Barrettine Patent Knotting is great for sealing resinous areas on wood before painting.
The formula includes a fast drying shellac in alcohol which stops natural resins found in wood from seeping through to the surface, ruining the finish and it prevents the resins being disolved by the solvents found in most paints.
Patent Knotting provides a mid-brown finish and can be used internally and externally.
Where waterbased and lighter coloured modern paints are to be used, use White Knotting instead.