The traditional answer was to apply Shellac Knotting and 'seal' in the resin. However, many years of research and on site experience have shown that this method is not completely effective, even with paints, with which it is traditionally used. Moisture vapour permeable (sometimes referred to as microporous) woodstains such as the Sikkens Cetol range, attempt to deal with the problem in a different manner by allowing resin to filter through the finish without blistering or peeling, hence full protection is maintained.
In the short term, resin exudation tends to look unsightly, but within a year or so the excess resin becomes exhausted and exudation ceases. The initial resin should be cleaned from the timber using a lint free cloth dampened with cellulose thinners or methylated spirits.