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

I've been following this thread, so I had to give heat bluing a try. I watched two videos by Larry Potterfield, one titled Flame Blue (), and the other titled Nitre Bluing (). Using equipment on hand (torch, hemostats, motor oil for quenching), I tried it on a couple of cheap machine screws, and here is the result:

I'm satisfied with the results given that this was a first try. I expect I could do better with more practice. My biggest challenge was catching the color change where I wanted it. The screws heated up so fast that when the color change started to happen it was hard to get them into the quench fast enough. Again, with practice and patience I could do a little better.

A couple of things I'd welcome input on - when doing this with heat is the durability of the finish any different than doing it with nitre salts? Similarly, what is the overall durability of the finish? I realize it polishes off easily. Does the finish bring any additional rust protection? Any input is appreciated.

“ A couple of things I'd welcome input on - when doing this with heat is the durability of the finish any different than doing it with nitre salts? Similarly, what is the overall durability of the finish? I realize it polishes off easily. Does the finish bring any additional rust protection? Any input is appreciated.”

The coloring is not durable.

There’s no difference in the colorings durability done with either salts or flame. It’s still coloring done by heat. Salts just heat up and surround the steel in a constant temp bath. Whether you accomplish it by using a flame or salts, all your doing with either method is heating the steel to bring out a particular color whether that be straw/yellow, purple to various shades of blue to black and even gray.

It provides no real rust protection because the coloring doesn’t hold oils like blacking does.

One trade trick when using a flame is to heat the pin or screw from the bottom up. It allows the pin/screw to heat more uniformly. Don’t apply the flame directly to the steel, move the steel in and out of the flame and go slowly.
The higher the polish, the better the color.

The method that works for me for torch bluing small screws is to use a piece of thin, no thicker than .125, brass, drill holes in the brass stock for the screws to pass through, then heat the brass with the torch. The heat goes through the brass to the screws and the color change happens slower so easier to control. When the desired colored is reached just dip into water to stop the change.

For larger screws I have a small can of chips from the lathe and lay the screws on the chips and heat the can from the bottom.

The last screw I heat blued was some 20 years ago. It is the top tang screw on the last m/l roundball rifle I built. I browned the barrel/breech/tang, but I wanted to see how a blued screw would look in the tang. It worked perfectly, gave a fairly bright blue, and has held up fine for all these years. No loss of color.

This is the video referenced in the original post (sorry I started with the last post and didn't realize the video was brought up earlier- thus the edit). It's a very similar method and described by Cold1.

Not gun related, but you might find all of the clickspring videos interesting.