Can someone tell me the difference between cold bluing and hot bluing a barrel? Id like to get a chrome molly barrel matte blued, but dont know which way to do it. Thanks.

Scott,
there's a couple things..
1: "cold blue" is NOT a true blue... it always smells and it's always "wrong"
2: rust bluing could be called cold bluing, but incorrectly. it's where the barrel is actually RUSTED and then chemically changed from oxide to ox-something.. i think it's oxate, but I aint a chemist, Rob is. This is the BEST, but that's opinion

3: hotwater/express blue... uses, sometimes, the same chemicals as rust bluing (or not) and uses hot water to greatly accelerate the process. I like the color, but I have no idea of the durability, yet

4: HOT bluing.. this is a totally different process, using salts (remember, salts at basic/caustic, were 2 and 3 above use an acid). this is down around 300 degrees, with the barrel dunked into a tank of the stuff, and it reacts with the metal forming SOME change in the chemical structure, but it's not actually THE surface. It's kinds (in totaly layman terms, and again, wrong) a paint, as part of the salts combine with the metal, same as 1 above.

I have tried loads of cold blues, the best of that bunch is oxpho from brownells for color and lower oder. i have tried plum brown browning and belgium blue for hot water bluing, both with good results. remember, browning is just rust bluing, without boiling. I like the belgium blue for this.

hot bluing... I just farm this out, as I don't want anything to do with the tanks, right now. Caustic chemicals mean caustic burns, hot caustic mean bad news, and I don't like the smell

hope this helps, even though it's not 100% accurate

jeffe

If you want to do rust bluing, it's really simple and the "matte" look is simply a reflection of how much you polish, or unpolish as the case may be, your barrel before starting.

I have rust blued several barrels now using a homemade tank (rain guttering) and a couple camp stoves to boil with.

See www.winrest.com for a very good explanation and very good rust bluing solution.

This is so easy, no one should hire out to reblue a barrel.

Brent

Brent, thanks for that link, it has some good information.



I do not agree on the polishing and final finish on rust bluing though but we may be just talking semantics as far as a matte finish. I have started out with a high polish barrel and the acid will give a fine "etch" to the surface of the metal. The final look to it will no longer be a high gloss but there will be a shine. It will have an appearance of an extremely fine "frost" look to it but the high gloss polish is gone. If it isn't I suspect you have some problems either with your water or humidity or cleaning of the metal. But I suspect we are just talking degrees of what you consider a matte finish.



I live in an area where the humidity is very low and if I do not use a damp box and have the humidity just right, I can not get a good finish on the metal.

Customstox,
I do not get a high polish, but I don't like the matte look at all. Matte to me is that crap that looks like it was almost sandblasted. Also, I do not think the matte finish is conducive to maintaining a gun easily in bad conditions the roughness attracts grit and gives more surface for moisture and acids in ones perspiration, blood, tears, or whatever to do it's evil work. At least that's my experience.

That said, I have "polished" barrels to 400 grit and gotten the "flat" but not matte finish that most people I think would prefer. An honest 400 grit polish will probably satisfy most hunters.

The last barrel I polished to 1000 grit - knowing I would not maintain that that level of almost mirror finish. But I wanted to see what would happen. It ended up about the same as a 600 grit polish. Maybe a bit smoother, but not more than "semi gloss" if we can relate it to wood finishes. This is what I like personally, but I will not have to polish to 1000 grit to do it. This was just an experiment. I think an 800 finish, at most, is going to be plenty to reproduce the same final result that I got with the 1000 grit experiment. Perhaps I can even stop at 600 grit and not loose any further polish as I blue it from that point. But, I want just a bit more smoothness than 400.

I'm no expert, but I am learning. I rather like doing it too so that helps, and this gives me lots of practice as I gear up for my custom low wall .22.

As for the humidity thing, I built a sweat box but did not use it. Here is why. If you use a humidity box, you cannot leave that barrel in it more than a few hours. Maybe 4 hr tops. But given my life, I'm not awake that long, unless I'm gone. So, in my winter basement which is not real humid here in Iowa, I give the steel a coat in the morning before I leave for campus. I get back 10-12 hrs later and boil it. Then the next morning, I coat it again.

The humidity box just speeds things up. But you don't want to go too fast if you can't keep up your end of the argument. Rust never sleeps (or so says Neil).

Other suggestions, wash your barrel in the kitchen sink with real hot water and dish soap. Handle with dry paper towels only. This is all the degreasing you need. If you want though wipe down with a paper towel soaked in acetone or denatured alchohol.

If any cheap amature like me wants to do this, but doesn't want to pop for the big stainless tanks, I found that a 4 foot section of rain gutter with two endcaps attached with sheetmetal screws (IMPORTANT) and some gutter caulk to seal it. Works really well. Believe it or not.

Just my observations. Best of luck to everyone.

Brent

Brent, I am in agreement on most of what you said and as I suspected we are on the same page as far as what a matte finish is. The black ones that look like paint leave me cold. I take my parts to a 320 grit and I did not see any difference from those tothe one that had a high polish, but the acid I use may have some bearing on those results.



I use a commercial rust bluing agent called Gun Goddess and I watch the first two coats fairly carefully and after that I let it go 12 hours between coats. I have the humidity at 50% and the temp at 80 degrees. In my old damp box I used an electronic vaporizer for humidity control and it worked well also. The thing with any of these is to have control of the elements, temperature and humidity.



The other thing I find important is to have a small fan that moves the air around and makes the temperature uniform in the cabinet. Our humidity here is in the 20's in the winter and not a lot higher in the summer.



I like the idea of the drain pipe. That is very novel. I heard a while back about a guy who used a large piece of PVC pipe and hooked it up to the vent on a pressure cooker and with a closed piping system ran steam through the pipe to "cook" the parts. I understand it worked well also.



When I get my garage/shop cleaned I will take some photos of my bluing system and post them. I bought it from a custom gunmaker friend named Maurice Ottmar who was going out of the business for health reasons. He got it from the original owner in Portland Oregon who had the tank/cabinets built out of stainless by a Chicago Medical supply company. It is lavish to say the least. I also got a water still and tank, his damp box and his Carding wheel set up. One thing he did that makes sense is to take a small flat piece of metal approx. 1.5" x 6", drill holes in them and then cut threads for scope base screws, action screws etc. That way you can just leave them on the plate and use it to card them. Works great.



Grandview, I still swing a dead chcken over my head before I start. I get them at a neighborhood grocery store, 12 pieces for $5.99, all dark meat.

Chic, et. al.:

So, is it only possible to get the high gloss bluing ala the high end Sakos with hot blueing? If the rust blue doesn't take, or has blems, do you just re-polish and start over?

MKane160 aka BigDogMK