paint system compatibilities

[Thrashsmith]

Hi, this question is on the DIY sort of level...

Can anyone offer any guidance on the compatibility of primers and top coats? I know it's recommended to buy a primer and top coat from the same range so they're part of the same system, but how much can you mix and match? I'm guessing that the stronger the primer the more options you have for a top coat? E.g zinc phosphate primers or an epoxy primers can handle a wider range of top coats than water based red oxide primers or acrylic red oxide primers.

Regarding spray can top coats - I know that they contain aggressive solvents, does anyone have an idea how the solvents affects the compatibilities? E.g would you kiss goodbye to a water based red oxide primer if you went over it with a spray can of acrylic top coat?

Cheers in advance.

 

[richie00boy]

Zinc phosphate primers tend to be xylene thinned and are reactive to high solvent paint.

I've not seen a water based red oxide primer before. I've only seen two water based metal primers and only one of those was automotive.

Overcoating a water based primer with solvent paint should not pose a problem as the water based is pretty inert.

 

[Thrashsmith]

Cheers. It's kinda ironic that the tougher zinc based primers are actually less compatible with spray top coats than the less durable water based primers.

My application is for ornamental exterior hand forged ironwork. Ultimately I want a good primer with a good spray top coat. The spray aspect is kinda essential cos by brush it's damn hard to get the paint right in there into the intricate parts, but it's easy with a spray and the results are nicer.

 

[richie00boy]

Get yourself set up with a mini spray gun, use epoxy primer and cellulose top coat. Enamel topcoat takes longer to dry and stays a little bit soft for days which can result in marks and impressions being left in the finish.

 

[Thrashsmith]

Cheers for the advice!

 

[the snooper]

my advice would be to use 2k top coat if your going for a gloss finish, cellulose more often then not needs polishing and doesn't like cooler weather at all and will bloom like crazy where as 2k applied right will have a great shine without the need for any further work

 

[Daz1968]

I would also say that 2k direct gloss will be a good top coat in this application. Only issue is the safety aspect. Maybe try some 2k epoxy top coat but not sure about its durability, but we do use 2k epoxy on tanks and steel work at work and that is out in all weathers.

 

[Thrashsmith]

Thanks for the advice folks. Satin or matt finishes generally suit forged metalwork better than gloss finishes, anything in those realms you'd recommend?

I came across Rustoleum Hard Hat sprays the other day. I gave customer services a ring as (on top of doing the regular red and black alkyd spray primers) they do a zinc spray primer, "Galva Zinc - a fast drying zinc rich primer based on an epoxy ester resin", which they said is compatible with the alkyd Hard Hat top coats. Seeing as they've got satin and matt blacks spray top coats it seems worth a punt. 20 x the price in the price than your suggested methods I'll bet, but until I can invest in some gear it's probably worth a go.