Mast Painting

The "re-birth" of Stars & Stripes continues! Thanks for the info on removing rivets, worked like a charm. I now am looking to repaint my mast and boom. They are powder coat black with no damage at all except for allot of scratches. I want them to be flat black again. Any ideas on this area would be most welcome. Next...the hulls! I'll start posting some pictures so everyone can see the transfomation of my girl. I have been really impressed at the tightness of the hobie cat community and everyone has been wonderful, the support has been awesome. Have a Hobie Day!!

Thanks everyone!

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Sean Wheeler
[email protected]
http://hobie-14.ning.com/profile/SeanWheeler
'83 Hobie 14 Turbo "Rio"
Blue Hawaii Sail #40954

It isn't powder coating - it's black anodizing.

To get paint to stick (permanently) to the aluminum, you need to acid etch it and use a conversion coating.

Or, you could just go cheap and use rattle-can epoxy appliance paint. It'll look good - for a while.

Oops! I'm just about to re-paint my mast, rudder castings, tillers, cross bar and beams with a blue/black 2-pack polyurethane. Is this not a good move?

Probably not.

It'll look great at first.

Then it'll start to chip. And flake because it doesn't have a good chemical bond with the aluminum.

After a year or so, it'll look worse than ever. Then what do you do? Sand it all off and start over?

The Penetrol works great at making the non-scatched black anodizing look like new.

In building construction, there is an anodizing solution that repairs scratches in the black anodized aluminum window frames and moldings. It is an anodizing solution. I can't remember if there was a cleaner or sealer that came with it. I just remember the small fingernail polish sized bottle with brush and clear liquid would turn the bare aluminum into black to match. It has been 20 years since I used it, but may be worth looking into. I cannot seem to find it when I search the web, but should be known by window suppliers....

Thanks very much for your prompt and helpful responses - much appreciated

viewtopic.php?f=9&t=16218&p=84849&hilit=anodize#p84849

I haven't checked to see if the guy on Ebay still has any alodine, but if not you can google it or buy it here http://www.chemical-supermarket.com/pro ... ductid=364
I see the price has gone up on the 1132 pens here 25% since I last looked

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TC

I have a client who works with Aluminium all day, as in Shop Fronts & Glazing. (He is also a boater, and has won awards for his restored runabouts, those shiny, narrow, mahogany power boats. I'll get him sailing on the H18SX this summer, and do my best to 'convert' him.)

In the meantime, here is what he said about Alodine......

"This is usually used on bare uncoated cast aluminium parts, your mast is an Aluminium extrusion and most likely has been anodized not suitable for any kind of painting. I would not recommend using this on your mast. You will be better off to try buffing the mast with a cleaner."

Only four months until we can sail again......

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2015 H16, with spin,
SOLD 1989 Hobie SX18 Sail # 1947 "In Theory..."
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'

John, I think your client is mostly correct, but wrong in his conclusion. I'm not an expert either, but let me share with you some real world applications and you can make your own educated decision.

This is an Atlas V booster. http://en.wikipedia.org/wiki/File:Atlas ... raised.jpg The orange brown section you see is alodined aluminum. The engines are from Russia...but don't get me started...

Here is Pad 41 where the Atlas V launches from. The Atlas may sit on the pad or it's nearby service structure for months at a time. In the background you can see the Atlantic ocean, and the reason for the alodine. http://commons.wikimedia.org/wiki/File: ... Pad_41.jpg

Here are some comments and opinions from an industial rag concerning Alodine http://www.finishing.com/124/66.shtml

This is an exerpt from the manufacturers description.

Detailed Product Description:
Alodine® 1201, a registered trademark of Henkel Surface Technologies, is a chemical
treatment process for aluminum used to provide corrosion protection and as a surface
preparation for paint and adhesives. Sometimes called “aluminum passivation,” it
contains hexavalent chromium and is intended to provide corrosion prevention even
when left unpainted.

Specification & Certifications:
Alodine 1200 methods and properties are defined by Mil-C-5541-F (Now AMS-C-5541)
and AMS-A-2473.

Application Notes:
The best results are achieved on wrought alloys (machined billet aluminum alloys).
Good results can also be achieved on type 356 aluminum castings. Type 380 die
casting alloys do not alodine well, however. It should also be noted that the
chemical film is fragile immediately after processing and a 24-hour waiting time
before handling the parts is preferable.

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TC

Sorry for the double posting, but for some reason I couldn't finish my above post as everything was jumping around.

Anyway...what I can't answer is what type of aluminum the masts are extruded from. According to the manufacturer, some types do indeed react better than others. Maybe Matt can chime in here and educate all of us as to what type of alloy Hobie uses, if it's not a trade secret. He might even offer an opinion on alodine!! I know that I'd like to know.

At any rate, your client is correct, paint doesn't stick to hard coat anodized surfaces very well. However, alodine, while no where near as good as hard coat anodize, is a chemical conversion that's about as good as you're going to get for repair purposes.

I've never had any luck buffing out hard coat, maybe others have, but it's still not going to buy you any corrosion protection...it may look pretty though.

Here's the deal. If you properly prepare the surface, alodine is better than paint, but not as good as hard coat. You can topcoat alodine with a good quality paint, but you'd need to scotch brite the surrounding hardcoat to have any hope of having the paint stick to it.

So the question is, for $16 a pint http://www.chemical-supermarket.com/pro ... ductid=364 why wouldn't you want to use alodine for scratch repair?? JMHO The real difference between this and the $100 alodine pens is convenience. The pens you wipe on and walk away, the liquid you need to agitate and keep the surface wet for a short period of time.

I also use Penetrol. The only bad thing about it is it doesn't last, and needs to be re-applied.

As far as powder coating...don't waste your time.

Again, all the above is just my opinion.

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TC

Krylon (black) Primer

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Happy Sailing,

David

The aluminum extrusions used in Hobie Cats (and almost all sailboats for that matter) are made from 6061 alloy, then they have the T6 tempering process applied. Thus the "6061 T6" label.

Bare aluminum oxidizes very quickly upon exposure to air, forming a barrier against further corrosion.

In the anodizing process, the bare aluminum is first cleaned with detergent to remove any oils or contaminants, then chemically etched to remove the thin layer of oxide. Then comes desmutting: Rinsing in an acidic solution removes unwanted surface alloy constituent particles not removed by the etching process.

Anodizing: Aluminum is immersed in a tank containing an electrolyte having a 15% sulfuric acid concentration. Electric current is passed through the electrolyte and the aluminum is made the anode in this electrolytic cell; the tank is the cathode. Voltage applied across the anode and cathode causes negatively charged anions to migrate to the anode where the oxygen in the anions combines with the aluminum to form aluminum oxide (Al2O3). View our anodizing video.

Coloring: Anodic films are well suited to a variety of coloring methods including absorptive dyeing, both organic and inorganic dyestuffs, and electrolytic coloring.

Sealing: In all the anodizing process, the proper sealing of the porous oxide coating is absolutely essential to the satisfactory performance of the coating. The pores must be rendered nonabsorbent to provide maximum resistance to corrosion and stains. This is accomplished through a hydrothermal treatment in proprietary chemical baths or by capping the pores via the precipitation of metal salts in the pore openings.

Alodine is a chromate conversion that is more cost effective than anodizing, but not nearly as durable. It's OK for scratch repair, but it's not suitable for bringing back the finish on faded anodizing, because it must be applied to bare (chemically etched) aluminum.

It's also flammable and hexavalent chromium is nasty stuff. The Erin Brokovich story was about a town whose groundwater was contaminated with the stuff.

That pretty much sums it up...

You also should wear gloves, and avoid skin contact while applying it as it is a known carcinogen....but what isn't these days? Like any paint or motor oil, don't dump the waste down the drain or on the ground either. Not sure about it being flamable, as you can purchase it as a dry powder that you mix with de-ionized water. I do know they re working on a non-hexavalent chromium formula, but don't know if it's been released yet.

Appreciate the info on the alloy type.

Thanks.

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TC