Bonding polyamides. Their surface is plentifully moistened with concentrated formic or acetic acid and after a few minutes it is strongly pressed. The pressure should be kept for several hours. You can also make an adhesive for polyamides by dissolving thin pieces of polyamide in the above-mentioned acids or in 15% hydrochloric acid. Cover the glued surfaces with a thin layer of glue, press down firmly and leave for a few hours.