Cresol-Formaldehyde Resin for Wire Enamel, Jackson and Hall 1938

Cresol and formalin, with a little triethanolamine as catalyst, are boiled under reflux for about two hours until the resin starts to cloud out, dried under vacuum below 80 °C and thinned with cresol to a 50 % solution. GE's wire-enamel patent (Jackson and Hall, 1938) gives the recipe; heat later cures it hard. The picture: our diagram of the cook.