Dust Explosion - Grain, flour, wheat

[Nereidalbel]

This is why I'm saying to use minor elementals to whip up a firestorm. You'll have leftover flour and burning bits of bags just waiting to burn, as well as any grass and flammable bits of hair, grass, and clothing. Throw in catapults launching bags of light, flammable things, and you get a firestorm. This will call for fright checks in the enemy ranks, produce plenty of smoke (any mages that can help with wind direction should blow that over the enemy), and overall be quite impressive to see.

[Zeta Blaze]

@Icelander;
If i were the PC and had aces to the city spice supply as well some of the spices would be very good additions to be mixed into the payload adding irritants to you explosion.
cumin, coriander, peppers especially dried and powdered. As for fresh peppers just the seeds and placenta chopped fine would probably be worth adding as well.

Other spices that could be of use would be Ground Black, White & Red Peppercorns are super effective and so widespread even in medieval times that i assume some is available almost anywhere.
Ginger, horseradish & ground mustered seed are also fairly notable and would make fine additions as irritants.
Poppy, garlic & onion could also be effective but they lose most of there unusual qualities when dried and powdered and in a moist form would not help with the explosion.

[Nereidalbel]

Originally Posted by Zeta Blaze

cumin, coriander, peppers especially dried and powdered. As for fresh peppers just the seeds and placenta chopped fine would probably be worth adding as well.

Cumin is actually going to result in a bigger boom per pound than flour, and not serve well as an irritant.

Honestly, the best way to look at it is "if it didn't start out as a rock, it can explode."

[kabson]

I didn't see paint on the list of powders, but if you want a real-world example of what a open-air dust 'explosion' can do there was paint explosion in a Taiwanese resort last year. It was more 'flame cloud' than explosion.

The BBC report provides some information. Careful, other reports quickly head into 'viewer discretion required' and several deaths eventually occurred.

[Icelander]

Originally Posted by Zeta Blaze

@Icelander;
If i were the PC and had aces to the city spice supply as well some of the spices would be very good additions to be mixed into the payload adding irritants to you explosion.
cumin, coriander, peppers especially dried and powdered. As for fresh peppers just the seeds and placenta chopped fine would probably be worth adding as well.

Other spices that could be of use would be Ground Black, White & Red Peppercorns are super effective and so widespread even in medieval times that i assume some is available almost anywhere.
Ginger, horseradish & ground mustered seed are also fairly notable and would make fine additions as irritants.
Poppy, garlic & onion could also be effective but they lose most of there unusual qualities when dried and powdered and in a moist form would not help with the explosion.

For a city of about 50,000 that serves as the granary for three field armies and a lot of peasant labourers around it, a total of ca 300,000 people, how much cumin, coriender, ground pepper, etc. do you think could be scrounged by a few people in less than a day?

I don't have any problems imagining hundreds of pounds of finely ground flour in bags around a mill, waiting for transport to bakeries and cooks in the governor's palace. But I imagine that most spice is stored in seed or corn form and only ground for the individual meal.

So you can't just pick up 50-lb bags of it finely ground. And it's not as if the PC and his men have the time or inclination to grind a ton of various spice seeds and corns to fine powder.

[Icelander]

Originally Posted by Nereidalbel

This is why I'm saying to use minor elementals to whip up a firestorm. You'll have leftover flour and burning bits of bags just waiting to burn, as well as any grass and flammable bits of hair, grass, and clothing. Throw in catapults launching bags of light, flammable things, and you get a firestorm. This will call for fright checks in the enemy ranks, produce plenty of smoke (any mages that can help with wind direction should blow that over the enemy), and overall be quite impressive to see.

Summoned creatures have to obey commands and have some kind of strange mental block that prevents them from reasoning too much about the consequences of attacking a superior force as part of their orders. On the other hand, they do feel pain and terror and are capable of panicking as easily as if they weren't summoned. In essence, rational fear before violence and danger actually strike is somehow blocked out by the control mechanisms that the summoning spell exerts over the simulacrums of summoned creatures, but primal emotions like terror and pain burn through it.

Air elementals and djinns are not immune to fire. They'll happily cavort through clouds of flour, spreading it around, even if that poses a risk to them in the form of enemy priest and mages eventually turning up and banishing, dispelling or killing them. But once that flour starts burning, they would take burning damage, even in whirlwind form, and probably panic even before the firestorm destroyed them.

[Zeta Blaze]

@Icelander
I agree most of the spice will be less ready to go but do the allied NPC millers in the city have any more productive thing they could do with there time compared to manufacture weapons by grinding mixed spices not flower in there mills? I also assume most of the spices will be in the same high end bakeries and store houses as the high end superfine white flower. I figure you can scrounge up a quarter ton all told of spices to powder while you find the high quality flower for little extra effort then have it ground and packed in time for the raid. This assumes that the city's millers have nothing more pressing to do ether as millers or as general labor I'm sure they would rather use there trade to help repel the invaders than just haul supplies and dig ditches.

@Nereidalbel
You have a point, but it has already been established that we dont expect a perfect boom, so any unburnt material acting as an irritant is the goal. The fact that it will combust better is just gravy. Plus I assume the burnt residue of all the dry spices I listed is a greater irritant than the residue of burnt flower.

[Bruno]

Originally Posted by Zeta Blaze

Plus I assume the burnt residue of all the dry spices I listed is a greater irritant than the residue of burnt flower.

I find that unlikely. They're going to be dehydrated if they're powdered instead of pastes. All you're going to get behind is soot (carbon powder) and half-burned spices. The volatile chemicals, which are the fun parts, are not surprisingly volatile and burn faster and better than the regular old plant-y bits. Even where not burned, they're going to be driven out by the heat (again, volatile) and then gone on the rising hot air, just like the smoke is. It's like burning pine shavings and expecting the pine tar to somehow escape unscathed.

I wouldn't personally stand right in the smoke of burning chile peppers, but that's because the average fire is going to be burning them at a low temperature and you won't finely powder them to improve the surface area. Improved surface area resulting in a FAE IIRC produces more complete combustion and higher heat than just tossing a bushel of them on a camp fire.

[Anthony]

Originally Posted by Bruno

The volatile chemicals, which are the fun parts, are not surprisingly volatile and burn faster and better than the regular old plant-y bits.

Not all interesting chemicals are particularly flammable; if the effects are by contact rather than by evaporation, it can be heat resistant enough. I don't have much knowledge about spices (which, for economic reasons, are probably a poor plan to start with), but urushiol (active ingredient in poison oak) is somewhat notorious for its ability to survive fires, making a poison oak bonfire is a good way to send people to the hospital.

[Zeta Blaze]

@ Bruno
the only spices i mentioned that would turn to pastes not powders are Poppy, garlic, onion, ginger, horseradish, and chilies.
Of these only Chilies, horseradish & poppy seeds saw any dehydration and powdering before the development of freeze-drying IIRC. I agree that much of the spices will burn up but we know that the explosions will be imperfect and will scatter the dust around so ether they burn and add explosive power or they dont and serve as irritants.

that means that some of the stores of Chilies and horseradish are likely to be dry and some fresh in the case of chilies this means that they are even spicyer as drying increases the potency of the capsaicin. I also know that drying chilies has been common practice wherever they have been cultivates.

Furthermore i know from experience that capsaicin is very heat resistant and supose that it is likely to remain in notable concentrations after the explosion assuming they were notable to begin with. It is true that most of the surfer compounds in garlic and onions will burn but they will transform in to more offensive smokes than most botanical material due to the relatively high surfer content. As for other spices i know Carvone, menthol, Limonene burn readily and should mostly burn chemically unremarkable based on what I have read.