Hi There, I have these 4 post that hold up a shaded awning. I live by the sea and i noticed parts of the beams are corroded. I treated these 3 years by cleaning them and using rust kill etc. However the rust has come through again. I want to do this right and seek your guidance and instructions what to do step by step. * Note the paint now is starting to leave a layer of powder on the surface of the paint, that comes off in your hands. See photo 1. * Photo 2 shows the extent of the corrosion damage. Only on the bottoms. Not sure why as there is good drainage, and these beams are on the roof of the house. * As you can see with the corrosion, the paint removed has left a depth gap between the top paint and the steel surface. How do i apply something that will level the surface. * Can you outline the treatments and preparation required to do this job one time only.

Good Evening @Miczam

I am heading down the track of stripping the post back to bare metal and redoing it. The base of the posts would be wise to have checked to see if they still retain structual integrity as they look pitted. On teh surface it looks like it should be ok, but there is no point in going to the effort of removing all the old paint and rust only to find the base is rusted through. If any of the pit holes are all the way through Its a very short decision tree and needs to be replaced.

Failure might be because of the method, types of paint used, timing of the method (too long between stripping/cleaning the posts back and then protecting the paint or where you live. Even a mixture of all of the above. First step would be to assess the posts, then strip to bare metal all over. Then rustproof and then paint with a compatible paint to the rustproof paint. I know I chose a white very thick rust proof paint for some metal posts that did not get along well with the paint I used around it.

Dave

Nailbag

Hi @Miczam

At this stage the corrosion appears to be still superficial, though starting to show signs of deeper pitting. And without knowing how thick the poles are, then it's impossible to actually give any indication of potential life even with proper restoration. It's possible that the steel isn't up to the salt air and may need to be of solid galvanised.

Before doing any cosmetic work, I would get a domestic structural engineer to have a look over a registered builder who probably wouldn't be interested. They will be able to advise next steps.

Nailbag

The corrosion is still surface and has not penetrated the steel and the structural is in good order.

That is why i am seeking bunnings expert advice on the process now to seal and treat the area.

So can bunnings n9w provide me with the following basis the structural is sound.

Prep work required and how.
Applications to use and steps to be taken
Other steps

Hi @Miczam,

Unfortunately, this level of rust is not what would be typically classify as surface rust. Surface rust usually looks like light speckling or superficial oxidation that can be easily sanded or abraded off without affecting the steel underneath.

From your images, it’s evident that the steel is significantly degraded and being eaten away. The rust has caused material loss, as shown by the large flakes coming off the post. While we don’t know the exact thickness of the post wall, this advanced corrosion suggests a substantial portion of the metal has been lost. Any reduction in thickness directly impacts the structural integrity of the post.

Because of this, it would be unwise to simply apply a cosmetic treatment or sealant. This kind of damage goes beyond surface-level rust and requires a professional structural assessment. Covering it up without addressing the underlying issue risks further deterioration and potential safety concerns.

I recommend having a qualified structural engineer or corrosion specialist inspect the post to determine the best course of action moving forward.

Please let me know if you have any questions.

Mitchell

Hi There,

I have already had advised from the builder that has undertaken renovations that the beams are structurally sound. The beams are a feature more so and carry the weight of a wire mesh awning and is not load bearing. In addition, despite your previous advice, the steel beams corrosion is only surface at this time.

Hi @Miczam ,

Thanks for the update and the additional context. To work with the assumption that the steel is structurally sound and you want to proceed with treating the corrosion, here are the practical steps you would need to follow to properly prepare and coat the area:

First, all the rusted and loose material must be completely removed. This involves grinding out the affected sections and wire wheeling the surface using an angle grinder to get down to clean, solid metal. Any remaining rust can then be treated with a rust converter to stabilise it and prevent further corrosion.

Because the surface will be pitted and uneven where metal has been eaten away, you can use a builder’s bog specifically designed for metal surfaces to fill those depressions. After it cures, you’ll need to sand it smooth to create a uniform surface.

Next, the entire area should be primed with an etch primer such as SLS etch primer, which helps paint adhere well and offers additional protection against rust.

Finally, you can apply your chosen topcoat paint over the primed area. Where the rest of the posts that haven't rusted, you just need to scrub them down with a scourer to remove an oxidisation.

This process is quite involved and requires the right tools and materials to be effective. Also, remember that this approach addresses the symptoms rather than any underlying structural concerns, so continue to monitor the post regularly.

Mitchell

ok thank you.So i have the following items.

bondall Ranex Rustbuster. Apparently this removes rust and cleans area.

And

Dulux metal shield rust defence - Protects against rust.

Can you advise what best SLS etcher i should get.

What other products do i need and are these products good to use.

Afternoon @Miczam

You will need to remove all of the old paint from the post, not just the rusted parts. The way you describe the paint surface coming off means something hasgone wrong with the application at the very least so the whole post needs to be brought back to bare metal and then rust proffed and painted. (All within a short period of time as in days)

Dave

The non affected areas, the paint is a little powdery. No Paint failure. I thought i could sand back only and then apply a sealer first before painting over. Is that correct.

Hi @Miczam,

If you are using Dulux Metalshield Rust Defence, then on any rusted areas, you need to apply Dulux 1L Metalshield Rust Defence Primer instead of the Rainbuster convertor. The Dulux primer has a rust convertor in it already.

That's all you'll essentially need apart from the products to remove the rust and for application, like paintbrushes.

Remember you're PPE, though, with safety glasses, a face mask, gloves, a long-sleeved shirt, trousers and enclosed shoes. The primer/convertor is an acid, so you need to take care when applying it to the rusted sections.

Mitchell

Afternoon @Miczam

Paint stripper, and be prepared with safty equip as the stuff burns. Make sur eyou have drop cloths down as well. The metal will want to rust straight away after using it I would think so be prepared to do maybe a post at a time. I have also used a paint scraper with the paint stripper and a brush for a drill. Its a bit of all and sometimes just one.

Dave

Hopefully @Dave-1 can respond to your question.

I would be of the opinion, that unless those areas are flaking and bubbling off, there is no need to remove all the paint. The residue on your fingers after wiping the paint is oxidation and the breaking down of the very top layers of paint. It's not an indication that the paint is entirely failing. Typically, it's recommended to scrub the paint down with a scourer and Sugar Soap to remove the residue and then flush with clean water. After that, you can coat over the surface.

Mitchell

Afternoon @Miczam

Considering the powdery effect was one of the things that was concening you I would err on the side of caution and remove the paint back to base. No point in going to the effort of sanding and then painting over without knowing why its powdery in the first place.

Dave

Dave, The paint has been there for 5 years and looks good still. It is only a little powdery where you wipe it with your fingers. You could be right however over the whole area there isnt any failure, like paint flaking etc. So i am cautious but i think i will give it a good sand back, wash with sugar soap and rinse off. Any thoughts.

Afternoon @Miczam

:) I always have thoughts, you sound like you have a path to work through and thats what you need. We all have the paths and we can take bits of this suggestion, bits of that suggestion to end up with the path we are happy with. My sweet spot is once I have made my way through the path and look back… Thats when I smile and know I have done a good job. Much like that colourbond dude that steps out of his house to pickup the pape rand thn stands there admiring the roof :)

Be confident, there are loads of infor in this thread. Read the cans of whatever you use (I spend hrs re-reading the products in store) and take photos :) Never too many photos are taken.

Dave

Mitchell I am at your site can you confirm if I need the metal shield etch primer as well as the metal shield rust primer 2 in 1 . Please urgently advise v

@MitchellMc

Just tagging your for @Miczam

Dave

Hi @Miczam,

You only need the Dulux 1L Metalshield Rust Defence Primer.

Mitchell

Noyade

"the paint removed has left a depth gap"

Are you saying that 'gap' is due to the loss of the paint thickness?

Just outta curiosity, if you got a centre point punch and a decent hammer - smack the punch in the circled areas. See what happens.

When your builder saw this - what did he/she suggest as a solution?

EricL

Hello @Noyade

Let me tag @Miczam for you to make them aware of your question.

Eric