Re: Gun Blueing the Gas Tank
Ah, finally something I might know a little something about. Not an expert by any means with firearms but I have been an enthusiast and amateur gunsmith for years.
Some rambling thoughts: I don't know how well a clear coat will adhere to a true glossy bluing finish - and I sure as hell wouldn't want to sand it back a little to promote adhesion of the clear coat. A lot of guys will use wax over their blued parts when going out in the weather and it works well enough (same for wood gunstocks). But fighting rust will be an issue just like running a raw metal tank.
There are several types of bluing and similar finishes:
1. cold bluing, which both processes strat described are really considered,
2. hot caustic bluing (aka hot salt bluing), which is what you'll find on most blued commercial rifles and many customs,
3. traditional rust bluing is what a lot of home gunsmiths do and you'll find on really high end customs because it is very time intensive and looks beautiful. This can also be referred to as rust browning and is typical to the finish you'd see on old flintlock and similar style rifles.
4. parkerizing - is a rougher finish and usually has a charcoal, gray or sometimes gray-green tint but can get close to black and is what is seen on most military-type rifles like AR-15s. It also makes a great base-coat for a spray-on or spray-on and bake finishes like DuraCoat. [side note: Parkerize + Duracoat is what I typically use on my rifles, though my Dad has had two of his blued because he wanted a more classic look]
I believe someone explained that blueing is basically just rusting the piece but halting it at a certain point.
You could try cold blueing, or even cold blueing using heat as strat described to help get a better more even finish, and you may get decent results but it won't look like a true gun blueing. It's usually fine for small parts or to touch up spots. This is actually not a true blue or rusting process at all, it just uses a chemical process to color the metal.
I think parkerizing could be a good choice for something like this. It is really good rust inhibitor, but as anyone who has carried an M-16 through the bush for a few days knows you'll always have a trouble spot or two in creases and crevices. Plus it can be done at home easily enough. Places like Midway USA and Brownells sell the beginners kits. But it might be better to have the work done rather than spend $200 on something you may never use again. It won't be a beautiful finish but it will be durable. But if you like that type of finish this might work.
I don't know that a caustic blue would be a great choice. One reason is that because the hot temperatures of the blueing salts. Any silver solder will melt away, which is a problem with firearms. My tank has what looks to be some brazing(?) around the fuel cap area. I'm not sure if that would hold up or not. Plus this type of finish will be very, very nice and I don't know that I'd want that type of finish on my gas tank. I'd cry the first time it got marred in any way. But I guess it wouldn't be much different than a nice paint job though. As for holding up to fuel - good question, I'd ask a professional.
Maybe the best choice might be traditional rust blueing. It's true that you can create a show quality finish with a ton of work but you can also just do a few coats and create a nice finish and call it a day. This basically involves creating a box (or something that will hold in heat and moisture, though I've heard of guys just putting them in the trunk of their car) to hold the parts, a tin of water, and a fairly low heat source to allow the piece to rust for something like 24 hours. Once the part has developed a little fuzzy rust you boil it then card off the rust with a file card. The metal will start developing a blue/black coloring. Repeat the process until you're satisfied.
Don't take my word on any of the procedures, they're all from memory, do some research yourself.
If you're seriously interested in having something done or just finding out more information then I'd recommend contacting Mark Waldo from Blue Ridge Bluing (
http://www.blueridgebluing.com/). He has blued two of the rifles I built for my Dad. He does great work at a great price and he knows his stuff. I cannot recommend him enough.
