Process for the production of a mercapto-terminated liquid polymer with the formula HS—R—(Sy —R)t —SH, wherein each R is independently selected from branched alkanediyl or branched arenediyi groups and groups with the structure —(CH2)p—O—(CH2)q—O—(CH2)r- and wherein 0-20% of the number of R-groups in the polymer are branched alkanediyl or branched arenediyl groups and 80-100% of the number of R-groups in the polymer have the structure —(CH2)p—O—(CH2)r—, wherein t has a value in the range 1-60, y is an average value in the range 1.0-1.5, q is an integer the range 1 to 8, and p and r are integers the range 1-10.The resulting polymer has an improved ability of recovering its original shape after release from deforming compression forces and improved tendency to recover during the application of those forces.