Hi,
Anyone tried using aluminium self etching primer on GRP? Just that I have some Hammerite stuff that's water based.

GRP doesn't need etching, flat it down and use normal primer.

The only reason to acid etch GRP is if you really want to F up your lungs LOL
Otherwise just sand and spray!!!
Only problem would be if you use epoxy 2 pack on polyester GRP- the old polyester / epoxy bonding thang being a problem.... But then your lungs won't be a problem cos you'll be using the full breathing gear!!!

Polyester / epoxy works but not particularly well without a sealant in between.... Though I'm sure people still don't bother!!!

I find roll ups best for that