We quit bluing about 25 years ago due to my health. I have (greatly) missed not having a decent, durable coating since. Cold blue and fume bluing and heat blue are all pretty limited in what they can do and their durability.
About a year ago, I went on a new search for a finish.
Out of products that Brownell's carried, I picked Gun-Kote mostly because of what the techs at Brownell's said. I had tried all their "other" canned finishes. They worked somewhat, but with not very professional results. Then before purchasing the product, I started doing some online searching and got in touch with Wilson's smiths and a couple of other smiths. Gun-Kote was one of the highest rated finishes in the market place.
So I went straight to KG Coatings to find the reality of things. The owner has top notch ethics and believes that G-K is the greatest finish out there. I tend to agree, but my experience is less, so...
Anyway, I ended up with a cheapie blast cabinet. My compressor wouldn't even think of running it. New BIG compressor. The air lines were not up to what the cabinet and compressor needed. New copper air system with moisture traps and filters. I thought I was "done" except for a "simple" oven.
The oven ended up costing me $900. So much for "simple".
Then came trying some suggested spray guns as the cans will not give an even finish. Went through three guns (and a few regulators/filters) before I settled on the air brush that KG uses in house.
So I ended up with $7000 worth of system that should do it all. I did not take into account the learning curve of learning to spray. It ain't like spraying paint! It is more like spraying thin ink.
It has taken me a flat YEAR to start selling my output. I've done a few pieces for customers at no charge up to a couple of months ago.
Finishes available are "flat", "semigloss", and "gloss" in almost all colors. For guns, and in my opinion, flat is way superior. The semigloss looks somewhat "painted" to me. The KG guys say the gloss in many cases is even more "cheezy". There are many more colors available than anyone lists. If you want it, Gun-Kote will mix it! If a couple of folks want it, it is added to the line. But they don't even start to list all their colors.
When properly applied, Gun-Kote is from .0002 to .0005 of an inch thick. It passes military tests at over 500 hours of salt spray with NO corrosion. The dent impact flexibility is very high. Resistance to all chemical cleaners/chemicals is very high. (I left a puddle of high molarity sulphuric acid and another puddle of nitric acid on a piece overnight with no effect.)
The factory recommends knocking off sharp edges of parts to coat for maximum effect. However, I have about 30 pieces of cut off barrels and actions and such, all with sharp cut edges left, piled on a display case for customers to examine. Other than where I or customers have scraped one piece with another sharp edge repeatedly, there is no apparent wear. There is a parkerized piece and a couple of blued pieces laying with them. Their finishes are pretty trashed by the same handling.
If the piece is properly prepared and degreased and finish applied, I have yet to see a more durable or attractive finish. It *can* be abraided off. In fact, that is the only way you can remove it. But it withstands even abrasion very well.
I won't go through all the phases that my application went through to get the effects that I wanted. However, most folks do not experience that anyway, so maybe it's just me. Or maybe it's my standards. At any rate, I would suggest that anyone give it a try (with an airbrush). If you get it on well and baked well, you will have a great, durable finish.
Oh! One more suggestion. Do NOT trust your home oven thermostat for baking temps. The oven will likely do the job, though convection is MUCH better. Find a way to stuff a good thermometer like Brownell carries for bluing around the door seal. My oven uses a quality (home) oven thermostat and I have to constantly watch the thermometer and make adjustments. I'm in the process of remedying that. As far as an oven goes, you would be much better off with an oven from a yard sale that never again is used for cooking. The fumes are pretty nasty. I don't know if they will ever come out of the oven. Two of my customers have had to buy their wives new ovens after trying this. One is still getting away with it. This will limit you to handguns mostly, but that is the forum we are in.
For long guns, you will either need a commercial convection oven or build one as I did.
If I were to choose colors, I would limit things to Wilson Gray and Flat Black, but some of the others are nice also. I now have about 10 colors and add more on a monthly basis, but some of them can be finicky to coat and bake.
David