Addition Filler to Resorcinol Resins

There are no filler that are specifically suitable for use with resorcinol resins, so the remarks made in last article broadly apply here.

To incorporation of limited amounts of filler is often desirable in helping to reduce shrinkage stresses, retain the glue in the joint, and improve gap-filling properties. Moreover, a satisfactory gluing viscosity, for example 40-100 poises at working temperatures, demands a relatively high resin content if no filler are added. Commercial resorcinol adhesive therefore frequently contains some filler, either in the resin or in the hardener. In some applications it may be permissible and indeed advantageous for the user to add a further quantity of filler, perhaps also with some solvent. The incorporation of a small amount of filler does not lower the adhesive strength, indeed it frequently increases it, and moreover, also reduces the scatter of strength values which is a common features in any set of glued joint, whatever the adhesive. The use of pulverized fuel ash as a filler is interesting and has recently been favorably reported. The addition of white or pale colored filler or pigment reduces the dark color of a resorcinol resin to only a limited extent.