Nightmare Paint on gate

[Spark24]

Made a small side gate which is galvanised.

I'm having a nightmare with the paint....

Basically I spray painted it'll with a gloss black (suitable for metal) however on the round bar Infills the paint keeps blistering. Huge blisters off paint that just pop dry and expose the galvanise.

I made sure the surface was preped with a dry cloth before applying first coat.

What's confusing is the flat bar and box sections are fine! No blisters at all but the round bars keep blistering!!!!

Any ideas? Never had this problem before!

 

[ford34/2]

All down to the Primer,years ago we used Calcium Plumbate primers, in todays world maybe a zinc phosphate primer.Maybe an acid etch primer. Back in the good old days, I was taught to degrease bare surfaces with white spirit, and Meths,and then to use Calcium Plumbate Primer as a first coat. It was heavy, and lead, and expensive, but it seemed to work. A google search should throw in a few modern day primers. Many windows were of steel construction and were Galv and painted, never got problems, a lot of up and over garage doors were Galv as well.
There will be some fancy primer thats safe to use, galv is too smooth a finish for paint to stick to.
Stan

 

[Spark24]

I usually use a vinyl paint but it ends up drying a dull/Matt black - which this customer doesn't want!

The vinyl stuff ends up like a wax texture when dry and I've never had problems with it. Unfortunately I can't use it on this job!!

Couldn't believe it when I turned up and it was blistered!!! Worse still I'd fitted it the previous day so it was on-site for the customer to see!

 

[Welderpaul]

Slosh it over with mordent soloution, allow to dry and then paint it. The new galv is reacting with the paint. Mordent solution kills it off.

There are some paints which will go straight over without a problem. We use a few different enamels that can be painted straight on.

Your going to have to strip the paint off first though.

 

[brightspark]

manor paints high build vinyl will coat direct to new galve no need to even wipe it or -prime

 

[Spark24]

Thanks lads. Bloody nightmare.. Look like a right fruit

 

[rtbcomp]

B&Q do a primer suitable for galvanised steel.

 

[ajlelectronics]

POR-15 is perfect for weathered galvanising. It would take an angle grinder to shift it.

 

[the snooper]

there is some 2k acid etch that is also good with galv no isocyanates in it either

 

[ajlelectronics]

Quite. Or epoxy primer for a two stage job. The beauty of POR-15 though is that it is a one coat finish, designed for the purpose.

 

[Kent]

Hi build vinyl will go straight on brush or spray - I think you just need a glossy or more matt one to suit the clients wishes. I like to weather new galv for a few days, don't know why someone must have told me to years back but it seems to work. Galv needs special metal primer for most paints but not the hi build vinyl which can go straight on

 

[Wendelspanswick]

I used to use a mordant solution on new galvanising before painting, it was a pale blue water based product that came in a 5l container. For small items I used to apply it with a brush and for larger items I used to spray it on. It would to turn the bright galvanising a dull matt grey in about an hour, cheap as chips to buy as well.