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-
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.
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.
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