Help!!! - I got paint problems

A trick I used once when spray paint wouldn't adhere was to go over with multiple very light coats, allowing a little bit of time to dry between coats.
This wasn't on gal so it may not work.

Shane

Hi stevebmi,
I was thinking along the same lines as Shane. I've always sprayed, doesn't matter if on gal or bare metal or even a re-coat, I do it in several light coats that will build up to a better adhesion to the base and then each coat after forming one coat. Applying the coats so that one sticks to the next, if you know what I mean.
Give that a try.
Cheers

Paving paint is in fact a good option, it is a single pack polyurethane that sticks like the proverbial to a blanket.
Quite a few pro fisherman use it to paint steel fishing vessels.
Try a sample.

Steve,
If you're using two pack, like say an epoxy, you need to stay with a two pack system right through, preferably from the same manufacturer, for the whole job.
Two pack over single pack usually does not stick and can blister and turn nasty.
Generally you need to give the gal a bit of an rub with sand paper to get the oxide off and to key the surface. Then use a good two pack etch within an hour or two, followed later by a two pack primer. The primer is what does all the work of protection and adhesion. Then the two pack top coats. I don't think top coats will stick well straight over etch in a two pack system. If it's mixed properly, it should make no difference whether you brush or spray, except that spraying two pack can be very nasty for your health.
All of these two pack products are expensive.
An alternative might be single pack etch and primer followed by stone chip paint or maybe some of that underbody antirust mastic gunk. An automotive rust proffer might be able to spray it on for you.
Good luck with it.

Steve,

I've also used the POR 15 product and find it amazing.

You might just find that if you bite the bullet and use it, you may just save some $$ by stuffing around with all the other options. From memory, it also becomes cheaper when you buy more of it.

CHeers,

Mark

Killrust , my 6x4 garden variety trailer which my dad bought new in 1970 , was gal dipped prior to pickup and spray painted , since it has been in my possesion ,1980 , I have given it a repaint every 10 yrs , allways just a spray over with turps , let dry , then KILLRUST applied with a 3" brush , stuff flows and finds its own level , very hard to tell that spray painting was not used.

Thank you to everyone that have provided me with some tips

I can assure you it has been driving me nuts.

I did some research after posting this thread.

It would appear that it could be a combination of things. Spraying technique like multiple thin sprays I think is part of it, as I could be rushing it a bit (alot). Using a polyurethane such as the Paving Paint, is another part.

I have since downloaded a document from Orrcon.com.au dedicated to protective coating over gal steel. Polyurethane is a good option.

POR 15 is fantastic, I just belted a piece of gal steel i coated last night - perfect but expensive. Because i have to tape everything up it is also a bit time consuming.

I think another suggestion was the primer - absolutely spot on. For anyone else trying to do what I am doing, the cold phosphating pretreatment is possibly a big factor. I was told to wash substrate down with week acid solution. Orrcon and Galvanisers Association do not recommend this. So there is another mistake of mine. I have come to the conclusion that the gal surface requires this special treatment to allow proper bonding of top coat and primer.

Trying to find suitable products as recommended was also a bit difficult, but I eventually found the Dulux Protective Coating Site. I'll be giving them a call tomorrow.

So thank you all for steering me in the right direction, you have all been great.

Don't know why i did not start here in the first place.

I have had good results with penatrol paint the surface with it and also add some to the paint before coating.

where i have had to paint over gal at work i have had to lightly sand over the area will scourer pad , then etch very lightly , then top coat, paint will still come off but not as readily

hi steveibmi
red zinc oxide primer will stick like the proverbial to galv as the galv has zinc in it then use a top coat that uses the same type of thinners or cleanup method
works for me
cheers