BP shelf life

[Mumbles]

My experience has been that if you set things out directly into the sun to dry they have a tendency to get driven in. This is more for stars than BP. My opinion is that BP is too small of granules to be affected by that. The recrystallization of nitrate may be an issue due to the increased temperature, but it still performs fine for me.

 

I tend to dry stars in the shade with a breeze for a few days initially to get rid of a bulk of the water. After this, putting them in the sun or a drying box to finish them off has never been an issue for me personally. I don't do this for glitters though. I wouldn't want to tempt a reaction.

 

These are just my own personal experiences. Maybe I'm doing it wrong, but so far so good.

[rogeryermaw]

the issue with recrystallization for me has only occurred with serious over wetting. with only an ounce or so of water to wet almost half a pound of b.p., very little KNO3 will dissolve.

[dagabu]

the issue with recrystallization for me has only occurred with serious over wetting. with only an ounce or so of water to wet almost half a pound of b.p., very little KNO3 will dissolve.

 

Agreed, if adding too much water, granulate, dry for an hour, make a ball again and try the granulation a second time. It's a good way to save it from growing crystals.

[taiwanluthiers]

I heard of horror stories of bp autoigniting in the sun... what are the chances of this?

[rogeryermaw]

all it takes is poor placement under a drop of water that magnifies the sun....

 

i've seen fires start this way.

Edited September 4, 2014 by rogeryermaw

[dagabu]

Stainless steels bowls (parabola) seem to be the culprit, never heard of drying screens going up in China due to just the sun.

[wildcherryxoxo]

Mike swisher said dry in the sun for 20-30 minutes, put through the screen again, and then dry in the shade as normal.

 

In the case of stars, I don't believe he (or anyone) advises direct sunlight.

 

In one case, chlorate stars dried in the sunlight ignited on handling. (Breaking apart 2 stars that say too close) direct sunlight was the proposed culprit.

[dagabu]

Mike swisher said dry in the sun for 20-30 minutes, put through the screen again, and then dry in the shade as normal.

 

In the case of stars, I don't believe he (or anyone) advises direct sunlight.

 

In one case, chlorate stars dried in the sunlight ignited on handling. (Breaking apart 2 stars that say too close) direct sunlight was the proposed culprit.

 

"Even the venerable Mike Swisher quotes Landcaster just this week saying to lay the fresh pulverone out in the sun to skin over and re-screen." Isn't that what I just said?

[Mumbles]

Dag, I believe there is a distinction to be made here. What you both pointed out is that Mr. Swisher recommended to dry the polverone in the sun for a short period of time to dry out the surface before the final re-granulation. Wildcherry simply added and clarified that after this, the polverone was allowed to dry in a shady dry place out of direct sunlight.

 

The sun is only used for a short period of time. The actual drying takes place in the shade or inside a building. No one is going to argue that exposing wet composition to brief sunlight is going to automatically drive them in.

[dagabu]

I did leave that out, gotta work on getting the complete thought down before closing up shop.

[rogeryermaw]

is the benefit of the short drying period in the sun to speed up the sorting process? after granulating, i just set mine out single layer on cookie trays and leave them out in an air conditioned workshop. after 24-36 hours it's completely dry.

[Merlin]

This had diverted to drying stars in the sun? I am surprised no one has commented on Skylighter's suggestion to dry suspected wet BP in the kitchen oven!

Whatever method I use for granulating from now on I will coat in graphite and store in air tight container with a bag of drierite.

[dagabu]

This had diverted to drying stars in the sun? I am surprised no one has commented on Skylighter's suggestion to dry suspected wet BP in the kitchen oven!

Whatever method I use for granulating from now on I will coat in graphite and store in air tight container with a bag of drierite.

 

Why graphite?

[rogeryermaw]

This had diverted to drying stars in the sun? I am surprised no one has commented on Skylighter's suggestion to dry suspected wet BP in the kitchen oven!

Whatever method I use for granulating from now on I will coat in graphite and store in air tight container with a bag of drierite.

no sir really we were discussing drying black powder in the sun and why or why not it may be a good idea to do so. as far as drying and pyro comp in the oven? yeah...eff that!! there are far easier ways to kill oneself.

Edited September 4, 2014 by rogeryermaw

[BurritoBandito]

 

Drying in the sun has always caused either driven in stars, or crystallized potassium nitrate. It's best to dry everything out of direct sunlight.

Always? Not that I've experienced.

Dry it in the sun and re-mill if needed.

This is BP not stars. It is not going to be driven in, and remilling would rectify the recrystallization of KNO3.

Merlin, I second the idea of drying and remilling (if necessary). I doubt much KNO3 will recrystalize with the small amount of moisture that is likely to be present. Dry it, test it, and if it's not up to par throw it back in the mill. Once you get a decent powder seal it up in an airtight container. If the problem is found to truly be moisture, store it with some desiccant.

[Merlin]

The reason I am coating in graphite is because Goex is coated in graphite and it always works as intended.

[BurritoBandito]

I very well may be wrong, but I believe the graphites purpose is to reduce static sensitivity.

[rogeryermaw]

they use graphite to improve the appearance. after the powder is granulated, they roll it with graphite to coat and round off the sharp edges of the grains. the graphite actually slows the burn rate a little. graphite is also conductive and may make powder even more static sensitive...that part is speculation but you can use pencil lead to conduct electricity.

Edited September 4, 2014 by rogeryermaw

[BurritoBandito]

Wouldn't conductivity help to homogenize charges across the surface though?

[Bobosan]

they use graphite to improve the appearance. after the powder is granulated, they roll it with graphite to coat and round off the sharp edges of the grains. the graphite actually slows the burn rate a little. graphite is also conductive and may make powder even more static sensitive...that part is speculation but you can use pencil lead to conduct electricity.

 

Graphite also helps to lubricate the grains so it easily flows into and through a micrometer powder measure.

[Maserface]

Ya I don't think mostly it has to do with lubricating the surface, so it pours and scoops more smoothly. For pyro, I don't see any reason to do it (except maybe fashion?)

 

Edit: also, aren't rough edges usually a good thing? Hence rough primes and the like. My gut tells me the rough, porous, structure of homemade powder grains might propagated fire quicker. Maybe I'm wrong

Edited September 4, 2014 by Maserface

[BurritoBandito]

Rough edges can be good in terms of ease of ignition, but are detrimental to consistency since a smooth edge is easier to replicate than an almost random jagged shape. Edited September 4, 2014 by BurritoBandito

[rogeryermaw]

burrito, that sounds like a valid area for testing. i'd be very interested in the results. generating a spark isn't that hard. just need some graphite.

 

bob, that is one of the reasons i remember reading when i did the bulk of my research on gun powder.

 

maser, that speculation is one of the reasons i granulate my b.p. by hand. i am only basing my opinion on what little i know of chemistry and physics, but the grains are less dense than pressed and corned pucks. i would think that the lower density would not only help to propagate the flame front more quickly, but also consume the individual grains more quickly resluting in higher chamber pressure and better lift with less powder. also something that could be tested.

[dagabu]

In short, it appears that graphite glazing, which could be done relatively quickly, was used a century and more ago to simulate the results of graphite-less polishing, which took much longer (five to eight hours). Highly-graphited powders were of inferior quality, suitable for trading with the natives in uncivilised countries, but yielded poorer performance with more fouling, and should be avoided by the knowledgeable.

 

Greener: The Gun and Its Development (tenth ed., 1910) (p. 550-1):

[Merlin]

Bottom line. Problem solved. It was the drastic change in humidity. The powder was wet. After dying it went boom once again. So from now on I will keep my lift and burst in ziplock bags and place a container of dryerite in the bag. before it was stored in plastic pails with snap on lids in a aft magazine and susceptible to moisture. The best kind of drierite (calcium sulfate I think) is the indicating type. It changes from blue to pink when it has absorbed moisture. Place it in over and use it over and over. The only thing I haven't quite figured out is why commercial goex is not as susceptible to moisture as home made. Since it is not much trouble I am also coating my bp with graphite. I dont know if graphite helps with locking out moisture but It is the only difference I can see between home made and commercial.