substanceProof RedColors & materialsA named craft material / finish lemma (Proof Red) drawn as an exact public-domain workshop phrase.Proof Red is historically related to Marble.earth-colours seats orphan proof-red beside marble as a first craft peer — object speech, not a text-container or tradition dump.from Josef Bersch · The Manufacture of Earth Colours, PD Gutenberg #71219historically related to · sourced · documentedsourcesThe Manufacture of Earth Colours · Josef BerschBersch, The Manufacture of Earth Colours (PD Gutenberg ed.).