Thank you for the advice.

Quite correct, the other resin is polyester.

One final question: is the resin to be brushed onto the fibreglass before being mixed with the hardener and left to dry to a certain extent? It is quite difficult to get a successful mix of the two ,which are vastly different in their densities, prior to application. Taking into account that the resin liquid comes in a tin and the hardener has to be squeezed out of a tube makes things that bit more difficult!