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Screen mixed bp for spolletes


SignalKanboom

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I was wondering if I could use screen mixed bp for my spolletes? Would make it much easier to just screen mix and only use for that purpose.
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You can but each batch might likely have different burn characteristics that you'd need to test. You'll just never get the intimate uniform incorporation with screen mixing only vs granulating. And screened powders don't burn with the precision of wet-granulated powder. Or as fast and reliably. What's the problem with wet-granulating a large batch? It's easier to handle than screened powder/mill dust that floats everywhere, unless you're planning to wet it some before loading. Screen mixing is fast, sure. So is granulating--takes about 15 minutes to wet, knead, granulate x 2 through same screen, and however long afterwards to dry. Faster burning and comps more uniformly incorporated, meaning a more predictable burn.

 

And if it works predictably, you could make many at the same time and store the unused spolettes, to assure uniformity in construction, measuring, and burn time. Loose screen-mixed dry comp also has the tendency to separate components with handling--heavier individual components (uh, nitrate, then sulfur) settle towards the bottom via gravity, further decreasing BP uniformity. Not a concern with simply water or alcohol-granulated BP.

 

Or you could just buy some 1/4" time fuse made just for the purpose--a 10-foot roll will last you for many 100 shells. No tubes, no powder concerns, no ramming/pressing, uniform burn rate and stores well. Some folks even use visco for time fuse, but that to me seems slightly risky.

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one of my favorite cylinder shell builders uses goex ffffg to ram spollettes. it's the only thing he uses commercial powder for but likes it for this purpose because a little goes a long way and it is consistent from batch to batch so you only have to dial it in once. for this builder, consistency is of highest importance as salute effects can be fiddly to time just right.

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The biggest issue you're likely to face using screen mixed powder for spolettes is the burn rate. Meal D (the standard for spolettes) or commerical 4FG (more readily available and comparable to meal D) burns around 2.6s/in. Screen mixed power will likely burn much slower, which would require shorter powder grains in the spolette to achieve normal timings. Spolette timings are typically referenced by length of powder grain, either an actual measurement (one inch) or by number where the number corresponds to how many 1/4" increments are in the spolette (so a 1" powder grain is a #4 spolette). Longer timings are not an issue for slow powder, but shorter timings can create issues because if the powder grain is too short it's prone to blowing out rather than burning through. To some extent you can mitigate this by "drilling back" so ram 1/2" of powder and then drill it back to a 1/4" with a 1/8" drill bit. This also allows for very precise timing when using spolettes.

 

Time fuse works ok for cylinder shells, but you typically still need to glue the fuse into a tube essentially making a spolette with a time fuse core. Cross matched time fuse does not have nearly the surface area for taking fire that a spolette does, nor does it throw as much fire. Also, the tube gives you the length and strength needed for tying on spiking and pasting. The time savings are minimal and you still run into the same problem with short timings. It's far easier to ram a 1/2" of powder into a 3" tube than it is to glue a 1/2" piece of fuse. Time fuse is fine for small single break shells, but for larger or more complicated shells a spolette is the way to go. Plus you never have to worry about the supply suddenly drying up if, say, a virus suddenly appears. 10ft of fuse will disappear real fast when you're building shells with lots of inserts in them. I just shot a 6" 4 break that had around 4ft of fuse in it (spolettes for all the main breaks).

 

I used homemade milled powder for my spolettes for a year or so and it worked fine. I milled a dedicated batch without any binder and granulated it through a fine screen. I now use 4FG just for the sake of ease and consistency. It's stupidly expensive compared to the cost of homemade, but a lb of powder will last for years.

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Milling remotely has become a problem. I cannot run my mill anymore because of location. I made a 10 ounce batch and made some BM. I will have slurry that I will re-wet and granulate and use for priming, or spolettes if granulated bp can be used for spolletes. For lift in the future I will have to resort to 2fg like whichita buggy whip talks about. Any advice on how to proceed without killing would be appreciated. Once Im living back on some acreage this wont be an issue.
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If your BM slurry has dextrin in it to stick to your string, it will make hard BP granules that are very difficult to get back to dust without milling. With dextrin, BP can be rewetted to make more BM or putty for granulating to lift/burst (if fast enough) and for spot-priming fuses and such. Need powder to reuse for priming stars or for purposes that require reliable compaction/ramming.

 

Some have had improved successes with screen-mixed BP after individually supermilling components to dust, which can be done anywhere safely, including indoors (clean out mill jar between chems). I'd still wet-granulate supermilled/screen-mixerd it just the same, to both better incorporate the chems and make it faster, and to make soft granules (if no binder) of any size desired that can be reduced back to dust if also desired.

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It is fast enough. When lit on top of paper it doesnt burn the paper, but it does leave a black dust burst type effect. I believe that it just happened he smoke, or residual charcoal/lead from milling. I guess I will just have to mill s/c together and the kno3 separate, then screen them together. Didnt someone mention a guy with a tutorial that made fast bp with just screens? I looked, but could y find it.
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Thank you! I dont like spending that much on bp, but until I have a place to mill its nice to know I have a store bought option for lift and spolletes. Im learning a lot from all of you.

 

To shark, I like sticking with the traditional construction of shells, something about the construction using spolletes I really enjoy and find fascinating.

 

Btw I know I am either missing or have too many ls or ts in spollete. (Spollete, spolettes, spollettes)

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Btw I know I am either missing or have too many ls or ts in spollete. (Spollete, spolettes, spollettes)

It's correctly spelled "spolette" but you'll see it spelled all three ways by those who aren't certain or just don't care--we'll know what you're talking about,although accurate spelling is appreciated. And absolutely essential with chems (formulas, too), to prevent mix-ups and possible accidents..

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