Painting over paint

[Chotu]

My mast is painted white and the paint is in decent shape.

Can I just scuff the paint and paint a black coat of paint over it so it goes with the rest of the boat’s color scheme?

Trying to maximize the number of things I can get done this winter so the boat can be sailed.

[tkeithlu]

"Results may differ." There is the chance that the new paint will not adhere well or react with the old, but I think that the odds are in your favor. Sand it, and if the adhesion still seems good, I would proceed. It will help if you use the same type paint, even by label, if you know what was used originally.

[Tetepare]

Good call on same type of paint.

Wash the whole mast before you scuff it up. Try doing a small section first, it would be a bear to strip a whole mast.

[rslifkin]

If you know what the old paint is and it's well adhered, you can likely find a paint that will go over it just fine. Even if you don't know what it is, avoid 2 part paints and you'll likely get away with it.

[gonesail]

definitely wash and scuff all surfaces. test small area before proceeding. if painting in winter watch the temperatures.

[Chotu]

There is no way for me to know what kind of paint is on the mast. It’s a used mast. It’s from Europe originally I think. Seems like two-part polyurethane paint. It’s a very tough, industrial type of finish. Over aluminum. So, I think I can just scuffed it up a little bit with a fine grit sandpaper, and put something else over it. I’m glad the consensus is that might be OK.

Any tips as to what might be a good paint to use? One part? But something that is tough and similar to the paint that is on it? I know it will never be the same as two part, but kind of tough would be good. You know how Masts can be nicked.

[Rucksta]

Chotu

There are single pack poly-urethanes on the market that are brushable and self priming over Alloy.

I used the marine product from Crystal Paints on a mast three years ago and it's holding up well. https://www.crystalpaints.com.au

Boatcraft has a water based 2 pack poly that goes on over cured single pack products without blistering.
Any bare alloy may need priming.
https://boatcraft.com.au.

Maybe you can find something similar locally.

[chris95040]

Originally Posted by Chotu

You know how Masts can be nicked.

On that note I think I'd be inclined to try a 2part poly on a small section. In my experience (interlux perfection vs brightsides) the two part was significantly more durable.

[Chotu]

Originally Posted by Rucksta

Chotu

There are single pack poly-urethanes on the market that are brushable and self priming over Alloy.

I used the marine product from Crystal Paints on a mast three years ago and it's holding up well. https://www.crystalpaints.com.au

Boatcraft has a water based 2 pack poly that goes on over cured single pack products without blistering.
Any bare alloy may need priming.
https://boatcraft.com.au.

Maybe you can find something similar locally.

An important detail. I’m not painting over aluminum. I’m painting over paint. Like the thread title says. So essentially, I’m painting over polyurethane plastic.

[Rucksta]

Originally Posted by Chotu

An important detail. I’m not painting over aluminum. I’m painting over paint. Like the thread title says. So essentially, I’m painting over polyurethane plastic.

Is this the mast to which you will be adding a six foot extension?

How will you achieve that without localised disturbance of the existing paint?

[Chotu]

Originally Posted by Rucksta

Is this the mast to which you will be adding a six foot extension?

How will you achieve that without localised disturbance of the existing paint?

That’s not what the thread is about. That’s a different thread. This is about painting the entire mast. It is currently white. It needs to be black.

[fourlyons]

One of the standard ways to test for good paint adhesion is to paint a test area, let it cure. Score it with a razor blade in a grid pattern with 1/8" squares. Press a piece of tape on to the grid and rip it off. If the adhesion is good none of the squares will come off.
You can use this test to check your preparation of the surface and for paint to paint compatibility.

[wingssail]

Originally Posted by Chotu

My mast is painted white and the paint is in decent shape.

Can I just scuff the paint and paint a black coat of paint over it so it goes with the rest of the boat’s color scheme?

Trying to maximize the number of things I can get done this winter so the boat can be sailed.

Scuff yes, sand? Be careful. If you break through to the aluminium then you'll need acid etch, primer, and top coat. Aluminum starts to oxidize instantly once it is exposed to the air.

i've had success where we wet sanded with running water then applied a water based sub-primer while still wet.

[Uncle Bob]

Some paint pro's will scuff a sound undamaged surface with coarse synthetic pad similar to a scouring pad, don't know the manufacturer but is available in various forms with different densities.
Also be aware that black will get hotter than white, so if the underlying white has any even slightly dubious patches with reduced adhesion there may be problems with keeping the black on.

[Fore and Aft]

Chotu a client of main got over 10 years out of there mast paint with this product. We are coming up 5 years on our mast and are happy. The gloss has gone but the paint is holding up well.
Cheers
https://www.dulux.com.au/products/details/31a