Polishing the powder grains by tumbling them in a wooden barrel improved their moisture-resisting properties, while the addition of a small amount of graphite made the process even more effective. Corned powder came into use in England in 1520.

Minor improvements to powder continued to be made chiefly by increasing the purity of its constituents and by experimenting with their proportions. In 1781 Richard Watson DD FRS, Bishop of Llandaff, who was also a professor of chemistry, ordained that for general purposes the proportions be saltpetre 75%, charcoal 15%, sulphur 10% - and for British gunpowder they have remained the same ever since. Later, in 1786, when asked by the Government for advice on improving the strength of powder he recommended the charcoal be made by 'distilling' the wood in closed vessels, and his recommendation was adopted.