Granulating black powder

[Troy.Musillami]

I'm pretty new to making fireworks, so I'm at a loss and could use some advice. Google hasn't been much help or I'm not googling the right thing.

I've been having issues granulating. I don't know if I'm doing something wrong, or if I'm missing a step in the process. I mill for 4 hours minimum (it usually ends up being 4-1/2). The black powder coming out looks like airfloat charcoal, so I don't think my issue has to do with mill time, though I could be wrong. All my chemicals are from skylighter and I've been following the instructions on their website.

I do have well water and we use a water softener. I don't know if that could be an issue, but I had a lightbulb moment writing this and I'll have to pick up some distilled water next time I'm out to try as well.

Anyways, I've made several batches of black powder. When I granulate I only use enough liquid to pack my powder into a shiny ball. If I squeeze it, excess liquid doesn't seep out, but its also not dry if that makes sense.

My very first batch I didn't use dextrin. I mixed 75/15/10 and then used 70% isopropyl alcohol and granulated it. It worked great in terms of performance, but there was no binder so I had to be very delicate with it.

In recent batches I've used the same 75/15/10 recipe with variations of 1-3% dextrin by weight. I've tried using cold, warm and hot water, but my granules don't hold their shape. The moment I touch them they turn to powder.

I've also tried the same 75/15/10 recipe with variations of 1-3% redgum diluted in denatured alcohol and my results have been the same.

Hopefully I've including everything relevant without rambling too much. Thanks in advance.

[chris v]

Ok if I have this right your first batch was great but every other batch in other words a dud? Here's a checklist, 1st did you increase the size of the following batches 2nd did you test the batches prior to granulation, 3rd when you did the dex batch did you add it before or after milling, for dex in BP you add while milling 4th was the granules completely dry denatured alcohol is hydroscopic and will pull moisture from the air same as acetone. My advice start from the beginning it sounds like you did a 100g batch it worked and may have increased the batch size, try going to the smaller batch and go up from there when you notice a change in burn rate try increasing milling time but in some cases even if you increase milling time and there is little to no change go with the smaller batch. Stay away from well water unless it's tested for contamination and no softened water it has salt dissolved in it. The BP you can purchase doesn't use binders they use the press and corning method, skylighter has good instructions on this method

Goodluck