Recommend barrier between stainless steel spreader/boom brackets and mast?

[Reefmagnet]

Originally Posted by Rhapsody-NS27

Thanks, I've been looking at stripping down my mast. I've seen others who only sanded down the bad spots and even saw that recommended by others that if the paint is still adhered well on the mast, to leave it. But, I've been looking to strip it all down to bare metal.

While I've seen recommendations for Zinc Chromate primer, and I do have 3 rattle cans of it, I'm thinking to not use it. I'm looking at using Awlgrip products on this mast and they have a chromate-free primer, Wash Primer CF that I'm looking to use instead, after the alumiprep and alodine steps. The Wash Primer is still supposed to etch into the metal and provide a good base for the next layers of Primer/top coat.

Maybe the Wash Primer is something that could work for anyone not wanting to use zinc chromate.

Yes, my reasoning was where the old paint was super well adhered leave it there, but since I removed half the paint from the mast anyway (corrosion, plus a section of single pack recoat that would have fried up with the primer), I should have just kept going. I wasn't going for a showroom finish, but it ended up taking 2 days to touch up divots and reprime instead of just the extra half a day or so it would have taken to remove all the paint in the first place. Live and learn.

The epoxy primer that I used stated in the data sheet to mechanically sand the aluminium and paint within 6 hours. I did this but also used an aluminium cleaner containing hydroflouric acid to etch the metal immediately after sanding on the recommendation of the local paint supplier. I was happy enough with the final bare metal preparation, but I guess time will tell. I'm getting my boom done professionally by a friend of mine that runs an industrial sandblasting and painting business and he paints aluminium by sandblasting and prime immediately after with hi build epoxy primer. The "prime" objective is, I think, to prevent excess formation of oxide between preparation and painting.

[wrwakefield]

Originally Posted by Reefmagnet

Thanks guys, some good ideas. I already use TefGel, but there's just too much surface areas to apply the stuff for this application. It would send me broke(r) buying enough! I use it for all the rivets and screw holes. I'm soon to install 25 or so mast steps so that should see a fair bit required at least. I like the thin film idea. In fact I would (and will) use clear fruit juice container PET plastic made into gaskets for the smaller stuff. The boom and spreader brackets that I removed had what was either a slight amount of polyurethane or even a thin sheet of nitrile rubber installed. I'm not a fan of nitrile rubber for gaskets in this application because I've had problems with it "creeping" in the past on similar jobs and that would make me worry about having the rivets loosing tension. I like the idea of the plastic tape. Cheep and should work.

Rhapsody, I did a full repaint. First time ever. There's a couple of things I would do different if I did another one. The big one is that I would totally remove all the old paint. I spent more time trying to smooth over the divots left where I'd gone back to bare metal to remove oxide (which of course only reveal themselves after the primer has gone on) then I would have if I'd just taken all the paint off to start with. I used a 7" sander/polisher with a poly strip disk for most of this job. Paint was epoxy hi build primer with a polyurethane top coat.

Reefmagnet,

There is often confusion between Tef-Gel and Duralac I mentioned earlier. They are not intended for the same purpose, but accomplish the same end result. [electrolytic - dissimilar metals- corrosion prevention.]

Use Tef-Gel on threads and fasteners [including rivets.] Not as a barrier coat between larger mating surfaces... That is what the Duralac is for.

A small tube of Duralac will go a very long way, and you only have to tighten it once...

Cheers!

Bill

[sailjumanji]

I've used black electrical tape successfully for this. Just lay down rows of the tape, attach the item, and then trim off the excess.

[UNCIVILIZED]

I've read of some guys using pieces of plastic soda bottles as isolaters, as tough as the stuff is. Can't say as I've tried it though.