blocking powder
A finely ground resin used in dusting over the
impressions in silk and velvet before gold
tooling. Such resins are used in lieu of GLAIR because
moisture would stain the silk or velvet. The
powder has the advantage of requiring only a
moderately hot tool, whereas glair requires
considerably more heat to make the gold adhere.
Blocking powder, however, does not provide the
solidity of adhesion to gold leaf that is
obtainable with a liquid size; therefore, it is
generally used only when a liquid size is
impractical. (154 )