Eco-House Orange Terpene is the most potent solvent Eco-House Inc. Solvent System. This solvent serves as a full fledged turpentine substitute for painters. Orange Terpene is a petroleum-free, highly distilled food-grade solvent. Just like all of Eco-House’s Fine Art Oils and Mediums Orange Terpene has a high archival quality that leaves no residue.