Aluminium Mast re-painting or ?

[nfbr]

27yo white painted aluminium mast is losing paint / showing surface corrosion at most rivet / screw points.

I have to replace standing rigging anyway, so it's time for mast to come off and

a) leave raw aluminium?
b) Clear coat?
c) Passivate some other way?
d) Re-paint?

Whats the consensus? I figure the paint will just corrode under again, though maybe not take so long this time.

Thanks
Paul

[BillKny]

Originally Posted by nfbr

27yo white painted aluminium mast is losing paint / showing surface corrosion at most rivet / screw points.

This basically means the stainless hardware wasn’t installed right the first time. Unless it is all removed and installed with Ted-Gel or Duralac you can expect a repeat.

Originally Posted by nfbr

a) leave raw aluminium?

This really depends on the alloy. My last boat had a bare aluminum mast for 40 years, with ZERO corrosion issues. If you do this, you STILL need to properly set the stainless hardware.

Originally Posted by nfbr

b) Clear coat?

This will have no real cost or longevity differences from paint. A HUGE fraction of the cost is (or should be!) in the surface prep before painting. This will be the same either way. If you like clear and shiny, go for it. But to my mind it’s no benefit.

Originally Posted by nfbr

c) Passivate some other way?

I guess you could theoretically have it anodized, if you could find somebody local with a bath big enough... but I doubt it.

Originally Posted by nfbr

d) Re-paint?

I see this coming down to option (a) or (d)

Originally Posted by nfbr

Whats the consensus? I figure the paint will just corrode under again, though maybe not take so long this time.

This is CF, there will be no consensus. If properly prepared, and your hardware attachment issues resolved, a good paint job should last a decade, at least. The catch is finding someone who really know what they are doing.

[Bill O]

Personal preference if you like it painted or not.

The paint looks nice, but is a pain. Our last boat (I made the rig) and didn't paint it. Had that boat ~15 yrs. and never regretted not painting it. It was easy to clean w/white vinegar (if needed).

Current boat is painted and is needing attention. Repainted the mizzen boom years ago and still looks good, but if it didn't have paint already wouldn't have done it again. Stripping it is a fair amount of work and is why we repainted.

Many aluminum boat hulls are not painted for a reason (it is costly to maintain that yachty appearance).

I would vote for plain aluminum (no clear coat) if starting new, but since yours is already painted it's probably easier to repaint than strip it off and bed the hardware better.

[wingssail]

Originally Posted by BillKny

This basically means the stainless hardware wasn’t installed right the first time. Unless it is all removed and installed with Ted-Gel or Duralac you can expect a repeat.


This really depends on the alloy. My last boat had a bare aluminum mast for 40 years, with ZERO corrosion issues. If you do this, you STILL need to properly set the stainless hardware.

This will have no real cost or longevity differences from paint. A HUGE fraction of the cost is (or should be!) in the surface prep before painting. This will be the same either way. If you like clear and shiny, go for it. But to my mind it’s no benefit.

I guess you could theoretically have it anodized, if you could find somebody local with a bath big enough... but I doubt it.

I see this coming down to option (a) or (d)

This is CF, there will be no consensus. If properly prepared, and your hardware attachment issues resolved, a good paint job should last a decade, at least. The catch is finding someone who really know what they are doing.

You don't have to hire someone who knows what they are doing, you can do it yourself after some reading and using common sense.

We've refinished our mast twice in 34 years. The first time (1993) Judy and I did all the work ourselves and used Sterling paint and it looked terrific and lasted pretty well (15+ years).

In 2011 we again refinished the mast, this time we hired a painter to spray it, (after doing all the prep ourselves) but the Acrylic Polyurethane we used this time has not held up so well. It could be painted again now after only 9 years.

In both cases we removed all the hardware and used corrosion protection when re attaching. Corrosion has not been a problem, however oxidation and wear of the finish has been.

[Chotu]

What would you do if you wanted to take a painted aluminum mast and let it go au natural?

Any best process to go that direction?

[searoom]

I’m not sure where your boat is located.
Just north of Falmouth Maine is a soda blaster who does mostly boat work including spars. He will travel but not sure how far. Jim does nice work for Handy Boat Service.
If you can strip all the hardware and have the mast paint cleaned off you can take it anywhere for new Awlgrip.
If it’s pitted it will need to be filled/faired before paint.

Good luck.

[wingssail]

Originally Posted by Chotu

What would you do if you wanted to take a painted aluminum mast and let it go au natural?

Any best process to go that direction?

Not an expert on this Chotu, But I think that most aluminum mast sections and other alloy pieces would be anodized originally before original painting.

So you would probably have to worry about damaging or removing the anodization while removing the paint.

But maybe the bare aluminum's natural corrosion would protect the surface once it forms a layer.

I'd think thorough sanding to get a uniform bare surface would be required.

But sanding in preparation to painting is not that hard and does not need to be that thorough.

[johnn33]

This article is relevant
https://www.practical-sailor.com/boa...-look-like-new
John

[anacapaisland42]

Sand down rough spots
Rustoleum (oil based)
Mine has lasted 30 years with minimum touch up (slapping halyards)
Bill


d) Re-paint?

[zstine]

Chotu: going au natural...
I would not soda blast to go back to natural aluminum b/c it would result in a rough surface. Sanding has the same issue, but probably less so. I have polished aluminum swing arms on motorcycles, which is a lot of sanding... finer and finer grit until you can compound and polish. Obviously you don't need a mirror shine on a mast, but even getting up to a 400 grit would be a PITA on a mast-sized project. I'm guessing you need to get to something around 400(?) to prevent cleanliness issues, which can lead to more problems.


So... with all that said, I would try really hard to find a chemical paint remover that would not abrade the finish of the aluminum. I don't know what paint is on there and I don't know if there are any chemical paint removers that work on 2 part, epoxy based, paints?? anyone??

[JRSHAW]

We painted ours - so glad we did
Looks great
Prepped it properly
Used tef-gel for parts

[Bill O]

Originally Posted by wingssail

Not an expert on this Chotu, But I think that most aluminum mast sections and other alloy pieces would be anodized originally before original painting.

So you would probably have to worry about damaging or removing the anodization while removing the paint.

But maybe the bare aluminum's natural corrosion would protect the surface once it forms a layer.

I'd think thorough sanding to get a uniform bare surface would be required.

But sanding in preparation to painting is not that hard and does not need to be that thorough.

Usually there is a tie coat (zinc chromate, etc.) before painting aluminum. And if you were going to strip off the old paint, you would want to re-apply a tie coat for the paint to stick well.

I've used epoxy chemical strippers (automotive) in the past to remove paint from smaller spars (booms). Not hard, just messy and would think a mast would be easier to get done w/a soda blaster and get a smooth finish (still possible to diy).

After stripping would let it oxidize "au natural" unless you want to go thru the painting process again and again (depending on how long you keep your boat). The bare aluminum will clean up w/white vinegar.

[searoom]

Originally Posted by zstine

Chotu: going au natural...
I would not soda blast to go back to natural aluminum b/c it would result in a rough surface. Sanding has the same issue, but probably less so. I have polished aluminum swing arms on motorcycles, which is a lot of sanding... finer and finer grit until you can compound and polish. Obviously you don't need a mirror shine on a mast, but even getting up to a 400 grit would be a PITA on a mast-sized project. I'm guessing you need to get to something around 400(?) to prevent cleanliness issues, which can lead to more problems.


So... with all that said, I would try really hard to find a chemical paint remover that would not abrade the finish of the aluminum. I don't know what paint is on there and I don't know if there are any chemical paint removers that work on 2 part, epoxy based, paints?? anyone??

PTI makes something called Aircraft Paint Remover.
Comes by the quart from Aircraft Spruce.
Be sure to wear protective gear and good mask.

[nfbr]

Originally Posted by JRSHAW

We painted ours - so glad we did
Looks great
Prepped it properly
Used tef-gel for parts

When you say tef gel for parts
Did you remove every screw and rivet?
Spreaders? Reinforcing layers etc?

[CarlF]

You have to remove all the stainless. Aluminum rivets could stay but they are so easy to drill out that most do.

Only small masts are anodized these days. The EPA made the anodizers switch to smaller tanks to reduce air pollution 20 years ago

Nothing wrong with bare aluminum but it looks much worse than anodized aluminum. Most people end up painting.

Once you have the hardware off painting goes really quickly. No reason to use a stripper, just sand it off. Won't take long on a mast. You need to sand everything anyways to get the oxide off. Because aluminum forms a new oxide very quickly, it's important to prime quickly after sanding.

Painting aluminum is not rocket science. You can even get very good results with Rustoleum spray cans. First use their special etching aluminum primer. Follow the instructions exactly putting on two light coats just minutes apart. Once you have a primer sticking the top coat is easy. Since a mast is small, spray cans are often the most economical way to go for someone without professional spray equipment.

Then use tef-gel anyplace you are letting stainless touch the mast. The stuff's amazing.