Sulphurless Black Powder is a common variant of Black Powder that contains no sulphur. This uncommon variety is used when it is desirable to prevent the contact between the sulphur and other chemicals, e.g. chlorates, for safety reasons.
To create it, simply mill charcoal and Potassium nitrate together. After this, mix with a solution of about 75% water and 25% isopropyl alcohol, with no less than 75% water. The alcohol helps the charcoal absorb the potassium nitrate solution by reducing water's surface tension, thereby allowing the solution to enter more of the charcoal's pores. The drying time of the composition is also reduced, as alcohol evaporates faster than water.
It is interesting to note that the binary mix has a burn rate peak is at approximately ~33% charcoal, whereas the maximum temperature is at ~23% charcoal. Therefore, to achieve the maximum burn rate, a ratio of 1:2 is preferred, where for maximum heat, 1:3 is the preference.
Using the 1:2 ratio, a respectable lift powder can be created after granulation. For best results granulate with water and without dextrin, though the resulting granules will be fairly delicate, the addition of dextrin will produce insufficient force to launch larger shells as its burn rate has been reduced. This lift powder composition should only be used if sulfur is unavailable, as the 74:14:10 formula produces larger amounts of expanding gas to lift shells.
An interesting study dealing with this subject can be found here: http://eprints.ru.ac.za/252/03/PUBLICATIONS/PEP14.pdf