Low-shrapnel priming flask

[Canute Rex]

After reading the latest about an exploding horn, I thought I'd like to have a priming flask that isn't a potential fragmentation grenade. I decided to use cuir boulli - boiled leather. It's pre-petroleum thermoplastic. There's a bit of art to it, but really it's just immersing veg-tan leather in hot (~180F) water for a minute or so.

I made a pear shaped pattern with ears for suspension, 4" x 2 1/2", cut out some veg tan 6 ounce (?) and sewed it together. Then I soaked it in water and worked a brass air fitting into it. Why an air fitting? Convenient shape and - it's an air fitting. I temporarily bound it in place with waxed thread.



A little compressed air from the tank and it bellied out nicely. Then I heated up the water and held it under for something approaching two minutes.



It ended up looking like this.





The leather shrunk 5% or so, which locked in the air fitting. I put a permanent waxed thread binder on it and dyed the thing black. Then I beeswaxed the seam and put some Red Wing boot sealer on it.

I chucked a piece of 1/2" brass rod in the drill press and drilled and  filed out a cap, and filed off the ridge on the fitting. Braided some waxed hemp for the cord and made a sliding keeper for the cap.







I'm hoping that it never goes off, of course, but if it does the leather will go "blap." Burns but no shrapnel.

[Jerry V Lape]

When you sewed the leather edges, did you apply any mastic or sealer to make the shape air tight?  If not, what makes the seam tight enough to avoid exposure of the content to flashes from firing?   Approximately how much air pressure was applied to bell the leather out? 

[LRB]

  Jerry, I think his object in mind was to prevent metal, bone, or other hard material from becoming shrapnel particles in the event of an explosion while priming the pan. I have never heard of such ever happening, even historically. The possibility would have to be on the lowest level of remote, to near zero, so it is my opinion that he has merely made a very fine looking primer of hardened leather, with excellent workmanship, and leather skills.

[Hungry Horse]

 This is not as remote as some may think. The main reason for old powder flasks being made from thin brass, and copper, with a soft solder seams was precisely  this danger. The very modern, and quite popular, tubular powder flasks, made from heavy brass tubing,with threaded end caps, are a hand grenade, in my opinion.
 Although I haven't seen any old examples of jacked leather powder containers, I'm sure they existed. Jacked leather was boiled, as you have done. The outside was coated with some sort of varnish, or shellac, while the inside was often coated with a substance called brewers pitch. Most items made from jacked leather were intended to hold liquids, not repel them. So, quite possibly you could simply varnish, or shellac, the inside, and outside, and be done with it.

                        Hungry Horse

[Jerry V Lape]

LRB,  I really like his solution of making a primer which shouldn't produce shards in the event of accidental ignition of the contents.  However, we do know of several instances of horns exploding (there is one posted under black powder shooting right now) and I know of another.  There has also been discussed the little brass primers with the push tip going off.  The issue as I see it is protecting the horn or primer throughout the shooting activity, not just while priming.  If a crack in a horn is enough access to flash as discussed in the shooting subjects, a gap between the edges of the leather would not be a great thing either.  I just wanted to learn as much as I could before attempting a similar primer.  

[Canute Rex]

Hi Jerry,

No mastic or glue. When the leather hardens in the hot water it also shrinks and thickens. The thread shrinks a bit lengthwise, I think. Anyway, the result is that the seam tightens up. I rubbed and melted beeswax into the seam, but I'm thinking that's not so much necessary for keeping powder in and sparks out as for waterproofing.

For the life of me I couldn't tell you the air pressure in the flask. "Enough." The tank was at about 100 PSI when I charged it, but I just barely cracked the valve enough to get the leather to inflate. The air was hissing out all around the seam. The bubbles in the second picture aren't the water boiling. The leather is still kind of soft when it comes out of the water, but as it cools and dries it hardens up.

LRB, thanks for the compliments - black dye covers a host of sins. I am quite pleased with the way the cap came out, though.

The other thing I wanted to accomplish was to have a priming flask with a cap/plug that I can't lose, but that I can work with one hand. With the flask hanging around my neck I can pull up the cap and the roughness of the braided cord holds it up. When I'm done priming I can slide it back down and the outward pull of the two cords, plus a little friction, keeps it in place.

If you look at the next to last photo you can see that the inside of the cap is countersunk to match the angle of the spout shoulder. I figure that will help to keep water out in messy conditions.

I'd recommend some experimentation with cuir boulli to anyone. It isn't difficult and the resulting material is versatile and durable. I even made my sister a Kindle cover out of it. The main thing is to have something for a form. In this case it was compressed air pushing out. In the past I have used pieces of wood heavily coated with paraffin wax.

[The Original Griz]

Rex, do you sell these? I am interested if you do

[bigsmoke]

In years gone by, I used to make ball/shot flasks that looked exactly like your little powder flask.  I had thought occassionally about using compressed air to balloon out the leather sides, but did not know if it would work.  Evidently it does.  I used #5 nickle plated shot and cramed it inside the flask until it was the shape I wanted.
Rather than doing the 180 degree water bath, I would just run hot tap water into a sink and toss in a dozen or so sewn flask bodies and leave them soak for a few minutes.  I built a little spreader device to open up the mouth of the flask, ran a piece of dowel into the flask and then ran hot tap water into the inside.  Then started packing the bb's.
For a ball flask, I used a piece of 3/4" thin wall copper pipe in the mouth of the flask.  I belled it and used a piece of 7/8 dowel tapered down for a stopper.  For shot flasks, I used a short length of 3/4" copper pipe silver soldered onto the base of a English or Irish shot flask.
I have no idea how many of those I made over the years, but to say hundreds might be understating it a bit.
Anyway, I sure wish I would have continued on with the thought of using compressed air.  Might have saved myself a lot of time and trouble.  Good idea.
John