After the first application of rust aversion paint, I applied a layer of fiberglass on the bottom of the tank in order to provide an extra barrier from moisture in the event the boot sprung another leak. The fiberglass is painted onto the surface. You simply keep applying the rust aversion paint until there is full coverage over the fiberglass. It is important to mention to use only one layer of fiberglass. The reason is after the paint is applied the thickness increases and if any additional layers of fiberglass is applied, it will be a real challenge to get the tank back into it's allotted space. The space is very tight, even with the single layer, it was difficult to get the tank back in.