Aluminium Mast re-painting or ?

[mlydon]

Celestial - it serves as the transition coat, like alumiprep. It’s what interlux calls for, for that first coat. Forms a barrier to prevent oxygen trom getting to the mast, same as water from fiberglass, I suppose.

Matt

[Celestialsailor]

Originally Posted by Rucksta

Interlux sticks well enough to well prepared Aluminium and is hard enough to resist halyard wear.

Without spray application Strontium Chromate is difficult to get coverage without lumps even with two coats.

If all you have is a roller or yard rules make spraying too hard, Barrier Coat is a good alternative.

Strontium Chromate is made especially for aluminum. It is meant to go on thin. So thin that you can still see the aluminum underneath. As far as halyard slap, LPU goes over the primer, so that is what the halyard is slapping, not the primer.
Even if a yard doesn't allow DIYers to spray, it's guaranteed the yard itself does. If the OP did the labor of prepping the mast, I doubt it would take the yard more that 2 hours to complete the spray job.

Again, the method I use was recommended by the pro's at 2 different yards.

[Moonshine36]

I moved a boat from San Diego to Port Townsend, in the spring of 2017. The mast was showing some corrosion and loosing paint in several spots. So on the advice of a well know PT Boat Rigger, I scraped and sanded those areas, wiped it down with Denatured Alcohol, painted the bare spots with zinc chromate, sanded that lightly and recoated any bare spots again with zinc chromate and applied a quality one part marine oil based white paint (two coats). 3-years later she looks good, at any distance, you can not tell where I painted and where I did not. But standing on the boat looking up the mast "I" can see a slight difference in the sheen on the mast up to the first spreader. But beyond the first spreader, I really can not see any difference, she's a double spreader rig with the mast head at 65 feet.
So I would recommend this process if you're only looking at a little / or some paint loss and corrosion.
Ken

[skenn_ie]

Get some Chromate primer on it ASAP, esp on corrosion around fittings. It would be worth removing a couple of fittings to evaluate how deep the corrosion goes, probably refitting with larger rivets to remove most of the corrosion. CHeck VERY carefully for fractures around the rivet holes as they can be quite extensive and may suggest that a replacement mast is called for.

[markvannote]

Originally Posted by CarlF

Good point. I was thinking of just the US market

But I can't remember the last time I saw a new big aluminum Selden mast at a boat show that wasn't painted.

A quick google search for "Selden anodized mast" only turned up dinghy and small keelboat masts.

But I agree that mast length anodizing tanks must still exist in some countries.

Carl and dfelsent,

We, Sparcraft US, have a 70ft ano tank in Charlotte, NC. Up to that length we can do all the cutting, fitting and welding previous to anodization. Selden do offer anodized masts for larger boats. They receive pre anodized sections from Europe (not sure if they are 40 or 50ft) which they then cut, fit and weld. This is why all masts over that length have a splice in it. I am not sure if they produce longer, one-piece, masts which are painted.

One thing I have really drank the kool-aid on with spar finishing is powder coat. We will do somewhat of a prime, not full, anodize and then powder coat. The ano seals the entire tube but still has "tooth" to the finish so the powder coat bonds properly. Having this finish instead of a chemical bond of paint really is quite nice and lasts much longer.

We do not really advertise the service of doing old masts. There are so many variables in the existing finish, who is doing the prep work, etc. We did do an International 6 Meter in powder coat satin black last year but working with a boat yard and the conditions and expectations were extremely clear ahead of time. Someone threw money at a problem and it did turn out very well.

Regarding some of the questions brought up by the original poster, your stiffeners are most likely installed with alloy rivets so you do not have to remove them in order to refinish. Just make sure you have prepped and cleaned every nook and cranny around the heads before the final finish. If there is existing corrosion at those rivets there is a chance that it is within the grip of the fastener, not just the head, and you will want to drill out and start fresh which you can do one at a time. People are mentioning tef-gel when installing hardware which is vital. That or Duralac will go a long way. (tef-gel is much easier to work with) Wherever possible use isolation tape, even 3M electrical tape, between the fittings and the mast. (under a diamond pad eye or the cheeks of a Schaefer sheave box for example) Stick the tape to the underside of the piece and trim excess with an exacto knife. I lost count of how many different products were recommended in this thread and everyone seems to come with some real life experience so you have some homework to do. The one thing I will say, or repeat, is prep is EVERYTHING and doing that poorly will make any product fail.

Apologies if some of this comes off as an ad but I am trying to address the knowledge of what is available in the states versus trying to sell a service to the poster. I also can't help being a bit of a nerd about these things.

Thanks.
Mark

[Cheechako]

If you can strip bare do so and leave it.
I doubt you can get it anodized but that is by far the best solution.
But it's downside is that the aluminum turns grey ish and gets on the sails etc. It even makes your hands grey.
And rebed all that hardware properly. I like Lanolin on SS/aluminum interfaces.
But often all the paint wont come off leaving you a spotted dog.. (stripper maybe for the last bit?)
If you repaint, leave the bottom 6-8 ft bare and you will have far less bubbling paint issues etc.
warning: I had the mast rebuilt by pros in Annapolis on my 47 footer. Stripped, sanded, acid washed, Chromate primer, etc etc . "The whole full meal deal." The problem with this is some masts/boats are pretty "active". They will bubble the coating from the inside. Within 3 years the bottom 6 feet had plenty of paint issues. There was a lot of SS hardware down there and some bronze winches on the mast. That was a wasted $10k +/-

[nfbr]

Originally Posted by Cheechako

If you can strip bare do so and leave it.
I doubt you can get it anodized but that is by far the best solution.
But it's downside is that the aluminum turns grey ish and gets on the sails etc. It even makes your hands grey.
And rebed all that hardware properly. I like Lanolin on SS/aluminum interfaces.
But often all the paint wont come off leaving you a spotted dog.. (stripper maybe for the last bit?)
If you repaint, leave the bottom 6-8 ft bare and you will have far less bubbling paint issues etc.
warning: I had the mast rebuilt by pros in Annapolis on my 47 footer. Stripped, sanded, acid washed, Chromate primer, etc etc . "The whole full meal deal." The problem with this is some masts/boats are pretty "active". They will bubble the coating from the inside. Within 3 years the bottom 6 feet had plenty of paint issues. There was a lot of SS hardware down there and some bronze winches on the mast. That was a wasted $10k +/-

Most of the bubbling is in the bottom 6ft and boom

I'm considering maybe just rubbing that part back and leaving bare, and leaving top paint intact.

[Loon]

7 years ago during the re rigging project I removed all mast and boom fittings I could sanded any areas that had bubbled up or lost paint about 40 different places. This is what I did . Sand corroded areas to bake metal tapering the edges,wipe with alcohol then immediately spray area with rust-oleum metal primer. Dry and recoat then follow up with white glossy rust-oleum after removing taped off areas allowing some over spray to hide the taping lines. Three coats of this . Cost ten bucks . Seven yrs later you can't see any issues other than normal wear/ fading.
Good luck ,my two sense

[skenn_ie]

I have only ever seen anodised masts, mostly gold, and up to 80ft. Boat shows were too long ago to remember.

[sailrjim]

Originally Posted by 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

Another anecdote:

A mast and main boom I built from scratch using aluminum sections total 48 ft. from Metal Mast 30 years ago is chalking somewhat, but still fully coated and in service. At about the ten year mark, a few places had some very small bubbles around ss fasteners on the boom where I did not use enough Duralac, and where the ss sheave box at aft end had creased the paint. Partly refinished and added thin tough plastic sheet between paint and ss sheave box. Would now use Tef-gel or Starbrite at fastenings and thin plastic sheet between ALL stainless steel fittings such as sheave box, goose neck, etc., and spar surfaces.


Original finish scheme: Dry fitted all components then removed. Sanded bare aluminum lightly to debur and ease any slight scratches or dings. Blow off using dry oil free air. Used Alumiprep (mild acidic etchant) followed by Alodine (liquid), then two coats Petit hard epoxy undercoater, then two coats Petit two pack urethane topcoat. All paints were air sprayed in a spar tent using pro equipment. Undercoater white, top coat light grey. Service: Atlantic Coast and Caribbean.
We chose to paint instead of anodize for cost and aesthetics. After all said and done, I do not paint smaller masts unless repainting, opting for the natural anodizing. When repainting, remove paint by best means which may require some combination of sanding, paint remover, blasting depending upon depth of corrosion. Take care when sanding near aluminum rivets. Whenever dealing with bare aluminum, as has been stated by others, must begin the thorough prep coating process immediately and continue to the point that there is no bare aluminum. With good technique and some of the new roll no tip paints, a spray job is not necessary though spray may be faster (not including cleanup of eqpt.) and provide better appearance depending on ability of applicator.


Though I have not yet tried, I have thought of using some of the MCU (moisture cured urethane) primers and top coats such as Sherwin Williams/Seaguard products. Single part, quick dry, wide temp. range, moisture tolerant. Any one have experience with this product? Have experience with the primers on other projects, but not on spars. To avoid hijacking the thread, please redirect if discussed elsewhere.


Jim

[Water Dog]

Got information from Interlux that I couldn't find after diligently searching CruiersForum.

I've been unclear how to sand a 50' aluminum (not anodized) mast and get the primer on quickly enough to avoid the problems cause by aluminum oxide. This post addresses this and a couple of other issues.

I'm using the Interlux system: Interprotect-2000E; Epoxy Primekote; & Perfection, but I think most of this post would apply to any two-part system
I had a phone call yesterday with Interlux about these issues, intending to apply their system: Interprotect-2000E; Epoxy Primekote; & Perfection, a Interlux's recomended solvents.

As I approached the job, I started to wonder how I could apply primer soon enough after exposing bare aluminum
It's well-known that, quickly after exposing bare aluminum, aluminum oxide forms. It's notorious for later causing adhersion failure. That is, the paint/epoxy/LP only sticks temporarily, perhaps two or three years, and I want a result that will last much longer! My 50' mast, with a lot of peeling paint, and signs of corrosion especially near stainless fittings, is in the boatyard on top of rolling sawhorse-type platforms with carpet on top. From what I've read, the alloy of this Catalina 36 mast is likely to be 6061 T6.

Choosing to safeguard our planet, I rejected Alodine/Bonderite
BTW I looked into and rejected Alodine, Alumnaprep, Bonderite, etc., deciding that those products are too ruthless on our dear planet, which I hope will be thriving enough for our grandkids. Those products need too much rinsing for me to contain their harsh chemicals in any practical way.

What Interlux told me (and my comments)
Anyway, I called Interlux ((800) 468-7589). They are available 9:00am-4:00pm Central time in the USA. (Thye might have told me 8:00am.) Here's my understanding of what Interlux told me, combined with my comments. If there's an error here, it's likely my understanding or writing, rather that what Interlux told me.

I was told that many people apply Interprotect to aluminum hulls. The fellow I spoke with left me feeling confident that he was competent and gave information that I could rely on.

Summary: I'll be able to do this myself relatively easily
My overarching take away was that the job will not be as difficult as I feared, but that I need to watch the relative humidity and dewpoint to avoid the risk of salty dew falling on the coatings. If I were not located where salty dew falls, such as in Wisconsin, I could sand to bare aluminum and do the first primer coating of Interprotect 4 days later. But that's not an option for me.

Don't expose a new coating to salty dew
As I'm right next to the ocean (and dew often starts to fall before sunset), I should sand for 4 hours, clean, and then apply the Interprotect, leaving a 2" edge of bare aluminum. Then, for the next section, do the same starting with that 2" edge, without sanding the previous fresh Interprotect. I suppose if it's been more than 24 hours, one could sand the Interprotect.

My take away is that, as a general rule, I should NOT paint late in the day to avoid the salty dew from getting on the still-curing Interprotect. Last night, I found where local NWS forecasts for dewpoint, relative humidity, temperature and winds are all convenient displayed next to each other on the webpage for hourly forecasts.)

Also, I'm guessing that it's better not to wait 4 days if one can. And I'm not sure about dew that has little salt, but I'd guess that's to be avoided as well.

Coating times; and how/when can I turn/rollover the mast for prepping and painting the side on sawhorses?
Interlux agreed that I should wait 3 hours before applying a new coat of Interprotect over a previous coat. I'm in Southern California. If you're in a cooler climate, you may need more than 3 hours between Interprotect coats. Once a coat of Interprotect has dried for 24 hours, I can freely roll the mast over onto that layer (on the carpet covered sawhorses).

Can I apply Interprotect over hard-to-remove old paint in the sail track?
As to hard-to-remove paint inside the built-in sailtrack (part of the extrusion), I was told not to worry if the previous paint is in decent shape if it is two-part paint. (The first owner of the boat installed the main sail on an external furler for easier single-handing that he did twice; California to Hawaii. So, the track has had little use.) The problem is that two-part products tend to dissolve and not adhere/stick to one-part finishes. To determine whether the paint in the sail track is one-part or two part. I was told to test with lacquer thinner or Interlux 202 solvent. No other solvents will work for this test, I was told. Wet a rag with the lacquer thinner or 202, and place it on the old paint. If, after 15-20 seconds, the old paint is coming off, the old paint is one-part paint. If it doesn't come off, it's two-part.

Luckily the old paint on the mast is two part. The boom, which will be easier to bring to bare aluminum, is one-part.

Can/should I use West's system to fill holes that won't be used?
When I asked about filling holes that I won't be using with West system epoxy/resin, I was told that would work well.

How I intend to fill the holes to avoid glops inside the mast that might hang up wires or running rigging
I read this morning that any filler must be made after the first coat of Interprotect. To do this, I intend to turn the mast so that any hole that I am filling is facing downward and tape slippery plastic (HDPE?) over the filling, so that the epoxy doesn't run too much into the mast, where it might interfere with running wires or moving rigging. And, after it cures, might be somewhat fair.

After coaing the mast with Interprotect, Expoxy Primekote and Perfection, will I need to re-tap old holes?
I was told that, as long as I don't slop on the coatings as I go, I don't need to worry about needing to re-tap threaded holes. The screws should go back in just fine.