Green’s Dictionary of Slang

(Aus.) a strong, coarse green tea, which stained the drinker’s lips.

1852		G.C. Mundy Our Antipodes I 329: Another notorious ration tea of the bush is called ‘Jack the Painter.’ This is a very green tea indeed, its viridity evidently produced by a discreet use of the copper drying-pans in its manufacture.
1878		Australian I 418: The billy wins, and ‘Jack the Painter’ tea / Steams on the hob.
1880		G. Walch Victoria in 1880 113: Special huts had to be provided for them [the sundowners], where they enjoyed eleemosynary rations of [...] ‘Jack the Painter.’.
1890		‘Rolf Boldrewood’ Colonial Reformer I 152: He drank his ‘Jack the Painter’ tea milkless.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.].
1908		E.R. Emerson Beverages, Past and Present 149: ‘Jack the painter’ [...] was a green tea of such a vivid colour that there could be no doubt as to its derivation.
1924		G.H. Lawson Dict. of Aus. Words And Terms 🌐 JACK THE PAINTER – Strong bush tea.
1945		Baker Aus. Lang. 83: Jack the painter [derived] from the stain left round the drinker’s mouth or in the billy (at least, that is the approved explanation).