G4 would be best applied on bare wood as it is a deep penetrating product.
You could try a web search but you might find it easiest to buy from a Koi carp specialist or garden centre. I know this sounds confusing but G4 is sold under many guises & for many uses.
It is also applied in an unusual way - when the first coat is tacky like sellotape you apply the second & so on, this means the recommended 3 coats is applied in a short period = job done. Very good product
