people use to cook their bacon and eggs on by their tents
I'm guessing the Brownells mix would be similar to the one I bought here in the UK but couldn't say for certain.

I believe the Spanish did it as well.

http://horologyzone.com/watch/watch-school/bluing-method-1.html

Horologists (clock and watch makers/enthusiasts) blueing salts appear to be widely available at affordable prices.
The link covers 3 methods used to blue small parts but the bit I found most interesting was a very good explanation as to how and why the different colours appear.
It's certainly worth a look,

That was interesting to read, thanks for the link.

Oscar used to say that Brownells stuff would not nitre blue but just gave heat colors. His bath used the traditional KNO3 and a bit of aluminum sulfate. If you see colors you get with a torch you have heat blueing not nitre blue.

bill

Anyone have an idea on how much aluminum sulfate to add to the KNO3?

Sorry, he said he just put a small amount in the bath. He never gave me a ratio or anything positive. It was a small percent but he just dumped.

Bill

Bill, I believe that Oscar used Manganese Dioxide, at least that is what he told me to get. I bought the scientific grade as he told me to do and I used a VERY small amount - maybe 1/10 of a percent- probably less than that. It is simply and additional oxidizer and is probably not needed.

Doug

I don't know why Oscar disliked the Brownells Nitre salts,,but he really had it in for them, or for Brownells.

I've found the salts to work just fine. You can also boost the temp to 850/875F and get a deep blue-black also, just as with Sodium or Potassium Nitrate.

Most any metalic salt can be used. It melts and is reasonably clear so you can see the part(s) in the stuff.
The temp does the bluing w/o the atmosphere O2 interfering.
You can use molten lead too as long as you get it to the right temp.

Manganese Dioxide is mentioned in the original Winchester write-up recipe for Nitre bluing as an added ingredient.
The hand written notes are shown in Midas' book on Winchesters,,if you have a copy of that.
I don't recall the %, or if it even says how much.

Others much smarter than I have said it was to lower the melting point of the concoction once mixed.
I guess that'd make sense if you wanted to use it for different tempering levels and colors.
I don't know.

I've just used straight Sodium Nitrate, Potasium Nitrate, even Ammonium Nitrate in the past and gotten the desired results.
The Brownells salts works fine for me now.

I still use lead to draw the temper on springs.

Be careful with any of this stuff,,eye, face and cover gear a necessity. Use a sturdy set up,& keep the kids and pets away.

Doug's got it. Just a pinch of MnO2. It acts as an oxidation initiator as I recall Oscar indicating.