Amount Wanted Print Recipe










Suitable Substitute


My polverone is ordinarily NOT milled. It is intended mainly to act as a combustible filler or an adjunct to commercial black powder or a flash bag, that’s OK. I very much agree that “the incorporation of the dissolved KNO3 into the body of the charcoal particles” is important, and my method of making polverone takes advantage of the much greater solubility of saltpetre in hot water than in cold. Here is what I do: Mix: 18 lbs. saltpetre 4 lbs. air float charcoal 3 lbs. sulphur 1 lb. 12 oz. dextrine Sieve the saltpetre, sulphur and dextrine separately through 40-mesh. Blend by hand and sieve through 20-mesh onto the coal which has previously been weighed out and placed in the receiver. When all is through, blend by hand and sieve 3x through 20-mesh. Now, set out two galvanized wash tubs and your granulating screen, which should be 3X3 hardware cloth. This is somewhat hard to locate compared to 2X2 or 4X4, but is worth the effort to find, because it produces a particle size range most comparable to 2F black powder. Set out a large scoop, such as bakers use to handle flour, and a wooden stick for stirring. Set out half-a-dozen 2X3 foot screen-bottom drying trays lined with 30# kraft. Place 6 lbs. of water in a covered kettle on a camp stove or hot plate, WELL AWAY from where you have your mixed composition. Put the composition into one of the wash tubs. When the water has come to a rolling boil, pour all but a little bit of it onto the composition and stir with a stick. The dissolution of saltpetre is profoundly endothermic and the damp composition will soon be cool enough to work with the hands. Blend the water in as thoroughly as you can with your hands. Make some of it into a “black snowball” about big enough to hold in both hands. Place the granulating screen over the second wash tub and rub this ball of composition over the screen, pressing it down firmly as you rub, causing the granules to fall into the wash tub. When done with the first ball, make another and continue till all of it has been granulated into the tub. Now place the granulating screen over the first, now empty, tub. Using the scoop, pick up and put some of the previously granulated composition onto the screen and shake/rub it through. Continue till it has all been granulated back into this tub. When complete, re-granulate a third time into the tub just emptied. The purpose of this repeated granulation is first, to distribute the water evenly through the mix, and secondly, to aerate and cool the mix. You will note each time you pass the granules through the screen, they become dryer on the surface and less prone to stick together. This is partially the consequence of drying, but also partially because as the temperature of the water falls, the saltpetre goes out of solution. Finally, granulate a fourth time onto the paper-lined trays. A batch this size will fill five or six trays with a thin layer of polverone. Don’t make it too deep, as this will interfere with drying. Let the trays stand in the sun and the breeze for half an hour to 40 min. You can check drying by lifting up a corner of the kraft liner in a tray, and see if the granules flow more-or-less freely or if they are prone to stick to the liner. When they flow more or less freely, it’s time to re-granulate one last time onto fresh, dry, liners. If this is done right the liners onto which the polverone was first granulated will hardly be soiled – just damp. They can be saved, dried out, and turned over to use another time. Let your polverone dry in a shady dry place, preferably inside a dehumidified and heated/air conditioned building, for 2-3 weeks. When dry, sort by granulation. I typically first pass mine through the 3X3 screen used to granulate it to break up any clumps. Using the method described, you should not have any hard clumps that are difficult to break up, as you will if you just dampen and granulate right away onto screens. The polverone is then shaken on an 8X8 screen. What is retained on this screen is bagged (I use the anti-static plastic bags in which commercial black powder originally came) and labelled “coarse.” This material will be approximately the same size range as 2FA and should make up the bulk of the polverone. The material passing 8X8 is shaken on window screen. What is retained on window screen is bagged and labelled “middle.” What passes window screen is bagged and labelled “fines.” The middle polverone is useful for smaller shells, filling around inserts, etc. Fines can be used for priming, or when enough are accumulated, can be dampened and re-granulated. As for “green powder” – at black powder mills, the “green charge” is what the mixture of saltpetre, charcoal, and sulphur is called before it is milled. It is thus “green” in the sense that it is raw, unfinished, immature or unripe – the reference is not to its color. This is not particularly a fireworks usage, and I have never heard any professional fireworks man speak of polverone or home-made meal as “green powder.” Polverone made with boiling water as above is faster than unmilled powder that has just been damped with cold or tepid tap water and granulated. By the way, I claim no originality for this method – it is how I was taught to make it, and how the person who taught me learnt how to make it himself. I have used my polverone to lift small (up to 3″) shells and mines and it certainly works – you just have to use more of it. It isn’t the equivalent of a ball milled powder. I imagine that if one were to use a better charcoal and ball mill the composition before granulating it could be made much stronger. Pressing is important to make powder of a density comparable to the commercial product, but I think this has less to do with speed and power than many people think. Powder density is an important issue especially with cartridge firearms, because the volume of powder that can be loaded in a cartridge has its limits and hence the denser the powder is, the greater the charge weight can be. This isn’t so important with fireworks, since we don’t have to make the lift charge of a shell fit in a fixed amount of space. In the nineteenth century, when the variety of black powders available was much greater, denser powders were favored for use in rifles while less dense ones were selected for shotguns – because they burnt faster! The old Ideal handbooks from this period caution against using black powders intended for shotgun use in rifle cartridges for this reason. It seems to me that pyrotechnists making their own black powder have not thought through the issue of powder density as well as they might. – Mike

Author: M. Swisher

Source: http://www.passfire.com/

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