Novolak

Novolaks (sometimes: novolacs) are low molecular weight polymers derived from phenols and formaldehyde.

The term comes from Swedish "lack" for lacquer and Latin "novo" for new, since these materials were envisioned to replace natural lacquers such as copal resin.

Typically novolaks are prepared by the condensation of phenol or a mixture of p- and m-cresol with formaldehyde (as formalin).

Oxalic acid is often used because it can be subsequently removed by thermal decomposition.

[1] Novolaks are especially important in microelectronics where they are used as photoresist materials.