POR 15

[Lucky]

So, continuing the definitive POR15 thread, I've just started stripping down a fuel tank for prep. It's been painted previously with POR15, but it hasn't adhered to the stonechip rubberised paint that the underside of the tank was originally painted with. Due to the age, there are chip and dings in the tank that have got surface rust despite the stonechip.

Stonechip of course provides some insulation against this (the clue is in the name) and I don't want to compromise the robustness of the tank for the sake of rustproof paint, but I've already seen that the POR doesn't like sticking to the stonechip; it was peeling off in long rubbery strips. Was this just because whoever did the deed didn't prep the surface sufficiently for the POR to adhere? Or should I basically strip it right back to bare metal and start from scratch? And then what? Will the POR be strong enough to replace the stonechip altogether, or should I POR-coat it and then overcoat with stonechip?

Opinions welcome, given how rare fuel tanks are already I want this one to be done right and last a thousand years, lol

[DKWW2000]

In my opinion & experience of such treatments I have found that once the integrity of the surface of any paint, be it anti rust paint/Hamerite etc, has been compromised water gets in & causes rust underneath the paint out of sight

I have always found that Old diesel engine oil mixed with Waxoil/underseal thinned with Derv/parafin/white spirit to allow it to be sprayed on, outperforms any thing else. Any old underseal it comes into contact with is re-juvinated. It soaks into the parts others cannot reach

The downside is it is very messy and needs to be done on a bi-annual basis but it is quick by comparison.

I always wear a all in one cheap decorating suit so it can be wanged after use, a respirator is also advised if you do not like the taste of old oil

It is also (for the greens) environmentally friendly as you recycle the old oil