How to re-paint flaking and bubbling metal letterboxes?

Question

The letterboxes have paint flaking and bubbling paint on both the front and back parts of the letterbox. Internally they’re still good. Can I take the paint of using a grinder with a paint remover attachment then paint with a primer and top coat or do the letterboxes need replaced?

many advice would be awesome!

HardYakka · Answer

Hi MitchellMC,

Thanks for the great advice! I'll do exactly as you've said and it's good to know that it will give a few more years to these letterboxes as it's pricey to replace the lot of them. Thanks again!

MitchellMc · Answer

Hi @HardYakka,

You should be able to tidy these up without replacing them, at least as a first step. What you can do is sand back all the flaking and bubbling areas until you’ve got a clean, stable surface, removing as much loose coating and oxidation as possible. Once that’s done, apply an etch primer, which is important for metal like aluminium as it helps the paint properly bond to the surface, and then finish with a suitable exterior enamel top coat in your preferred colour.

As for whether they need to be replaced, it’s definitely worth trying to repair them first with spray paint. From your images, they look like aluminium and what you’re seeing is likely oxidation under the paint. If that oxidation is being caused internally and pushing the coating off from beneath, then it will probably continue over time and replacement may eventually be necessary. However, if the issue started because the original coating was damaged and allowed moisture to get in, then sanding and recoating should seal it back up and stop the problem.

My suspicion is that moisture is getting in somewhere and causing the oxidation to bloom under the paint, but as a practical and cost-effective approach, I’d start with sanding and repainting. Even if it’s not a permanent fix, you’ll likely get a number of good years out of them before needing to consider replacement.

Please let me know if you have any questions.

Mitchell