Paint blistering on entry door

[harry kew]

Have paint blistering on lower part of entry door
Anyone know what causes this ?
How it can be repaired?
And how to prevent it from happening
Thank you

[Fred Brooks]

   Hi Harry,
 It is not blistering but appears to be electrolysis caused by dissimilar metals interacting with each other. The only fix is to sand it down to the metal and prep with zinc oxide to seal the metal. Then primer and paint. Hope this helps, Fred

[Eric Maclean]

Harry
The bad news is what you are looking at is corrosion as Fred mentioned the bad news is when you sand it you will find holes in the aluminum skin .
I've seen a couple of these including the door on my coach it is usually caused by water getting inside the door ( a leak in the upper door or in my case the front cap seam above the door )
Once the water gets inside the door the wood behind the outter aluminum skin holds the water keeping the aluminum skin wet causing the corrosion.
To fix this first you have to find and stop the leak then either dismantle the door and replace the inner ply wood and new aluminum skin or as Fred was saying sand the corrosion off to clean aluminum patch any holes with a good epoxy ( west system) then an epoxy primer and paint.
Or just do what I did and get a nice piece of polished stainless steel cut and screw it to the bottom section of the door covering the effected area.
Good luck
Eric

[harry kew]

Thanks Fred and Eric
Good advice another project to put on my list

[Larry Fritz]

I did exactly what Harry did and: problem solved. Glued on a piece of polished SS after first smoothing the mounting surface area.

Larry fritz

[Jerry Carr]

Harry, blistering but appears to be electrolysis caused by dissimilar metals interacting with each other, over a 5-6 year I spent 4-5,000 trying to fix this issue. I was told by Steve the lead painter at Beaver Coach sale that the repairs we did would be temporary at best the issue is the electrolysis will continue. I would also suggest the SS plate or except the fact.