by Athena and Bill Steen - Cohabitat

The second layer
Optimally; the second earthen floor layer should be applied
while the first layer is still damp, yet leather-hard. If the first layer
dries out before applying the second layer, be sure to dampen it well
before starting, and while working. If for any reason, the first layer
showed any cracking, adjust the soil mixture and retest before applying
the second layer
The second layer of the earthen floor is applied in exactly the
same manner as the first. Once the floor has hardened, but is still
damp, it can be troweled, using a little water, to give a smooth, fine
polish. A spray bottle works well to apply the water. Wiping the floor
lightly with a wet sponge and troweling it will bring out the flecks of
straw.
Depending on the weather, the entire floor could dry in as short
of time as a few days in drier climates or as much as several weeks in
damper conditions. A fan could help speed up the drying process.
AD traffic should be kept off the floor during this time.
Method2
This method produces a floor that is not as durable as
Method /, but is easier to install.
The technique
It is possible to construct an earthen floor by tamping
or ramming. It can also be done in multiple layers, but at greater
thickness because it is done with a dry or slightly moistened
mixture rather than one which is wet enough to trowel. The
Initial layers of this floor need not be as finely screened as for
Method 1. Soil passed through a 1/2 inch screen is more than
satisfactory. Select a clay/sand mix as described earlier in the
text. Prepared road base has also been used with good results.
Each layer can be somewhere between 1.5 to 2 inches
in depth with the total depth of the floor at 4 to 6 inches or
more if conditions require it.
Adding water
The first layer can be applied dry and then moistened
slightly with a mister on a hose or a watering can. The soil
mixture should be wet enough that the clay can bind the
ingredients together, but not so wet that it can't be walked
upon without disturbing it. The mixture can also be lightly
moistened before applying. Doing so helps ensure that the
moisture is evenly distributed throughout the mix, but it is
more laborious.
Another option, which will help further stabilize the
soil, is to add boiled linseed oil to the water at a rate of 4
liters of boiled linseed oil, diluted with 2 liters of water for every
100 liters of soil (by volume).
Tamping
The mixture can then be roughly
leveled and then compacted with a plate
compactor. Hand tamping is clearly the
least expensive, but more laborious.
Simple tampers can be made from
plywood with a handle or metal plates
welded to a piece of pipe. Mechanical
plate compactors are commonly
available through tool rental outlets.
When using one, it is necessary to handtamp
the edges of the room where the
floor meets the walls.