a black powder question

[Turtle]

  has anyone ever tested black powder performance as related to it's moisture content? Since it readily absorbs moisture, it seem like that would a common factor. I have had unexplained accuracy issues with powder in my horn for a long time ,and put in new from a can and it helped---not a scientific test. How do you all address this issue/
                                               Thanks, keep your powder dry,Turtle

[hanshi]

It is my understanding that black powder absorbs no really significant amounts of moisture; the fouling does, however.  It has been mentioned by those who are more familiar with the subject, that potassium nitrate that is not of best quality - contains sodium, say - will attract moisture.  I believe that the powders now available to us are made with high quality ingredients.  Perhaps something about the horn is the cause.

[Turtle]

 so what I read about black powder being highly hydroscopic is false? I hope so and I'll quit worrying about it.

[EC121]

BP fouling is seriously hygroscopic, but unburned powder is pretty stable.  I've seen days in Alabama where the pan would fill up with water between shots.  I would wipe the pan and prime, and the main charge would work just fine.

[Turtle]

then why does my pan of 3f turn to gue in humid weather?

[rich pierce]

The fouling is what gets muddy.

[EC121]

then why does my pan of 3f turn to gue in humid weather?

If you mean the lock pan, it is probably the fouling under the 3f getting things started.  It only takes a thin layer to draw moisture.  The pan would  have to be clean and bone dry not to get wet in humid weather.  Might try putting some powder on a piece of aluminum foil and setting it on the table to see if it gets wet.  On a really humid day after some time, it still might get wet.

[Semisane]

Summer here in Louisiana I absolutely must wipe the pan after each shot. Otherwise it will look like the D.C. swamp by the time I get a fresh load in the barrel.

[Standing Bear]

My theory is that the relatively fast seating of a ball pushing a large volume of damp air thru the touch hole (a venturi) drops the pressure and temperature (as in a refrigeration unit). Look at the pan before seating the ball and again just after.

[Turtle]

 The BP in the pan of my unfired gun gets muddy when hunting-no fouling present-so BP must absorb moisture easily. What am I missing here?

[rich pierce]

The BP in the pan of my unfired gun gets muddy when hunting-no fouling present-so BP must absorb moisture easily. What am I missing here?

Well in that case, you’re not missing a thing.  Your powder is absorbing moisture all right.

[Daryl]

BP fouling is seriously hygroscopic, but unburned powder is pretty stable.  I've seen days in Alabama where the pan would fill up with water between shots.  I would wipe the pan and prime, and the main charge would work just fine.

"Wikipedia"

"The similar-sounding but unrelated word hydroscopic is sometimes used in error for hygroscopic. A hydroscope is an optical device used for making observations deep under water."

[PPatch]

The BP in the pan of my unfired gun gets muddy when hunting-no fouling present-so BP must absorb moisture easily. What am I missing here?

If you are priming with FFFFg try FFFg, or even FFg if that is what you happen to be shooting in the gun.

dave

[Turtle]

 thanks ppatch, but I already use 3f. I did find 4f I used to use sucked moisture like crazy. Getting back to my original question- does moisture content affect burning properties and therefore accuracy?

[PPatch]

Turtle what brand of powder are you using?

dave

[Turtle]

GOEX

[Craig Wilcox]

Many of the synthetic black powders are indeed hygroscopic.  They contain perchlorates, which have a natural affinity (hygroscopic!) for water.  Yeah, they are easier to clean, but if you forget for even a little while, be careful.

[Darkhorse]

I live in south-central Georgia and it doesn't get anymore humid than it does here. That being said I use 4f goex for all my priming, hunting or practice, with no problems. On two occasions I did have the liquifying effect described here, once it was because the lube I was using became almost liquid in the heat and the liquid came out the touch hole. The second time was the lock lubricant migrated enough to wet and slop the prime.  Both issues were easy to fix. And I now use just a touch of lube inside my locks.
Before I go to shoot or hunt I wipe the bore with a clean patch, then again with one soaked in alcohol, I also wipe the pan area and on and under the frizzen with alcohol. When hunting I check my prime regularly and it's always good and dry, ready for a shot.  Never a wet muddy mess.
When just shooting I occasionally wipe the pan with a patch, sometimes moistened, then back to shooting.
I just don't have the problems I see described here so I think one must look farther than just the prime being used.

[Mad Monk]

  has anyone ever tested black powder performance as related to it's moisture content? Since it readily absorbs moisture, it seem like that would a common factor. I have had unexplained accuracy issues with powder in my horn for a long time ,and put in new from a can and it helped---not a scientific test. How do you all address this issue/
                                               Thanks, keep your powder dry,Turtle

I put about 20 years of lab work and shooting into this subject.
The hygroscopic properties of black powder will vary from lot to lot and brand to brand at times.  A PROPERLY prepared black powder is nearly non-hygroscopic. The degrre of affinity for moisture from the air depends on the purity of the potassium nitrate and the ash content of the charcoal used in the powder.  Most of the comments out there on black powder being highly hygroscopic came from the days when the old GOEX corporation  was making black powder at the now abandoned Moosic, PA powder plant previously owned and operated by Du Pont.  When at that plant GOEX used potassium nitrate out of Vicksburg Chemical Company at Vicksburg Mississippi.  And it was in fact a fertilizer grade and not a 99.5% pure technical grade.  It contained 0.5% sodium nitrate.  Sodium nitrate is deliquescent.  That means it will draw enough moisture from the air to turn into a liquid.  Way beyond what would be called hygroscopic.  Then their charcoal ran as high as 15% ash content.  Maple wood charred with the bark still on it.  The so-called ash was mainly potassium carbonate, or potash.  At high humidity it is  deliquescent rather than hygroscopic.

While I have not looked at GOEX since Hodgdon took over I know that the potassium nitrate they now use is a fairly high purity product out of Chile.  No where near as hygroscopic as the old Moosic GOEX.

Most BP manufacturers dry the powder down to around 0.5% moisture before packaging.

Pan powder in a flintlock.  The use of 4Fg is questionable.  The initial pick up of moisture, from the air, involves only the surfaces of the powder grains.  4Fg is generally screening process "tailings" and does not represent a specific grain size distribution. 3Fg will work just as well and has a lot less surface area to pick up moisture.

Storage between shooting days.  As you use powder from the can or bottle you let in air.  If the air is moist the powder will pick up a bit.  Then you open the can or bottle again and allow fresh air into it with still more moisture.  If the caps are not real tight the can or bottle will "breathe" with changes in atmospheric pressure.  Another source of moisture.

With the brands of black powder on the market today all are far better than the old Moosic GOEX when it comes to moisture problems.

Main charge powders.  You see little effect by moisture in the powder as long as the moisture content is less than 1%.  Once the moisture content of the powder starts to go above 1% you then see drops in muzzle velocities and increased bore fouling as a result.  When you get up around, or above, 1.5% moisture content the velocities really start to drop off.  Ignition is slowed a good bit.  This will usually give vertical stringing on a target.

Bill K