Calculating the bp equivalent from a composition

[Almostparadise]

Maybe someone wouldn't mind explaining the steps? Please?

[Crazy Swede]

I recently was directed to this article when discussing the subject:
https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2020-10/Black powder equivalency.pdf

I have not read it yet though but I hope there is interesting information there!

Regarding your question, for what purpose do you want to do a theoretical comparison of black powder to other pyrotechnic mixtures? Without doing actual tests, it will be very hard since a lot of things, like pressure dependency and flame spread, are difficult to predict in theory.

[Almostparadise]

I just want to be able to try out black powder equivalents in different glitter compositions. The also I feel like it would be a good way to use up some of my leftovers.

Edited October 22 by Almostparadise

[Crazy Swede]

I'm not sure I follow?

Do you mean calculating oxygen balance or maybe potassium/sulphur ratio for potassium sulphide formation?

[Carbon796]

Converting the individual components of a scratch mixed glitter comp. To a BP based glitter comp. Like a traditional tremelon using 7FA as the base.

Edited October 23 by Carbon796

[Crazy Swede]

I’m not sure how I would do that and I’m not sure if it is possible since glitter compositions based on commercial black powder behaves differently compared to “scratch mixed” glitters. 

I still do not get your need?

Do you want to use commercial black powder for glitter or do you want to improve an existing scratch mixed glitter composition?

Have you read Winokurs monograph about glitter in Pyrotechnica No. II?

[FrankRizzo]

You'll typically adjust the amount of bp base, based on the most acceptable ratio of the charcoal, sulfur, and potassium nitrate in the formula. You can always add more of the individual ingredients afterwards.

For instance:

Tom’s modified Win 20 glitter

(https://www.fireworkscookbook.com/firework-recipe/gold-strobe-toms-modified-win-20-glitter/)

47 potassium nitrate

9.8 charcoal

16.7 sulfur

11.8 MgAl

6.9 sodium bicarbonate

3.9 red iron oxide

3.9 dextrin

 

We know that 100g of 75-15-10 BP base will have 75g of potassium nitrate. We need, at max, 47g of nitrate to fill the needs of the formula. So, 100g is too much. We need to find what amountof BP will get us that 47g. In this case, we need [(47/75)*100] = 62.7g.

That 62.7g of BP will give us:

(62.7g x 0.75)=47g potassium nitrate

(62.7g x 0.15)=9.4g charcoal

(62.7gx0.10)=6.3g sulfur

 

Tom’s modified Win 20 glitter becomes:

62.7g BP Base
(9.8-9.4)=0.4g charcoal
(16.7-6.3)=10.4g sulfur
11.8g MgAl
6.9g sodium bicarbonate
3.9g red iron oxide
3.9g dextrin

You'll find that sometimes solving for potassium nitrate gives too much sulfur or charcoal for what the formula needs. In those cases, you might need to instead solve for the component that is causing the overage and add nitrate.

 

[Crazy Swede]

Ah, now I understand the question!

Still, glitters are very sensitive and the formula will not look the same if you look at the sum of each ingredient when comparing formulations based on black powder and scratch mix respectively. 

[Almostparadise]

7 hours ago, Crazy Swede said:

Ah, now I understand the question!

Still, glitters are very sensitive and the formula will not look the same if you look at the sum of each ingredient when comparing formulations based on black powder and scratch mix respectively. 

I had read about different mixing techniques in Glitter Chemistry and Techniques, Lloyd Scott Oglesby. Much of the books chemistry content is beyond my understanding therefore slow to absorb. The different mixing techniques he lays out sounds exciting and something i would like to try out. Like marbling in the meal powder and using dampened granules etc. Also as a way to use up random left over material. I am pretty new at this so nothing too crazy 😉. I am still in awe what can be done with just the basic bp ingredients plus Al, Ti and FeTi! 

Edited October 23 by Almostparadise

[Almostparadise]

9 hours ago, FrankRizzo said:

You'll typically adjust the amount of bp base, based on the most acceptable ratio of the charcoal, sulfur, and potassium nitrate in the formula. You can always add more of the individual ingredients afterwards.

For instance:

Tom’s modified Win 20 glitter

(https://www.fireworkscookbook.com/firework-recipe/gold-strobe-toms-modified-win-20-glitter/)

47 potassium nitrate

9.8 charcoal

16.7 sulfur

11.8 MgAl

6.9 sodium bicarbonate

3.9 red iron oxide

3.9 dextrin

 

We know that 100g of 75-15-10 BP base will have 75g of potassium nitrate. We need, at max, 47g of nitrate to fill the needs of the formula. So, 100g is too much. We need to find what amountof BP will get us that 47g. In this case, we need [(47/75)*100] = 62.7g.

That 62.7g of BP will give us:

(62.7g x 0.75)=47g potassium nitrate

(62.7g x 0.15)=9.4g charcoal

(62.7gx0.10)=6.3g sulfur

 

Tom’s modified Win 20 glitter becomes:

62.7g BP Base
(9.8-9.4)=0.4g charcoal
(16.7-6.3)=10.4g sulfur
11.8g MgAl
6.9g sodium bicarbonate
3.9g red iron oxide
3.9g dextrin

You'll find that sometimes solving for potassium nitrate gives too much sulfur or charcoal for what the formula needs. In those cases, you might need to instead solve for the component that is causing the overage and add nitrate.

 

Great! I understand now. Thank you for spelling it out so clearly. I figured it would be handy to know and have in my notebook. 

[Almostparadise]

10 hours ago, Crazy Swede said:

Have you read Winokurs monograph about glitter in Pyrotechnica No. II?

No, but now that I know about it I definitely will read it. I think I know where to find it too. Maybe. 

[Carbon796]

18 hours ago, Crazy Swede said:

Ah, now I understand the question!

Still, glitters are very sensitive and the formula will not look the same if you look at the sum of each ingredient when comparing formulations based on black powder and scratch mix respectively. 

While the formula may not look the same. All that really matters, is that the builder prefers the change.

I used to use a modified version of w16 or w20. BP/Polverone base, additional bicarb, a specific Mg/Al mesh range. Wasn't really w16/20 anymore. But, it was tuned to my preference. Which as a builder, that's all that really mattered to me.

 

Edited October 24 by Carbon796

[Mumbles]

BP vs. component chemicals vs. a combination all give somewhat different results that's up to the builder to determine what works best for them. The example that comes to mind is Lancaster Yellow Glitters. They're all meal based as far as I remember. It's a nice composition that I prefer a little more as comets than stars. Long, sparkly tail that I just think is more effective as comets as opposed to stars. 

When making it as written with meal, it's still very nice, but has a bushier effect and a more regular flash rate to the glitters. My experience is that a lot of glitters made with a meal base follow this general trend.  It's a little cleaner effect.

When making it with meal components, the tail is longer and a little thinner and the flashes are a little more irregular. Part of that may be due to the fact that unmilled components are by nature probably going to be a little coarser. Coarse components in glitters can really draw out the flashes of the glitter effect. It can be used to great advantage, or overdone and drop a lot of fall out.  

Somewhere in between using a portion of meal and a portion of meal components is where I like them for comets. You can find that nice balance between long, beautiful tail, while keeping the effect cleaner and staying up in the air.  

Just adding additional parts meal or dark flake aluminum to glitters can clean them up if they're unusually slaggy or dropping a lot of fall out.  You can see this used in a handful of the winokur compositions.