Fire bluing gunbarrels of old.

[jerrywh]

 Much false information has been spread on how this process was actually done in the early days of gun making. Also there were a tremendous amount of firearms in the colonies with barrels colored in like manner.  I cannot prove that any long rifles were as such but it is extremely likely.  Fire bluing is fragile and even the thousands of guns that were done so in the colonies never retained their original finish for long. Most guns with this finish were either high end European, English or trade guns for the Indians.
  I recently did a seminar on Bluing gun barrels chiefly on European flintlock guns.  I did research hand experiments on this for a year or so because I mainly do European stuff.  In researching the subject I was surprised to find illustrations of the process actually being done.  In this Book you will find engravings of the actual process being done.  It was done over a charcoal brazier  partially covered with a copper plate for heat dispersion.  It was also done in a huge pile of hot sand on a iron plate heated by a forge.  https://www.amazon.com/Diderot-Pictorial-Encyclopedia-Industry-Archives/dp/0486274292

[bob in the woods]

Interesting.  I always use hardwood charcoal for my fire bluing.   It seemed like the most likely colonial method to me.

[Long John]

Jerry,

I've seen some double guns with deeply blued barrels.  How do you think they kept the solder that holds the filler strips and ramrod pipes on from melting?  I guess they must have wired everything together.  But wouldn't that affect the finish color?

I found that book and ordered a copy.

Thanks for the info.

JMC
John Cholin

[jerrywh]

Jerry,

I've seen some double guns with deeply blued barrels.  How do you think they kept the solder that holds the filler strips and ramrod pipes on from melting?  I guess they must have wired everything together.  But wouldn't that affect the finish color?

I found that book and ordered a copy.

Thanks for the info.
    The double guns you see with fire blued barrels were brazed together with either brass or silver high temp solder as well as the ribs. That solder melts at 1250° minimum. No problem heat bluing with that.  The barrels were brazed in a furnace with the ribs in place as well as all the lugs , all at one time.
JMC
John Cholin

[Scota4570]

I do triggerguards and butplates, but only in a crude way, BBQ them and and plunge them into oil. 

I was thinking of using a possible better plan.  Take a steel loaf pan full of sand.  Put the parts in the sand and cook it on the BBQ until my infrared thermometer says 575.  Let cool, then oil or wax. 

Anyone tried such a scheme?

[jerrywh]

I do triggerguards and butplates, but only in a crude way, BBQ them and and plunge them into oil. 

I was thinking of using a possible better plan.  Take a steel loaf pan full of sand.  Put the parts in the sand and cook it on the BBQ until my infrared thermometer says 575.  Let cool, then oil or wax. 

Anyone tried such a scheme?

   Might work but the sand must be very clean. I use two different methods. I have a furnace with temp control from end to end. Pretty accurate but very slow and intensive. It has a ceramic glass top.  I also have heat and light dispersion and equalization set up in it. Sounds complicated but really isn't.  Dave Crisalli and another engineer gave me lots of advise on that.  The simplest way is Niter bath. I do not use potassium nitrate for the bath. Sodium nitrate is better as it has a lower melting point. We live in two different worlds as far as guns go. 

[Scota4570]

I have used potassium nitrate.   Made pretty bright blue parts.

It scares me though.  Intuitively I would expect that any combustable material that came incontact with the liquid salt would instantly explode.  Say a crumb or sawdust?  You are above the auto ignition point and the liquid is a powerfull oxidizer.  I definatly dont want to wear molten KN03.   

How clean is clean for the  sand?  Play sand?  Builders sand for cement work?  Glass beads?  Cook the sand first as a dry run?  If it were clean enough not to smoke, one could use the wife's cooking oven. 

[jerrywh]

I have used potassium nitrate.   Made pretty bright blue parts.

It scares me though.  Intuitively I would expect that any combustable material that came incontact with the liquid salt would instantly explode.  Say a crumb or sawdust?  You are above the auto ignition point and the liquid is a powerfull oxidizer.  I definatly dont want to wear molten KN03.   

How clean is clean for the  sand?  Play sand?  Builders sand for cement work?  Glass beads?

   I have a lot of experience at niter bluing. Something like a piece of sawdust will just float on top and burn up.  It is more like working with a lead pot. The biggest danger is water.  Just don't get any water around it. Even oil will just burn off.  But when you submerge anything it should be as sterile as can be so as to get the color correct. 

[T*O*F]

How clean is clean for the  sand?

The sand you need to use is white silica sandblasting sand.  It's specially cleaned and dried, but I think it only comes in 100 lb. bags.  You can't just find it anywhere.

[jerrywh]

 Clean sand like T*O*f* says. No dirt not moisture no wood particles etc. All that stuff makes irregularities in the color.