Originally Posted by cris

Like yer man above says, it should be alright.
We also use upol etch from a can when doing spot repairs. I mention the brand as halfords and several of our local motor factors do it (easy to get)
As long as the area is not contaminated (oil/grease/finger-prints etc)
if prepped in your garage a reasonably dry day with good temp. eg not raining loads no damp.
and finally the area had a rub down to get a good key your doing the same thing most bodyshops do