POPULARWOODWORKING.COM ■ 27coats. The directions on the bag
of concrete mix give you a good
starting point, but you may want to
experiment a little if this is your fi rst
time using the material.
Packing the form is pretty straight-
forward. Pour a handful of the mix
into the form, and use your hands
to pack it in place. This fi rst coat is
going to be just under a^1 / 2 " thick,
so keep that in mind as you move
through the form. Once you have the
fi rst layer in, wait for the concrete to
cure. Depending on the conditions
in your shop, this could take an hour
or more. You’re not looking for a full
cure, but just enough so the fi rst con-
crete layer can support the second
layer as you pack up the vertical leg
surface. If it’s not cured enough, it’ll
slump off the form, and it’s not fun
(see sidebar on page 28).
Before you pack the second layer,
make sure to place the sheet of AR
mesh in the form. Then pack as
you did the fi rst layer until you’ve
reached that 1" thickness. You may
be tempted to try and smooth or
screed the fi nal layer after it’s all
packed, but the glass fi bers in the
concrete make that diffi cult. The
glass fi bers tend to catch on the
screeding board, which makes it dif-
fi cult to achieve a level surface, and
can sometimes pull the face coat
away from the edges of the form. It’s
best to just leave it as is and smooth
after it’s cured.
14 The form is packed in multiple
steps. It’s not an exact science–the
way the material behaves depends
not only on the amount of water in
the mix, but also the conditions in
your shop.
15 Getting the hang of packing the
form happens pretty quickly. After
the fi rst layer is packed, you wait a
bit for the concrete to set up so you
can pack the second layer.
16 You might be tempted to try and
smooth out the concrete once the
form is packed, but it’s much easier
to grind this fl at after it’s cured.14
15
16