Arc External Grade Decorators Filler is a one part emulsion material which sets upon exposure to the atmosphere and forms a durable flexible seal. Arc External Grade Decorators Filler may be used internally or externally and contains a fungicide to discourage mould growth. Sealing gaps around window and door frames. Sealing/Filling gaps in skirting boards and coving. Sealing/Filling gaps in plasterboard. Arc External Grade Decorators Filler can be easily painted or papered over making it an ideal all purpose sealant/filler when decorating. General Sealing/Filling of internal and external fixtures.