Gorga is the carved and painted ornament that runs across the gable and outer boards of a Toba Batak rumah bolon. The board is incised first, then blackened; chalk-white line-work is laid into the cut and red fills the lobes. Three pigments, all made on site: tano buro white earth, batu hula red stone, plants pounded with cauldron ash for black.

The triad is cosmology, not palette. White is the upper world, red the middle world of the living, black the lower. This system keeps that reading: black is the ground you build on, white is the line cut into it, red is what fills the space where people act.