Pitch Varnish,,,You will want to use hard, dry pitch because it dries hard. The oozie stuff takes longer to dry and sometimes stays sticky a long time. What I do is put the chunks of pitch in a container and cover it with denatured alcohol. When the pitch disolves I strain it through a thin cloth to remove the solids, bark and wood pieces and dirt then pour it into an air tight jar. It will keep at least a year in the air tight jar.
When ready to use it I use a small artist type paint brush, dip it in the varnish and coat the wrap. When the alcohol evaporates the varnish is hard. You can clean the brush with alcohol but usually I let it dry and just soak it in the varnish while I do the wraps and it will be soft when I'm ready for it.
I use this varnish to seal any sinew wraps on arrows, for fletching, self nocks and when hafting stone points with pitch glue. I also use it on the shafts of hardwood shoot arrows. Usually I don't seal the shaft until after the fletching, self nocks and points are wrapped and do one end of the arrow, let it dry then do the other end.