Sand down or just paint over?

datadiyer · 3 Aug 2020

Hi,
I've have exterior gates painted black gloss by metal fabricators who made them and now there's rust in places after a few months.
Can I just sand down/prime and paint over rust patches, or sand down the whole lot and restart?
Any advice greatly appreciated
Many thanks.

KenGMac · 3 Aug 2020

datadiyer, good evening.

If the gates are as you say only a few months old and have been [presumably] factory decorated, I for one would be questioning the effacy of the preparation of the gates prior to and during the decoration process.

Indeed, there may be a case to ask the fabricator to undertake some remedial work?? depends on your relationship now with them??

Can I ask, how extensive is this rusting? and where is this rust? at the welds perhaps?

Ken.

datadiyer · 3 Aug 2020

KenGMac said:
datadiyer, good evening.

If the gates are as you say only a few months old and have been [presumably] factory decorated, I for one would be questioning the effacy of the preparation of the gates prior to and during the decoration process.

Indeed, there may be a case to ask the fabricator to undertake some remedial work?? depends on your relationship now with them??

Can I ask, how extensive is this rusting? and where is this rust? at the welds perhaps?

Ken.

Hi Ken,

I was told that 'red oxide' was applied prior to a top coat of some sort of paint used for car parts for its effectiveness in preventing rust. I went out to gates earlier and was going to sand down some patches of rust showing through.
I ended up with my disc cutter with sanding disc and sanding most of it down. There are 'bubbles' of rust pretty much everywhere. It couldn't be painted over, even a novice like me knew that. There was no 'red oxide' visable when sanding it down, i presume it's red?
I am friendly with the lads who made them, but I will contact them to find out what they did in regards the painting.
I meant to take some pics, I'll post some up tomorrow.
If you have any advice in the meantime, it'll be most welcome.
Kind regards.

datadiyer · 5 Aug 2020

Why is it that everytime I say I'm going to take a photo to upload, it's starts raining constantly

datadiyer · 11 Aug 2020

So I sanded most of the areas where the bubbles of rust had come through, ready to red oxide it, and withing 48 hours, more rust had appeared. I used a disc cutter with those sanding flap discs.
So I went out and bought some Hammerite red oxide primer and some Zinzeer exterior black satin. I plan to wait for a spell of good weather, then run the sander over again, then apply primer and Zinzeer. Am I doing the right thing to sort this out please? How much sanding do I have to do? Right down to the bare metal?
Any advice is most welcome.
Thanks in advance.

datadiyer · 11 Aug 2020

Also, should I use 'coach paint' as someone suggested to me? If so, any recommendations?
Many thanks.

sparkwright · 11 Aug 2020

You could try something like Hammerite's No. 1 Rust beater, which is a brown primer.

I used this on some rusty gates in 1998. It was then undercoated and glossed. It hasn't been re-painted in 22 years and to this day the rust hasn't penetrated through.

datadiyer · 12 Aug 2020

Thanks Sparkwright,
Well as I've sanded the bulk of the rust off, I'm guessing this is just surface rust, so giving it a quick once over with abrasives should rid of the rust. Please correct me if I'm wrong. I've got the Hammerite primer now and Zinsser top coat, so hoping for the best! 22 years is a good run tho fair play, hope mine last long. I'll post the finished project up on here.....as soon as we have a few days good weather!....thanks again.

Diver Fred · 12 Aug 2020

If you take the finish off to shiney metal then you should prime with an 'Etch' primer. Alternatively (and not so easy now with the wet weather) you want a light but dry rusting of the surface and then use your Hammerite primer. Either will cause the paint finish to 'grip' the metal and so not come away so easily.

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Sand down or just paint over?

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