doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Fireblueing How is it Done?

I find fireblueing to be a very attractive finish for small gun parts and screws. Does anyone on the forum have directions for doing this type of blueing?
Jim

I don't know if it is the same, but using propane, oxg/act, mapp and with the part being very clean and free of oil, grease and finger prints, is heated till it turns blue and then cooled by air.

You can get very close to getting this same effect, by using Oxpho Blue a few times and then buffing on a cotton wheel.

Nitre blueing I believe is what you want. You can achieve a number of color hues depending on the temperature of the molten nitre salts. This method gives excellent "peacock blue" or "fire blue" as well as the nice straw colors used on German Luger triggers and other parts, as well as other shades. It's an easy process, no problem at all to do it on your stove top with small parts. Brownells sells nitre salts in small quantities complete with instructions.

Tony Treadwell's book has a chapter on fireblueing. I tried it but it will really burn your finger when you put that propane torch on the screw you are holding!...Geo

Not sure if I am doing it correctly but, this is what I do.

1. Clean the screw
2. Tie a wire to it (acts as a handle)
3. Heat the screw with any torch until it just begins to change color
4. Drop it in oil.

That�s it. Maybe someone with more knowledge can tell me if I�m doing it right. Experiment with scrap to get a feel for how much to heat is needed.

Not sure if the type of oil is important. I have heard it should not have additives but I don't know. Castrol motor oil works for me.

I think traditional blacksmiths do something similar with linseed oil. They heat to about 400 F and wipe the oil on with rags.

I don't know the specifics of the old ways, but Brownells Nitre Bluing salts give a similar finish.
http://www.brownells.com/.aspx/pid=1105/Product/NITREBLUE-reg-BLUING-SALTS

I believe the spur and bit guys use it or similar to get this color when it was popular with them back about 10 yrs ago. Kinda like spinner wheels, the fire (nitre) blue spurs and bits have all but disappeared. Thankfully.

Standard chemical processes may be a better and more consistent way to blue small parts, but require a greater expenditure than does simple firebluing with a basic heat source. Using a propane/butane torch works for firebluing, but it is a delicate matter to reach the correct temperature without heating the parts too quickly and ending up with lighter blues and grays. If you heat past the correct color in this way, your only choice is to begin the process again.

A more controlled firebluing process that I now use is as follows: I polish the parts to the desired degree of luster, chemically clean them, then use fine steel wire to make hangers for the parts. I heat my kitchen oven to 570 degrees Fahrenheit (the correct temperature for deep blue, and one that my moderately old oven will reach), and I simply place an industrial thermometer on the rack and preheat the oven until I get the correct temperature. I hang the parts on the rack where the thermometer resides, close the door and watch until the parts move through the color range to deep blue. When the correct color is achieved, I simply remove the parts and let them air cool. I'm aware that some folks immediately quench the parts in oil or water, but I seem to get a good result without quenching. The color achieved lasts well, and can easily be redone if the bluing becomes worn over time. A good steel color chart that will guide your efforts can be seen at: http://www.smex.net.au/Reference/SteelColours.htm

Now that it has been simplified on a chart, where on that chart is the fire blue that the OP mentions? Am I to assume that the degree of polish is part of the formula?

If you just want a small quantity of blueing salts rather than the big lots sold by Brownells, check out the horological and clock making sites. These guys use the salts for bluing clock hands; I've seen some very handsome results.

I found that placing the polished, clean dry parts onto a brass plate and playing a gas torch underneath was easiest. When you get the right colour, I just flicked the part into a beaker of cold water, and followed up with de-watering oil.

Eug

I learned the process from my German gunsmith buddy, when I lived there. His process is exactly like RyanF's.Put the torch on the workbench or in the vise, and play the part in and out of the flame while watching the color. Quinch(?) when the desired color is reached.This is used for screws,pins,etc.,but Wallaceone's method is interesting for larger parts.
Mike