12 Cartridges of Polycell’s Decorators Caulk. Polycell Polyfilla Decorators Caulk is a flexible permanent acrylic sealant specially formulated for internal and external use in areas subject to movement. It is suitable for sealing around architraves and cornices, sealing cracks between skirting boards and walls, pointing around window and doorframes and filling cracked plaster. It gives a smooth finish that does not require sanding.