HMG Paints

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Michael Rogers Michael Rogers
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HMG Paints

I came across information about these marine paints by 'accident', as one sometimes does when googling something else.

Does anyone have experience of using them? In particular of -

  - the claimed very quick dry/cure time of their two-pot topcoats

  - Microshield/Aluma-Protect 102 Topcoat (a thin, clear and allegedly very tough coating for aluminium) as a possible alternative to anodising. My interest is aluminium tubing for junk sail battens: the tubes aren't expensive, having them anodised is!
Jeremy Jeremy
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Re: HMG Paints

Aluminium is a bugger to paint successfully.  I've built a few aircraft with aluminium parts and have tried a few ways of getting paint to stick reliably.  Self etching primer is the popular choice (essentially a two-pack zinc chromate wash primer with phosphoric acid as an etching agent).  This is OK, but not very abrasion resistant.  It makes a good primer coat for tougher finishes though, and is compatible with most types of paint.

Hard anodising is without a doubt the best finish, but is hard to do at home for anything other than small stuff (small parts are easy to anodise at home, all you need is a battery charger, some diluted battery acid, a plastic container and a bit of lead sheet).

The best treatment I've found, in terms of prepping an aluminium surface for a good surface coating, is Alodine.  It's a fairly easy process to use and can be applied to big parts in a DIY environment.  It's also not overly expensive.

Finally, there is the really cheapskate process, using Vim or Ajax (if you can find it!) and phosphoric acid (available as "rust converter" from car repair/paintshop  places).  Give the aluminium a good scrub with Vim/Ajax and a moist Scotchbrite pad, rinse and then immediately wipe the surface with phosphoric acid (which is fairly harmless, it's the flavouring in Coke).  The result will be a very matt looking surface that is finely etched and ready for any sort of primer and topcoat.
Michael Rogers Michael Rogers
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Re: HMG Paints

Thanks, Jeremy. Having done some further research, based on your reply, and knowing your way round relevant suppliers as I know you do, can you point me to possible sources of 'Clear Alodine', otherwise apparently known as MIL C 5541?

Googling this turns out to be hopeless, as it only seems to turn up websites of electronic parts suppliers who sell hundreds of components treated with MIL C 5541, and not a single supplier of the actual brew!
Incidentally, as I am sure you will correctly assume, I don't need or want gallon cans of the stuff. A pint or half litre would do just fine.

Thanks again      Michael
Jeremy Jeremy
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Re: HMG Paints

I last bought some from Aircraft Spruce and Speciality in the US, but I see that they now sell it in small cans from their European online store, here: http://www.aircraftspruce.eu/index.php?q=alodine&x=9&y=3

You might want to try your local Henkel coatings supplier, too, as the stuff is made by Henkel, I believe.

There are quite a few guides on the web to using Alodine, mainly on home aircraft building web sites, if you need tips on using it.
Michael Rogers Michael Rogers
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Re: HMG Paints

Thanks again, Jeremy. I've ordered some. Shipping from Germany bumps the cost up a bit, but it will still work out much cheaper than anodising. It's not as though junk sail battens have a rough life abrasion-wise on the whole, except at certain points (eg between mast and batten) where soft PVC pipe can be slippped over to form fendering anyway. Also the makers of Seacoat suggested to me that a coat or two would help over the Alodine treatment: that is to say, I asked them and they agreed. The result will be a bit shiny, but I can wear sun glasses prn*.

Your knowing where to look, Jeremy, is invaluable where boat-building and aircraft-building-and-fettling share common ground, especially as the flying bits (websites and the like) are even more esoteric than the boating bits!

(*A useful (if old fashioned) medical abbrev, meaning 'as or when necessary'. Short for mediaeval dog-(ie bad) Latin, 'pro re nata'. There's a piece of useless information for you!)