Had a trip out on a Thames sailing barge (Cabby) last weekend. Was impressed by the appearance and feel of the sails, which were ochre/red.

Our dutch barge has very stained white sails, it would seem to make sense to 'dress' them to ochre; both to cover up the stains and to preserve them.

Is it possible to 'dress' modern synthetic sailcloth, or can you only do it with cotton sails?