When my black powder burns, it leaves a little red byproduct (little circles of hard red stuff on the surface ?

My powder consists of (roughly) 75% KNO3, 15% charcoal and 10% sulfur. What's making the red deposits?When my black powder burns, it leaves a little red byproduct (little circles of hard red stuff on the surface ?
That's hard to say without seeing it or having more info from you.





Possible sources:





1) It's coming from the surface that the powder is sitting on when ignited: melted/burned paint, oxidized surface products, etc.





2) There is a contaminant in your gun powder: maybe iron oxide, or some gunpowders have a type of powdered plastic or resin added to help identify where the gunpowder came from.





Hope this helps