A couple of years back we had a terrace built at the rear of my wife's house in Korat. The cheapskate builder only used a very thin coat of paint on the bare metal and now it's flaking off and there's rust on all the joins that were welded. So I want to fix this up. What I was considering is getting a local worker in for a couple of days with an electric drill and a wire brush attachment on the drill, to buff off the flacky peeling paint and buff back the rust to the bare metal. Then we can repaint.

Do I need to use a rust resistant primer/undercoat first, and then another coat of paint? Or would one coat be sufficient. If I use a rust resistant primer, is it available as a flat matte black? If so could we just apply that thickly and be done with one coat.

Appearance is not the main concern here. I just want to get rid of the rust and the flacky paint, and get it looking nice again.

It's always a good idea to use primer. It gives a base coat for the paint to adhere to, and prevents bleeding through. It's metal so no porous surface like wood to seal, but still a good idea as it further prevents rust from starting again. Lot of humidity here so rust happens. Wanted to add, the same thing happened to my porch 2 years after the builder finished, along with house paint fading because of the sun and rain extremes.

Edited 1 hour ago1 hr by fredwiggy

Save time with Glipton 2in1.

37 minutes ago, fredwiggy said:

It's always a good idea to use primer. It gives a base coat for the paint to adhere to, and prevents bleeding through. It's metal so no porous surface like wood to seal, but still a good idea as it further prevents rust from starting again. Lot of humidity here so rust happens. Wanted to add, the same thing happened to my porch 2 years after the builder finished, along with house paint fading because of the sun and rain extremes.

Thanks for your reply.

15 minutes ago, stubuzz said:

Save time with Glipton 2in1.

OK, thanks for that info. I just looked up Glipton 2in1, a 3.5 litre can of matte black is around 600Bt, so that seems ideal, could do the lot with one coat.

46 minutes ago, fredwiggy said:

It's always a good idea to use primer. It gives a base coat for the paint to adhere to, and prevents bleeding through. It's metal so no porous surface like wood to seal, but still a good idea as it further prevents rust from starting again. Lot of humidity here so rust happens. Wanted to add, the same thing happened to my porch 2 years after the builder finished, along with house paint fading because of the sun and rain extremes.

More likely it is the poor aluminium paint they use, and no proper primer. That is what they used with us too.

They repainted it again after 6 years now with aluminium paint when I was not there, of course. Cheap labour, and they think they are saving me money by doing what they do when I am not around.

Galvanized iron needs proper surface prep first. Clean it, roughen it a little if needed, then use a primer made for galvanized metal, followed by a good zinc-based paint. Normal paint straight on galvanized metal often does not grip well, and that is when you get peeling, flaking, and rust coming through later.

2 minutes ago, Hummin said:

More likely it is the poor aluminium paint they use, and no proper primer. That is what they used with us too.

They repainted it again after 6 years now with aluminium paint when I was not there, of course. Cheap labour, and they think they are saving me money by doing what they do when I am not around.

Galvanized iron needs proper surface prep first. Clean it, roughen it a little if needed, then use a primer made for galvanized metal, followed by a good zinc-based paint. Normal paint straight on galvanized metal often does not grip well, and that is when you get peeling, flaking, and rust coming through later.

Yes, I didn't notice the paint they used but it was crapola. Thailand does have extreme weather and wood used always fades fast, so proper preparation and the best materials will have the finish lasting longer. My house is concrete but the paint they used, and primer, was definitely not as good as the paint I used later.