'Blisters undeerneath the paint on an aluminum sheeted vehicle can have more than one origin.
If the paint is a multi-part member of the epoxy family such as Imron or Coronado coatings then even the slightest particle of dust on the metal at the moment it was painted will eventually turn into either a blister or filament type degradation under the paint. This is common on aluminum skinned aircraft. Even the finest paint rooms with positive airflow and filtration do have small dust problems from time to time. The industry suppresses that fact and just gets the production done! A certain percentage of all vehicles painted that way will have issuers in a few years.
The only long term cure is to very carefully sand through the existing paint in an area larger than the damage by at least two inches. Carefully fine sand down to the shiney metal [no imperfections at all] and then use a solvent like MEK or similar to wipe the area and allow it to dry immediately before re-priming with corolar or similar high end primer. Do not sand the corolar. You either get it right or remove it and do it again! After the primer is dry respray with the original color.
Of course if your rig is older then the original color will not match because of sun fade so this is a job for a high end paint shop. Working with two part paints and epoxy primers is a job for a pro or you will learn the very hard way!!! Some of the substances are controlled and you are required by law to be trained on their use and application and to have proper equipment. Pretty much anything you could buy over the counter for the layman to use will not do the job well or for long.
Slim
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Got good friends and loving family? You are wealthy.
1993 Safari Continental 37, Cummings/Allison
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