ATTENTION TREASURE HUNTERS
Television Producers are searching for Treasure Hunters that are ready to find
Dry Washing is the use of a
"Dry Washer" to separate gold from sand and gravels without the use of
A dry washer begins with a
"Grizzly" onto which gravels are shoveled. The grizzly is usually a
piece of expanded metal mounted on an aluminum or wood tray. The grizzly is
mounted at a fairly steep angle and above the dry washer's sluice box. Anything
larger than the holes in the grizzly falls or is scraped away and falls behind
the dry washer. Anything smaller than the holes in the grizzly falls onto the
tray and into the top of the sluice box.
The dry washer's sluice box is
designed similarly to that of a conventional sluice box that uses water with a
few exceptions. The riffles in the dry washer's sluice box are pointed up towards
the top of the box, instead of towards the bottom of the box. This allows gold
to be trapped under the riffle. Holes drilled into the bottom plate of the sluice box allow forced
air to blow away anything that is lighter than gold (and black sand). Therefore,
the gold and black sand remains in the box, trapped behind the riffles, and
anything lighter is blown away.
The air is forced through the holes
in the sluice box by one of two methods. The original way used by the
old-timers, and still used today, is a bellows mounted underneath the sluice
box. The bellows is powered by a hand crank mounted on the side of the dry
washer, or a gas or electric motor using pulleys and belts. This is called a
"puffer type dry washer."
The second way, which is more
popular, is by means of a leaf blower (gas powered). The leaf blower blows air
through a flexible hose similar to home dryer hose, which is connected to the
bottom of the sluice box. Inside the sluice box, a fan is mounted that spins as
air is blown into the box. Mounted on the fan is a weight that throws the fan
off balance when spinning, and vibrates the entire box. This additional
vibration assists in forcing flour gold to the bottom to be trapped. The air is
blown up through holes drilled in the bottom plate of the sluice box. The holes
are located directly behind the riffles. The plate is covered with a fine mesh
material that keeps "fines" from leaking through. The
"heavies" are trapped behind the riffle and the lighter material is
The grizzly and sluice box are mounted on a
frame in such a way as to have the grizzly "feed" the top end of the
sluice box. The sluice box is mounted on the frame at an angle, with the top of
the sluice box mounted solidly to the frame, and the bottom end suspended by a small chain and
springs to allow efficient vibration.
And there you have it.
Dry washing requires that the sand
and gravels being dry washed are powder dry. If necessary, shovel the material
onto a tarp to dry in the sun, then poured into the grizzly.
Dry washing is very efficient, but
not quite as efficient as dredging. But, when water is scarce or non-existent,
dry washing is the method of choice.
for books and equipment for Dry Washing in the Mercantile
a tip or technique