Flash powder with MnO2, Al and red P
It is fairly well known that a mix of manganese dioxide and aluminium can be used as a thermite-like mix, which burns very fast and brilliantly, even more so than the well-known mix of Fe2O3 and Al. However, these thermite mixes are not easily ignited and also quite large amounts (in the order of magnitude of grams at least, preferably tens of grams) are needed in order to get them going. Even with the flame of a propane torch, a general thermite mix is not easily ignited. The mix of manganese dioxide and aluminium is not an exception to this.
The effect of adding a small amount of red phosphorus to the mix, however, is dramatic. Adding only 5% of red phosphorus makes igniting the mix very easy (just keeping it a few cm above a flame ignites the mix immediately) and it also burns incredibly fast, almost with explosive violence. It also is remarkable that no large amount is needed, a batch of just a few tens of mg is sufficient to get a violent reaction. Normally the larger amounts are needed, because small amounts suffer from too much heat loss.
Prepare a mix of 50 mg of MnO2 (fine powder) and 20 mg of aluminium (german dark). Roughly speaking, this is approximately 2 volumes of MnO2 powder and 1 volume of powder of Al. This mix gives very bright flashes, but requires quite some heat to be ignited.
Mix in a tiny amount of red P, such that around 5% of the mix is made up of red P. This makes the mix much easier to ignite and the flashes remain incredibly bright.
I put a very small amount of this mix on a coin, just showing how small an amount is used. This most likely is just a few mg of mix:
The coin has a diameter of 2 cm, so one can easily see that the speck of mix is very small. When this little amount of mix is ignited, then the result is as follows: flash1.avi
When a somewhat larger amount is ignited: flash2.avi
Throwing some of the powder into a flame: flash3.avi
Some nice frames were extracted from the AVI movies:
Just 30 milliseconds after the brightest moment of explosion (still very bright and overexposed):
From another AVI, appr. 100 ms after the explosion, nice bright sparks are still flying around through the air:
