Fairing an aluminum mast

[heartofgold]

I have read all the posts I can find about painting spars, including the very detailed on by George, as well Tim's recent boom painting project. But neither of these projects required fairing. I have some very substantial (aesthetic, not structural) dings on the lower part of the mast which will require some fairing. What products do I use for this, and at what stage will I use them? Along the same lines, what is the best way (short of welding) to plug old holes in a mast?

[Tim]

Doug,

I'll try to post more later, but this might get you going. Check out the application guide at Awlgrip.com. Reading this might be a little confusing, so later I'll post what I would do if I were fairing aluminum and using Awlgrip.

Aluminum Preparation for Awlgrip: Application Guide

As to filling holes, there's no reason not to use epoxy. That is what I shall do this fall.

[Figment]

Is it worth using aluminum powder as a mix-in?

(thinking in terms of uniform hardness when it comes time to fair, or if that location were ever to be drilled and tapped for threads in the future)

[Tim]

Is it worth using aluminum powder as a mix-in?

Hmm...I hadn't really given it thought, but perhaps it would make sense. I'm not really sure whether it would make any tangible difference or not, although the aluminum powder is normally intended just as an additive for plain epoxy coating of surfaces and to add some moisture and UV resistance. I don't think adding some to filled mast holes would be a bad thing, but I don't either know if it would improve it at all.

However, I think avoiding redrilling and tapping the filled areas would best be avoided no matter what, unless the new hole was larger than the original.

[Dave, 397]

If you will be wanting to redrill and retap a hole that is for some reason unworkable, and if it is going to bear any load at all that would be bad to lose, you better weld, grind and THEN fair, I think.

Another thought, if you want a metallic, hi-strength filler, is an autobody filler product called 'All-Metal' (not to be confused with the Meguiar metal polish of the same name). It is, yes, polyester based, but it is also very strong and kicks off fast. If you do not need the additional super-incredible last bit of epoxy strength and do also need something that has very high viscosity but is workable once cured, then this might be the stuff for you too. Just a thought, at least.

dave

[heartofgold]

Thanks to you all for the replies (I would have responded earlier, but I have been snowed under, which is odd for Florida at this time of year). Yet, in spite of the weather, my primary concerns with fairing the mast are:

A) How do I prep the aluminum for the best bond (with the fairing material)? and

B) What fairing product(s) do I use which will work with the aluminum etching and and priming preps?

And, Tim, thanks for Awlgrip's aluminum prep guide. I often stay up late at night reading and re-reading their publications. That particular one is one of my favorites. On the other hand, I am interested in hearing how you would do it (I presume that Glissando's mast will need at least some fairing before you paint).

Doug

[Tim]

When the term "fairing" is used in Awlgrip nomenclature, it's referring to the more substantial, heavy applications of fairing compound that might be needed on, say, an aluminum hull prior to painting--you know, to fill and cover seams, welds, or unfairness in the hull plating.

Filling random holes, dings, or scratches does not, to my way of thinking, constitute heavy fairing. Therefore, let's not go overboard with the process.

Assuming you choose to use Alumiprep and Alodine in your process, here's what I would do with an old spar that required what I would consider to be the usual amount of hole-filling and minor fairing. This process will end up requiring some surfacing--the regular primer coats might provide enough, but it depends on how deeply the sandpaper cuts into the metal, and how much the primer actually covers. I think most older, raw aluminum masts probably require this process, as they may have vestiges of anodizing coating that should be removed. The grinding process in this procedure would take care of that.

The process that follows is an amalgamation of my own preferences and experiences, the information in the Awlgrip application guide, and the experiences of George and Brock here on the board.

1. Wash and degrease mast with detergent

2. Grind mast to clean, bright metal with 36 grit sanding discs

3. Apply Alumiprep 33 as directed

4. Apply Alodine 1201 as directed

5. If spraying: apply coat of 30-Y-94 Chromate primer as directed. This particular process, according to Awlgrip, has no provision for applying coatings without the use of spray equipment, but it seems that you could also use 545 primer instead of the Chromate primer. I believe this is how George proceeded, though

In this case: apply 2 coats of 545 gray primer, waiting the appropriate time period between coats and using no rollers because of the possibility of the 36-grit rough surface snagging fibers and possible causing problems down the road (see Awlgrip guide). Depending on how you choose to proceed in later steps, it might be worth it to apply additional coats of 545 primer at this stage, to ensure that you will never sand through the primer during later fairing processes.

6. To obtain the best overall finish and results, the surface should be coated with a high-build primer. The proper primer, Awlgrip yellow High-Build, is spray-application only, but you could probably get away with applying several more coats of 545 to provide the buildup required for subsequent steps.

7. When primer is dry, it's time to fair and surface as necessary. Fill holes with your desired product and fair and/or surface as required. Seal the surface after fairing with more 545 primer over the entire thing.

8. Sand primer and apply topcoats.


Alternatively, you can choose to paint without using the chemical etching treatments. In this case, sand with 36 grit paper to clean, bright metal, and then apply the 545 gray primer directly over the sanded surface. Then, fill/fair/surface as required, reprime with 545, and apply color coats.

Given all this info, and the fact that there is an Awlgrip-prescribed process that involves brushing the 545 and not using the chemical treatments, I think in your case you might well be best served going the simpler route. Besides, I think that this process--System 1 in the aluminum section of the Awlgrip application guide--most closely matches what you need to accomplish with your mast.

There's little doubt that the best process includes using the chemical treatments and chromate primer. However, lacking the ability to spray-apply material, you must choose to use 545 primer instead. Therefore, this calls into question whether it is better to deviate from an Awlgrip-approved process and use slightly different materials (as in my numbered list above), or whether to stick to what they say and simply sand, prime with 545, fair/surface, and paint.

I have spray equipment, so I plan on following my numbered list process (above) fairly closely. I am as yet unsure how much or what type of surfacing product I will use. I expect that I will go ahead with the two coats of yellow High-Build epoxy primer after the Chromate step, after which I will do whatever fairing or filling is required (filling is more accurate), spray 545 primer over the top, and then topcoats.

This post is a bit rambling, as I was thinking on my feet, as it were. Let me know what I need to clarify or expound upon.

[Tim]

...but I have been snowed under, which is odd for Florida at this time of year

Oh, and...huh????

I expect you wanted one of us to bite, so there you have it.

[dasein668]

I have a question:

Why not use a series of decreasing grits from 36 down to, say, 120 before doing the etching and chromate priming? Wouldn't that make subsequent smoothing/fairing with the high-build primer easier? Or is the high-build primer so high-build that it isn't necessary?

[Tim]

I believe the 36-grit process makes sense, since you need the "roughness" of the 36 grit scratches to ensure proper bonding between the materials. While my inclination, had I not read the process first, would also be to proceed through progressively finer grits in the hopes of minimizing scratches and making the paint smoother more easily, far be it from me to question the paint company's recommendations for bonding the paint.

Paint bonding to aluminum is a difficult process, and I think it makes sense to follow the proper procedure. Paint systems like Awlgrip are carefully engineered based on preconceived steps, products, and the overall system working together. Any variations or departures from the prescribed process bring with them an increased chance of overall failure. This is why Awlgrip is a "professional application " product. The need to use specific products and processes is high to ensure overall success. It's a complex system, and one that takes unkindly to meddling. I can say that nothing matches Awlgrip for looks, durability, and longevity if it is done correctly.

Don't forget: we're talking covering those 36-grit scratches with a coat of chromate primer, 2 coats of 545 primer (which is relatively heavy and good at gap-filling in its own right), and then two heavy coats of the high-build primer--all before even fairing the mast. Then, after whatever surfacing and fairing there may be, there are a couple more coats of 545 to be laid on before painting. It seems that there's plenty of gap-filling ability here in all these coats of product. We'll see.

I don't intend to deviate from the process, but since I've not yet worked the whole process myself, my final judgment will have to wait till I've been through it using the products described. I can say that the "Aluminum System III" process, the quick, one-day process for new aluminum that I used on the boom, worked as directed and with excellent results, applicator error notwithstanding. Awlgrip products are too expensive (and work too well when properly applied) to warrant any attempt any application other than that which is carefully described in the application guide.

I have a feeling the high build primer is quite high build, too. I think it's actually thicker in the "heirarchy" than the Awl-Quik surfacer, which was plenty thick, let me tell you. Besides, the sort of scratches created in metal vs. wood or fiberglass are much milder overall, and fill more easily. It's more about clean, bright metal with an appropriate texture.

I'll find out soon enough, I guess.

[The Good Goose]

I faired my mast prior to priming with good results. I sanded to bare metal any areas needing fairing and used thickened epoxy. I then sanded with 36 grit and primed with an almost clear yellow tinted aluminum primer specified by awl grip and then two coats of 545 primer. I lightly sanded the 545 and then painted. I didn't require any highbuild primer and the job came out perfect.

there are several scenarios for aluminum in the awlgrip manual. If I had to do it over again I would probably go with the wash rather then the clear yellow primer. I spoke to a rigger and he said they don't use that primer because it is not as hard as the paint and the awlgrip dings more easily. At any rate I am extremely happy with my mast as is.

Brock Richardson

[heartofgold]

As usual, everyone here provides excellent information. My main interest in fairing is that all around the mast at the base are about 50 little dings. It looks as if a previous owner was using a hammer to remove the base plate. I guess I never considered that high build primer would sufficient to fill these indentions, but I supose they would do a reasonable job of that.

I have, however, repositioned some hardware on the mast, and need to fill the holes left behind. Is welding the only option, or could I consider some sort of epoxy/fairing compound?

[Tim]

Epoxy is fine for those small holes, as I mentioned earlier in this thread.

[bcooke]

Hey Doug, I for one, am still waiting for an explanation of the "snowed under" comment.


Rain, I would understand. Have you been able to paddle through your living room in your dingy yet?

-Britton

[bcooke]

or rather, dinghy... <note correct spelling>

-B.

[heartofgold]

Sorry of this comes across as a lame explanation, but I was speaking figuratively. You see, I work at the navy base, arranging travel for local military civilian personnel on business and leave. Because of the impending storm, things at work were unusually busy. On top of that, September 1 we changed the whole way we do business, and I was ?snowed under? re-programming our scripts to accommodate all the changes. About a third of those changes were rescinded on Friday morning, meaning I had to undo everything I had done over the previous 2 days. Our company has a ?no overtime? policy, which is not to say I was not paid for my time, but that I was expected to have all the work completed within 40 hours.

Sorry if I bored you with my explanation, but you asked. We were fortunate in that here we missed all of Frances's wrath. We had winds yesterday around 15 knots with occasional gusts to 25, and not a drop rain. I hope our friends down in central and south Florida faired as well we did.

[robbh]

Doug,

The military never changes! What humors me is that the contractors that work for the man, fall into the same crap that us currently enlisted folk have to put up with. The moment you used the word "rescinded" I knew how you felt. Sorry you have to put up with the same B.S., but you were one of us once; Weren't you? Hope things are going better. Take care.

Robb

[heartofgold]

For those of you who have been anxiously awaiting my reply regarding my mast fairing and painting, the process is finally underway, and nearly finished. I have sanded the mast (and boom), applied Alumiprep, Alodine, 30-Y-94, and two coats of High Build--all since Sunday morning.

Tim, when you were suggesting that I may not need to really do much fairing after I applied the High Build, I just didn't get it. Now that I have applied this primer, I understand just how much "build" it delivers. There are still several spots which will need to be filled now, but not like before I applied 2 coats of HB, which took care of most of the smaller scratches. here are 2 shots of the mast, before and after primer.





Not done yet, but certainly getting there.

[Commanderpete]

Looking good.

What an animal that guy was hammering at the mast trying to get the casting off. But, after spending six hours trying to break out that fused casting on my boat (without breaking it) I can understand the frustration.

About sanding the mast with 36 grit---am I just trying to give the mast "tooth"? Or am I trying to sand off the anodized coating? If so, how do I tell when I've sanded it enough?

Thanks

[The Good Goose]

I sanded my mast with a 8 inch variable speed grinder with a flexible backing pad until it was all shiny metal. I tried it first with my Dewalt 5.5 inch orbital sander but it didn't bring the metal to a high shine.

I think you are trying to acheive a surface free of any corrosion with this approach. I also believe you can use the wash and less sanding. If you have access to a 8 inch grinder the process goes remarkably fast. I think it only took about an hour for the mast and another hour and a half for all the fittings boom and spinnaker pole.

I found the Awlgrip manual a little confusing but after rereading it several times felt I had a hand on the process I wanted to use. There are several different approaches detailed so it is more of a question of deciding which one to use and then following the instructions meticulosly

Brock Richardson

[heartofgold]

Yes, what an incredible animal indeed. That actually happened before I began the resoration work on the boat, when I was removing the base to have it welded, nearly 2 years ago. It would not budge, and it took a carelessly wielded hammer to convince it otherwise (the only limitation to fitting a square peg in a round hole is the size of your hammer).

I agree with Brock, by the way. The Awlgrip Application Guide is technically correct, but asthetically vague about how to procede with aluminum prep and finishing. It provides 5 optional methods, but is less than specific as to why to choose one over another, and completely lacking in an explanation of which may be "better." I used the second method, which is for prepping aluminum when heavy fairing is involved. As Brock says, it is important to achieve a shiny, fresh surface before priming. Whether you do this through physical, chemical or a combination of the two can only be determined by your situation.

[Tim]

If your mast is 40 years old, most of the anodized coating is probably long gone. When I painted my mast last fall (despite the ultimate dismal failure thanks to the lateness of season and severeness of dew and frost), I only slightly cut the surface of the old aluminum with sandpaper, since I chose the more aggressive chemical-all-in-one-day application process.

Click here to read about the process (which works well, even if the frost ruins the end result).

If you're going the heavier grinding, 36-grit route, it's generally very clear when you have sanded enough. You are looking for clean, bright metal, and as soon as you acheive that it's sufficient. If there is indeed any old coating still on the mast, you'll break through it easily, but won't acheive the bright metal appearance until you do remove the old material.

The key is that you are definitely looking to do more than just break the surface. Grinding to the clean, bright surface is important to ensure that other coatings and contaminants are removed. Also heed the directions when they say not to use rags on the 36-gritted surface, as it can leave threads behind that will wick moisture into the paint later, possibly causing premature failure.

The decision how to proceed is generally made substantially for you depending on your choice of application. For brush/roller jobs, you cannot use the all-in-one-day method, as not only is the 30-Y-94 primer not made for brushing, but you cannot apply topcoats by brush on top given the limited cure time window.

The Awlgrip manual definitely takes a few reads to properly decipher the aluminum section. Hopefully my and others' experiences posted here will make the process more clear.
For brush/roller jobs, choose one of the other preparation methods, probably the 36 grit route used by Brock.

[George ( C&C 40 )]

Hi Guys,

I'm not sure if I mentioned it or not in any of my previous posts. I sanded the mast, boom, and spreaders down to bare bright metal before I started the painting process. I think I used 48 grit on the mast and 80 grit on the boom and spreaders. I didn't have any dings or scratches to contend with though. Also, when doing a brush job on aluminum I would use the gray 545 primer. I seem to remember somewhere in all that U.S. Paint literature it says that you should only use the gray with aluminum.

George

[Commanderpete]

This discussion is really helping. Confidence grows.

When I was researching the project, I decided not to use the Awlgrip products because I (mistakenly) thought Awlgrip had to be sprayed.

I also came across this article

http://www.anzam.com/howto_index_005.htm

So far I've removed the hardware (mostly), cleaned the mast and filled unnecessary holes with JB Weld.

Plan is to:

1) Sand mast

2) Etch/clean with PPG 533 (like Alumiprep)

3) Coat with PPG 503 Aluminum Conditioner (like Alodine)

4) Prime with Interlux Epoxy Primer

5) Top coats with Interlux 2-part Perfection

I'll do steps 1-4 in one day.

Going to roll & tip the paint, although I'm not sure if the mast is big enough for even a small roller.

Anyway, that's the plan. Hope I haven't forgotton something.

[dasein668]

Going to roll & tip the paint, although I'm not sure if the mast is big enough for even a small roller.

You don't have to roll. You can get a decent finish with just a brush too.

[George ( C&C 40 )]

Hi Guys,

You can certainly use just a brush. Just make sure you keep the paint thin enough that it doesn't sag. That was the one issue I had when doing the final coat on my mast.

George