Hull Blacking Types.
Hull blackings fall into two distinctly different types: Bitumen based and Coal Tar based. These coatings when aged have very similar appearances - but it is very important that you know what you have on the hull before purchasing and applying a new coating.Bituminous products are spirit based and can be applied over any existing coating type without issues - by owners and non-professional applicators.Coal Tar based products contain aggressive solvents that will dissolve the underlying coating if incompatible (i.e. not another Coal Tar product). These products should ideally be applied by professionals with solvent vapour masks (such as the 3M 4251) and full protective clothing.Not sure what you have?1. Clean a small flat patch of your hull with a mild detergent solution to remove any dirt.2. Take a clean white rag, apply some white spirit and rub it onto the cleaned patch.3. If the rag comes off clean, or with only very faint marks; it's almost certainly a Coal Tar. If it is marked with brown or black staining; it's a Bitumen. Bitumens:- Rylard Rytex and Premium Protection.Coal tars: - Rylard Coflex VT, Standard Black, Comastic. & Epicol CT Epoxy.