Slack Wax is a translucent crystalline material in a solid state and a yellow, clear liquid when molten. It is derived from petroleum and is primary consists of a mixture of straight chain normal paraffin and branched, iso-paraffin hydrocarbons.

It is used in glass wool and textile treating, wax emulsions, paraffin wax production and candle production.

It contains low level of oil and it has a high congealing point.