To Blue or not to blue a gun

A. The reason your blueing isn't looking "factory" is because gun manufacturers use a different type of finishing process. What you are doing is creating a depository coating commonly called "room temp black oxide". Gun manufacturers use "hot black oxide" to finish their products. Hot black oxide involves using boiling caustic (it boils at about 285 °F) and actually turns the steel black. Room temp blackening can be removed with a pencil eraser, whereas hot black is as durable as the steel because it is the steel. The blue color you see is because of the light refraction from the oil finish. My recommendation is to find a plating shop that offers hot black oxide finishing. Most shops have a minimum charge that should be pretty reasonable for a single firearm. Good Luck.

A. I've yet to find a good cold blue - i.e., durable - and I've tried a lot of them. Brownells' supposedly has a good cold blue ( Oxpho-Blue [affil links]) that I've not tried myself. You may want to check their website.

Brownell's also has a line of hot blue compounds that most good gunsmiths use, but again, I have not used them personally, so I can't recommend these. Problem is that hot blue is expensive for a single gun, and you need heated tanks. I'd recommend being happy with whatever cold blue seems to work best, or else bite the bullet and go to a gunsmith that does bluing.

A. Michel,

I have used Brownells Oxpho-Blue [affil links] and although it is good, it is still a cold blue. I do hot bluing and I don't think you will be happy with any cold blue process. It sounds like you have spent a lot of time on this but I think you will do best and be most pleased by finding a good gunsmith in your area who does hot bluing. Make sure you explain if you want a mirror finish when done as this depends on the finish of the metal before it is blued.

Good luck.

A. Bluing success or failure is determined by a number of factors. (1)Metal preparation: the surface quality, shine, polish or lack thereof will determine how your finished job looks. (2)Degreasing is important, yet so is removing any and all degreasing agents and (3) stop wasting time on cold blues unless you are going to do a "classic rust blue" and this is very time consuming to accomplish.

Brownells' products are very good, however I personally do not like Oxyaffnate 7.
as it is too temperamental, yet gives a quality blue. The Oxpho-Blue [affil links] is good and is great for touch up work.

You have invested a lot of time and money according to your info on an inferior product when it is more economical to set up to do a hot nitrate blue that will produce a superior and durable finish.

I've been at this for 30 years and have just a bit of experience.

A. My Dad's 1939 Chemical Rubber Handbook has a formula that I've used successfully on Steel parts. I think it contained Ammonium Poly Sulfide and is pretty foolproof for a transparent blue color. Sulfur displaces Oxygen so it prevents Rust and doesn't etch the surface. Basically a monolayer of Iron Pyrite (FeS2), so won't protect against acid.

A. Hi Gordon.

After spending that much for a custom gun, I can certainly understand how you would expect it to last more than 10 days, or at least to get a free re-work if it failed that soon. So I am not advising you against leaning on the gunsmith for a little compromise in view of your large expenditure with him, but I am telling you that bluing/black oxide has no corrosion resistance at all and it is only the wax or oil that you keep on it that resists rust. It must be lovingly waxed, oiled, or at least wiped with WD-40 [on eBay or Amazon] , very frequently, since it will rust as soon as the oil is gone. Good luck.

Regards,