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The Basics of Plastering
at Poplar Forest
| As with all restoration at
Poplar Forest, traditional methods and ingredients are being used in
plastering the ceilings and walls in Jefferson's home. The restoration team even
sought guidance on traditional plastering from the Scottish Lime Centre
Trust, an organization that promotes the appropriate repair of
traditional buildings. |
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Before masons apply plaster, carpenters
install flat pieces of wood called grounds around the perimeter of the
space. The grounds act as stops for the
plaster, which is applied to a thickness level to the grounds. At left
you can see the team installing grounds in Jefferson's bedroom. |
When plastering open areas, such as the
ceiling, the restoration team next nailed
hand-split strips of wood known as laths across the ceiling. The laths are
gapped, allowing the plaster to anchor itself to the wood. Photo at right
shows a craftsman installing lath in Jefferson's bedroom. Lath isn't
used when plastering over brick walls.
| Click on these pictures to see larger versions
of these close-ups.
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A wooden lath installation.
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The
reverse side of the lath after the first coat of plaster has been
applied. Note how the plaster curls around the lath
boards.
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| The plaster is composed
of traditional materials similar to the lime mortar used for the
bricks and the column stucco. Jefferson added baked clay dust, an
ingredient used in ancient Rome. As in Jefferson's day, horse hair is
added to make the plaster hold together. During preparation, a mason
holds a trowelful of plaster to the light to see if there are enough
hairs in the mix, about one every quarter inch. |
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Click on these pictures to see larger versions.
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A bundle of hair
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A "hairy"
trowel!
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The first coat of
plaster is applied to the lath or brick. This coat is known as the scratch coat
because it is scored in two directions with a three-pronged wooden
scratcher to help the second coat bond to the first. Scottish master
plasterer Alex Hylands is seen at right scratching the plaster.
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The second coat, called, known as the
straightening or brown coat, is applied several weeks later after the
first layer of plaster has time to cure. The second coat is as thick as
the first. |
| The final layer is the white coat, a
very thin layer composed mainly of lime and very little sand. Craftsmen
moisten the plaster with a damp brush as they lay down this final coat
to ensure that it is smooth. |
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