80/20 Amatol.

  Amatol was developed by the British in World War I as a way of conserving
their meager TNT supplies. It is composed of AN and TNT in varying ratios,
the most common being 80/20. It is slightly more effecient than TNT when
used in breaching charges, but since it contains AN it is somewhat hygro-
scopic and must be well sealed against moisture. It has a detonation vel-
ocity of 16,000 feet per second, almost twice that of straight AN. It is
very insensitive, and while this makes it safe to handle (in fact, the
blocks can be cut up with a hand saw), it can also make it harder to det-
onate.
  To be on the safe side, a booster should be added. One way to accomplish
this is to bore a booster well into the cast block using a 3/4-inch wood
drill bit. Dissolve some of the leftover TNT in hot acetone, pour the res-
ulting solution into a container of cold water, and stir vigorously. The TNT
will precipitate out of the liquid in its crystalline form, which is the
most sensitive type. These crystals are pressed into the booster cavity
using heavy hand pressure, leaving a hole in which to insert the detonator.
A standard No.8 blasting cap will initiate the TNT, which in turn will det-
onate the amatol. If properly packaged, amatol can be stored for long per-
iods of time with no change in sensitivity, power, or stability.
  As an interesting aside, amatol was used early in World War II, but a
Canadian TNT plant changed things. Though the company had never manufactured
TNT before, production was unusually high. When the inspectors went to find
out why, they found the normal manufacturing process had been reversed.
Since this "mistake" increased output to more than three times that of any
other comparably sized plant, all other TNT manufacturers adopted it. So
much TNT was produced that there was no longer any need for amatol, and it
was phased out.
Amatol production is an excellent way of stretching an explosives supply,
getting more bang for your buck, as it were. It is not as safe to make as
some other high explosives since it uses molten TNT (very shock-sensitive),
but it should present no trouble if reasonable care is exercised.

Procedure:
  1) Heat a kettle containing eight parts finely powdered ammonium nitrate
     to 90øC on a water bath. A flour grinder at low speed is adequate for 
     powdering the AN. Seal the receiving container immediately after grin-
     ding the AN, as it will absorb moisture from the air.
  2) Heat a second kettle containing two parts TNT on a water bath until
     the TNT is melted.
  3) Pour the TNT into the first kettle containing the AN and stir until
     completely mixed. The amatol will resemble wet brown sugar and have
     a consistent color and texture when properly mixed.
  4) Pour the amatol into block molds or charge containers while it is
     still hot. Use a cover to gently press the surface for maximum density
     and to remove air bubbles. It is important that the blocks are protec-
     ted from dampness or other moisture. Sealing them in plasticbags is a
     good method, as is wrapping them in wax paper and dipping them in wax.
     Be sure to form a cap well before they are sealed.

