Plastic sheeting may be clear or coloured.
Care must be taken that the colour is appropriate
for the ambient conditions. For example, white or
lightly coloured sheets reflect the rays of the sun
and, hence, help to keep concrete relatively cool
during hot weather. Black plastic, on the other hand,
absorbs heat to a marked extent and may cause
unacceptably high concrete temperatures. Its use
should be avoided in hot weather, although in cold
weather its use may be beneficial in accelerating
the rate at which the concrete gains strength.