Tar can be more or less sustainable depending on its source, production method, transport, use, and disposal. Wood tar from responsibly managed forests is very different from coal-tar or petroleum-related products.
Sustainability is not a property of the word tar. It depends on the full material story. A wood tar made from managed forestry residues may begin with a renewable feedstock. A coal-tar product comes from fossil coal processing. A roofing or road product may be tied to petroleum, industrial chemistry, and difficult disposal.
Even wood tar is not automatically sustainable. Production involves heat, smoke, labour, emissions, and raw material use. If trees are overharvested or inefficient processes waste fuel, the environmental case weakens. If tar extends the life of timber, rope, fencing, or a building, the case can improve because fewer materials need replacing.
Traditional Stockholm tar is often attractive to people interested in natural and heritage materials, but the label alone does not prove modern sustainability. Source transparency, responsible forestry, careful use, and avoiding unnecessary application all matter.
The best answer is conditional. Some wood tars can fit a low-waste repair culture. Some tar-related materials belong to high-impact industrial systems. Tar should be judged by source, purpose, lifespan, and end-of-life handling.