- Q.How can pine resins be
sealed to stop bleed-through on exterior
siding?
A.Shellac has always
been considered the sealer of choice for pine
resins, but it is not considered appropriate for
exterior use. However, if the shellac is thinned
substantially, about one part shellac to four parts
alcohol, it may work. The primary problem with
exterior use of shellac is its brittleness, which
should be reduced by thinning.