Formation occurs in stages:

Stage 1 — Novolac: Phenol + HCHO (excess phenol, acid catalyst) → linear polymer. Ortho and para positions of phenol react with HCHO via electrophilic substitution → methylene bridges (-CH2-) between phenol rings. Novolac is thermoplastic at this stage.

Stage 2 — Resole: Phenol + HCHO (excess HCHO, base catalyst) → partially cross-linked prepolymer with -CH2OH groups.

Stage 3 — Bakelite: Novolac or resole heated with more HCHO and cross-linking agent (hexamethylenetetramine) at high temperature → extensive 3D network. All three positions (2 ortho + 1 para) of each phenol ring participate → THERMOSETTING.

Properties: Hard, rigid, excellent electrical insulator, heat-resistant, chemically inert. Once set, CANNOT be remolded (cross-links are covalent — breaking them means destroying the polymer).

Uses: Electrical switches, plugs, sockets, pot handles, billiard balls (historically). Being replaced by modern plastics but still used for electrical insulation.