How can I tell if there’s still a clear coat?

[ChelleZ]

Hi! I’m restoring a 1975 international overlander, and before I get to work on the exterior, I’m trying to figure out if there’s still a clear coat. Is there an easy way to tell?

[Bubba L]

A lot of people just squirt a small dab of toothpaste on a paper towel and rub the aluminum in a small circle. If it turns black, there’s no clear coat. If it doesn’t, there’s still a protective film. I’m sure there’s other ways to check. Good luck

[ChelleZ]

Thanks Bubba- do you know what ingredient in toothpaste we are looking for to cause the reaction? just thinking since there might be many different kinds of toothpaste out there.

[dznf0g]

Originally Posted by ChelleZ

Thanks Bubba- do you know what ingredient in toothpaste we are looking for to cause the reaction? just thinking since there might be many different kinds of toothpaste out there.

I have used paste....white with the micro gritty texture.

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[Bubba L]

It’s not a chemical reaction but the grit in the paste that removes the aluminum oxidation on the Alclad that is black. Right Rich?

[dznf0g]

Originally Posted by Bubba L

It’s not a chemical reaction but the grit in the paste that removes the aluminum oxidation on the Alclad that is black. Right Rich?

Yes, auto cleaner/wax works too, but then you have a clean shiny spot. The idea is transfer of oxidation. Any clearcoat oxidation is colorless. Aluminum oxidation is blackish.

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[JCWDCW]

Yes it is the grit in toothpaste actually 350 mesh ‘sand’
The other ingredients are hair shampoo base that makes the foam, ( sodium lauryl sulphate) some things to make it thick and smooth and colour and flavour
KCW

[InsideOut]

Yep, testing with a tiny dab of toothpate on your finger will tell you. Make sure you clean off the area you are testing with water first.

The fact is, if your trailer is a 1975, it probably has clearcoat in different phases of failure on it unless someone before you stripped it or it was always stored indoors out of the elements. So some areas - usually the top - won't have good clearcoat and other areas more protected from the sun & weather like the bottom sides will have more clearcoat left. The "peeling sunburn" look you see in vintage Airstreams is due to the clearcoat failing over time and the exposed aluminum oxidizing more where the clearcoat has failed first. Older failures = more oxidation, which makes it look grayer.

Are you planning on polishing your trailer? If so, you will want to make sure all the clearcoat is removed before starting to polish. We've polished two trailers - one 19' and another 22' - our '64 19-footer had failing clearcoat which needed to be stripped first, our '56 22-footer did not. With clearcoat, even with different stages of failure you have the extra step of stripping, but the areas that are still protected are easier to polish. Whereas without ever having clearcoat, there is a lot more polishing to remove the oxidation...either way, it's a lot of work!

A 26 ft Overlander is a lot to polish, but they sure look look great when done! Good luck!

Shari