Blistering paint on freeboard of Aluminium hull looking for a remedy/solution.

[minaret]

Originally Posted by groundtackle

Posts and pictures of the dodger will be coming soon on the "build a hard dodge" thread. First coat of primer (corspec135 zinc chromate primer) goes on tomorrow afternoon after a final scratch and acid etch in the morning.
Nick

Follow ASTM guidelines for coating alu. This requires applying first coating within 45 minutes of abrasion. This is challenging on large surfaces. I sand blast for abrasion, blow with DRY multiply filtered air, no wipe at all even solvents (unless it's T0115), apply primer immediately after blasting bright. New primer systems in the US make alumprep/aludine etc obsolete, no longer required or recommended. And the key factor of application as per ASTM guideline which I see most often ignored resulting in failure; the substrate must be at least ten degrees F above current dew point. Read this as DON"T PAINT COLD ALU, as it will condense moisture out of the air in less than the proscribed 45 min if it is less than ten degrees F above dew point. Can't overstate the importance of this factor; I have coated and recoated/refaired a large number of alu yachts. It must be warm to the touch when you apply the first coat if you don't want it to fail. This means heat the inside of the boat while blasting and coating outside if possible. Do NOT use an exterior heat source such as propane or diesel fired furnace; this will introduce moisture or soot/exhaust contamination. Just my 2c.

[minaret]

Here ya go, Wash Primer CF, chromate-free.



http://www.awlgrip.com/products/prim...primer-cf.aspx


Follow the guidelines.


http://www.awlgrip.com/LiteratureCen...n_guidance.pdf




This is the new flavor, no etch required, chromate-free. And yes, you can get it in a rattle can! This is an awesome feature. I generally wash prime, then apply a ton of 545 by chemical bond, as if you blow through you need to spot prime following the same ASTM guidelines. That's where a rattle can is sweet. I know some pro's who blow on high build over the 545 by chem bond to prevent burn through, but I don't like to use high build at all.

[David M]

I have been running an aluminum hull for over 30 years.

There is no cure for the blistering of paint on aluminum.

10 years is a pretty good interval for needing another paint job.

I know it is sexy to say that if something is used on aircraft, therefore, it must be good. The aluminum on aircraft are not exposed to salt like boats are. Just because some coating system is used on aircraft does not mean it is going to work on a boat.

If aircraft were hosed down with salt water on a daily basis they would not be airworthy in a few months...if that.