Clearcoat over polished aluminium?

Loman · #1 01-20-2009, 06:11 AM

This may be a stupid question (from a newbie) but can you put a clear coat over polished aluminium?

I was thinking of a polished look, but the cowling and FG tips have to be painted anyway so a design incorporating solid colour on these and extending over parts of the rest of the plane is required. Why not use a base coat and clear coat system and extend the clearcoat over the polished parts as well?

Is there a problem with adhesion, or a chemical reaction with the aluminium, or perhaps the polishing compounds can't be removed sufficiently to give a clean AND shiny surface for the clear coat?

As a related question, for those who have polished planes, how do you clean at the edges of the painted/polished surfaces without damaging or contaminating the other side of the line?

Loman
RV9, Wings. Fuse on order

Kahuna · #2 01-20-2009, 06:31 AM

Clear coat will have adhesion issues to both polished bare aluminum, as well as out coated skins. Thermal expansion as well as flexing will cause cracking and flaking. Clear coats are hard and need lots of adhesion.

If you were just coating an aluminum something a ruther to sit on your mantel at home, you would be fine.

Best

Righty · #3 01-20-2009, 11:18 AM

Loman,

You might check this stuff out. It's a clear ceramic coating.

http://www.rfs-services.net/coatings.htm

I was considering the polished look myself and came across this. I was told that applying to an already polished surface is actually the preferred method for this particular coating. Another claim is that this creates a very slick surface that "nothing" will stick to once it is cured (e.g. bugs). I wonder if this would affect things like drag and stall speed?

Sounds like amazing stuff, but I have no experience to confirm these claims, just food for thought.

Pirkka · #4 01-21-2009, 01:47 AM

Ceramic coating seems to be something that might work. I did some web search and found out that there are actually quite many manufacturers for the stuff so it seems there are many possibilities. Also that this is actually not anything new but discovered already some time ago (~5 years). Also it seems to be used but as price is somewhat high it's used only on "better products".

Some brands and users for their products in car industry:

PPG: Mercedes Benz, BMW
DuPoint: Mercedes Benz,
BASF: Maybach, Rolls-Royce, Mercedes Benz
Unknown brand: Ferrari

It seems that some are not talking too much about ceramic but rather nano technology . Auto forums seems to have much more info about his so for further info that might be the place.

Some general stuff about these coatings (Jan 2006):
http://www.carwashmag.com/pdf/jan_2006/german.cfm

PPG Ceramiclear Clearcoat:
http://corporateportal.ppg.com/NA/Co...160_ClearCoat/

DuPoint Ceramic Coatings:
http://www2.dupont.com/Directories/e..._Coatings.html

I couldn't find proper link to BASF procuct.

Hwood · #5 01-21-2009, 09:01 AM

Bugs will stick to anything, regardless on how slick it is!

Righty · #6 01-21-2009, 04:35 PM

...the degree of difficulty of removal of smashed bugs can vary widely depending on the surface condition.

Loman · #7 01-21-2009, 04:58 PM

Thanks guys. These responses are great. Now I have a whole new line of research to follow - part of the fun.

I am still interested to know about cleaning on the paint/polish boundary though. That seems to me to be a problem area, at least as far as any cleaning compound goes, and every polished plane has to have these boundaries where metal meets fibreglass, so someone must have come across it.

Comments anyone?

szicree · #8 01-21-2009, 05:44 PM

Wouldn't it be cool if somebody could figure a way to put a matte color anodized finished on the skins?

mannanj · #9 01-21-2009, 06:11 PM

Quote:

Originally Posted by Loman

This may be a stupid question (from a newbie) but can you put a clear coat over polished aluminium?

I was thinking of a polished look, but the cowling and FG tips have to be painted anyway so a design incorporating solid colour on these and extending over parts of the rest of the plane is required. Why not use a base coat and clear coat system and extend the clearcoat over the polished parts as well?

Is there a problem with adhesion, or a chemical reaction with the aluminium, or perhaps the polishing compounds can't be removed sufficiently to give a clean AND shiny surface for the clear coat?

As a related question, for those who have polished planes, how do you clean at the edges of the painted/polished surfaces without damaging or contaminating the other side of the line?

Loman
RV9, Wings. Fuse on order

Loman:

Go to the Nuvite Polish Web Site. I don't have that address handy but you can Google it. They don't recommend any coating over their polish. Read through their info thoroughly.

Polishing is initially a pain in the ***, but it gets easier with each polish. After a couple of times polishing, you can essentially go for a year between polishing and it won't take longer than waxing.

Initially you will have to mask off the bare metal/paint boundaries when you "compound" the aluminum. Later with the "S" grade you don't have to do that, just be careful that you don't dwell to long on the paint/decals.

Hope this helps. To each his own and this is just my two cents worth!

InsideOut · #10 01-21-2009, 10:53 PM

Don't do it!

Airstream trailers have been clear coated since 1964 and not one of them will last very long. The factory now installs a mill finish aluminum with a factory applied clear-coat and I've seen them fail in 2 years. It has to do with the coefficient of expansion of the two materials vs. the adhesion between them. Failed clear coat looks way worse than oxidized 2024 alclad aluminum. I would bite the bullet and do a full polish with Nuvite:

http://www.perfectpolish.com/

Other than time, you won't regret it.