Wow! do you realize how deep and vague that question is?

The best bluing for the home gunsmith is the slow rust bluing process.

Well, might as well make it a 3 way split decision.

The best blue is a caustic hot blue, over a meticulous hand prep, no buffing.  

So, you now have the same choices you had before you asked the question.

1) Cold blue
2) Home craftsman slow rust blue
3) Professional hot caustic blue.

All 3 have their place.  The real question to ask is "what would you recommend, in my circumstances?"  After you described what you are trying to blue, what you want it to look like when done, and what your skills and resources are.  Then, we could put together a meaningful recommendation.


I'll make a stab at the 3 options, presuming you're wanting to blue a rifle.  

Cold blue it if you just want it to be vaguely gun finish like, and want to do it the easiest and cheapest way possible.  Follow that up with a linseed oil finish and some wax and it will last for awhile with some careful care.  Expect to invest about $15 in the process.  Oxpho blue is generally recommended as the best, but I'm not sold on that, a lot of that is loyalty to the old Brownells and their good instructions that they included with the solution.

Slow rust blue it at home yourself if you have the skills to clean up the metal finish yourself and take it to a perfect 400 grit finish.  Know that you will have to make a steam pipe to convert the rust to blue, and will have to commit 2 to 3 days to the process, an hour at a time, 3 to 4 times a day.  Expect to invest about $50 to $150 in the process, depending on how much of the steam apparatus you have and/or scavenge.  If you're meticulous, you can easily equal the best professional work after 2 or 3 projects.  You're first one will come out okay, if you don't hesitate to refinish and start over if it gets botched up.

Send it out to a professional to either rust blue or caustic hot blue it if you don't have the skills, space and patience to do a slow rust blue yourself.

If you just want it to be durable and blued, send it to a buff and blue place and let them do their magic for $200 or less.  Or add another $100 to $150 for a decent hand polish.

If you want it to be a show piece and highly durable, send it to someone who will meticulously hand polish it and take the time to rust blue it well, with about 8 to 12 passes.  Expect $250 to $600, depending on complexity.

Dave,
Looks like we were both responding, good info too.
Greg

Machine or Carbonia bluing.

I've used Brownell's dircropan IM with good results.  It's a hot water blue similar to using the Herters blue as mentioned above. It's a fast rust blue by boiling and applying the product and carding with steel wool multiple times. Relatively durable, maybe not as durable as hot salt bluing, but almost.