doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Charcoal bluing

I used to have a low temperature salt setup that was roughly 10 inches deep, and use some stump killer grade potassium nitrate on and off in a different setup. I�d leave a smooth steel rod in it for cooling, a little torch heat on the rod would let it wiggle out of the solid block, leaving a vent hole for reheating.

I just wear full leather welding gear and a full face shield around the stuff when it�s warmed up, no big deal. It doesn�t do unpredictable things. I made a little three hole rack that I could adjust a stop depth on, best control and simplicity for me to anneal rifle brass.

PNO3 ????

I have never heard of Phosphorus Nitrate. If such a chemical existed, it might provide glow-in-the-dark bluing! You learn something new here everyday. Sometimes the thing you learn is that some people who think they are brilliant... really are not.

Seriously...you want to belittle the posts that Kutter provided just because of a typo PN03 instead of KN03 for Potassium Nitrate?

I really enjoy the learning opportunities this site provides from the professionals that contribute.

Not sure of any history here but the comment seem a little over the top.

Scott

DGJ: 98% gold; 2% childish nonsense. I've decided the gold is worth it, but it does get tiresome.

The comment was not directed at Kutter. He did NOT make the error.

DM-You are correct.

Keith-Mea Culpa. I do enjoy the gunsmthing advice you give.

Scott

Some very good points from Kutter, Brent and others. One more thing to never do, with lead ........ if you leave a substantial amount of lead in your pot to cool down and solidify. Next time you heat it back up the lead will begin to melt at the bottom. There will be a layer of solidified lead on the surface that will lead you to wonder if your pot is getting hot enough. It will be the last to melt. Never use an object to break that crust to "hurry things along". I once did, using a sharp, pointed awl. When the point broke through the crust a geyser of molten lead spewed upwards out of the hole made by the awl. Only because of a quick reaction did I narrowly escape a serious burn. Lesson learned .......... patience is a virtue. From what keith wrote it sounds as if this same thing could happen with nitrates.

Great idea of Craig's about the steel rod.

Best, SRH

If I remember correctly, I picked up some Gordon's Stump killer. There were two varieties of Gordon's, one indicated it was 100% pure Potassium Nitrate, the other was Potassium Nitrate with some other ingredients. I used the 100% Gordon's. It seemed to work well on some pins and a trigger guard I nitre blued.

I used a propane burner a stainless pot I picked up at goodwill and a BBQ thermometer that registered 700 degrees. My thought at the time was I need to pick up a better thermometer that registers a bit higher temp.

A bit of a learning curve and I didn't do enough nitre bluing to gain good consistent results for the fire blue I was attempting to get. I did get some nice blue and blacks but it was inconsistent!

Get a Lyman casting thermometer. They are quite inexpensive and very functional.

Inspired by PhysDoc's experiments in charcoal bluing, I thought I would try mimicking it in a lead pot. This thread makes the process sound like it is totally temperature driven and not a chemical process like rust bluing. That begs the question, exactly what IS the chemical nature of charcoal blue, but I skipped past that to try the lead pot.

In my 20# Waage pot, I normally cast at 800 F (measured with a Lyman casting thermometer). Its thermostat is nearly maxed out at that temp, but I was worried about getting into forbidden territory above 900F so, I figured it might suffice. I set up in the driveway to be a little safer with fumes.

The pot got to just under 900F. About 880F or a titch higher. That's as high as I was willing to go.

I had two pieces of dovetail filler bar that I had polished quickly to 1000 grit. I cleaned those in Acetone and deliberately placed a finger print on each of them.

I wired the pieces to some soft iron wire and sunk them in the pot. This could have been thought out a bit better, but it worked.

After 10 minutes, I pulled one piece. As it came up through the surface, it collected some dross that did not shake off or knock off as I anticipated (as lead will flake off a mould's sprue plate). I fetched a wire brush, but it would not rub off very well either by that point. I plunged it back in the pot with the first piece still in there. At the 20 minute mark, I pulled both, but this time I carefully cleared the surface of the lead first and I immediately rubbed the parts down with the brush. This worked much better, but far from good. I would not want a whole action to deal with like this.

Overall, the color was not a deep black but rather a shallow very dark grey/blue. Somewhat mottled and definitely think. It was close, and it was rather attractive, but it was not what I had hoped for. The 1000 grit shine held up pretty well however. There was no trace of either finger print. Both parts were about the same, as the first one was when pulled the at the 10 minute mark. Therefore, I don't think more time is the solution.

In conclusion, I think 880F is not hot enough. Hotter is not a viable solution using lead. The dross problem is another issue.

Perhaps nitre salts would get hot enough and work perfectly, but I suspect there is more to this than heat and that's why they used charcoal in the old days.

Anyway, I hope someone else decides to experiment and finds better results. I'm looking at my grills and wondering how I could make this work.