weight ration of potassium nitrate to charcoal

[rider]

What's the weight ration of Potassium nitrate to charcoal? I don't have a small scale precise enough to measure out the weights I need, so I figure the next best thing is figuring out the weight ratio of the two main ingredients.

Help?

[asilentbob]

I'm not really sure what you are asking for...

Ratio of potassium nitrate to charcoal in a composition? If so look up sulfur-less black powder in a composition database.
Relative weight of 1 mol of potassium nitrate compared to 1 mole of charcoal? In which case you can find a periodic table and calculator on your own.
Volume to weight ratio? IE density. Varies.

If you have a cheap low accuracy scale, the easy thing to do is scale up batch size so that being a few grams off doesn't really matter. This is why postal scales are generally fine for pyro.

When you see a composition like 75 KNO3 : 15 charcoal : 10 sulfur... its in parts... since these add up to 100 its in percent too. You can use any weight measurement unit. IE milligrams, grams, pounds, kilograms, tons, etc... You can't use volume because the density of all the components isn't equal. So 75g:15g:10g. = 100g total BP.

Since I really don't understand what you are asking... I don't know... hope this helped.

[The Savage]

You can pick up cheap digi scales that are accurate to 1g for under $20. Not great, but better than nothing.