Stelmax 1961 Gap Filler & Sealant is easily applied PVC resin, pigment, plasticiser and solvent mixes, that will gap fill and bond readily to form maintenance free joints of exceptional strength when used to bond and fill rigid and plasticised PVC. Good adhesion can also be achieved when used with many porous substrates. 1961 is extensively used within the window industry for the installation of frames and attachments.