What paint do you recommend over Alumetron for painting my T Top?
E. Greg Gilbert asked:
Thank you for the information on the Alumetron process for painting my aluminum T Top, that I will follow. The pitting on the rails is minimal but the whitish oxidation is noticeable. I will send before, during, and after pictures. Will be starting on the project beginning of November.
Also, Can you recommend a paint? Looking at white, flat or glossy, and most suggest a two part type.
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I look forward to seeing pictures of your progress.
By using Alumetron as the first layer (4 thin coats) It’s providing the actual protection of the aluminum. It bonds chemically to the aluminum and that’s why it’s so durable. Other coatings, even the 2 part systems are prone to cracking, peeling and delamination. That’s why most people stop at the clear coat, providing that they get the aluminum appearance restored to the mill finish or over etched to look like anodized aluminum. Beyond the first protective coats of Alumetron, everything else is cosmetic.
In your case, you’re after a white painted appearance. The paint type that I would recommend is a water based acrylic. It will be most compatible with the Alumetron.. The number of coats that you apply will be dependent on the viscosity of the paint and the application. Remember, all that you want is a color coat, and thinner is better. One coat is better than two, two better than three etc. Thinner coats will give the part more flexibility and durability. You may require more coats to get an even color, depending if you spray or brush.
Alumetron is very thin while the paint, containing pigments and fillers, is far more viscous and will give you a higher build so just use enough to give you the color. Water based acrylic paints are not all that durable, that’s why the Alumetron overcoat is recommended. It will give you the added durability. Also, Alumetron requires a wipe on application, whereas you may get a smoother finish from the paint by spraying. Just be careful as spraying typically results in a thicker coat. A lot will depend on your skill level. It’s difficult to screw up the Alumetron finish, unless you overwork it or try to apply it to a contaminated surface. Applying the paint is a little trickier.
The other important thing to remember is that you’re dealing with water based systems, which have a lot of advantages and are more environment friendly. The down side is that they take longer to cure. You need to allow enough time for the water (used as the solvent) to completely evaporate in order for the coating to polymerize and cure. With Alumetron this is a minimum of 96 hours or 4 days but can be longer depending on the ambient temperature and humidity. If it’s cool or damp allow more time.
The reason that others are recommending a 2 part system is that they are thinking about the older epoxy or polyester solvent based systems, in which case the addition of the cross linking chemical just prior to application causes a chemical reaction which can be more durable and give a faster reaction and curing time than a simple air borne cure. The better systems are quite toxic and can only be applied by certified professionals. Also these systems require etching, chromate primers and in some cases heat or baking. Much more expensive, involved and harmful to the environment. Even so, these coating are prone to peeling, blistering and delamination as they do not form a bond with the aluminum, but just sit on top of the surface. Epoxies are very durable but are sensitive to UV degradation and must be protected by paint or at least be pigmented and they’re harder and more brittle therefore subject to cracking, especially to substrates that flex such as on boats.
It’s quite difficult to get anything to bond to aluminum, that’s why Alumetron is so unique. It creates a chemical bond, so even if you get a scratch or breach in the coating, the damage remains localized and can be retouched instead of the coating lifting and peeling. Alumetron is even suitable for underwater applications, whereas other coatings have limitations.
If you’re in salt water or require more durability, such as where people will be grabbing or holding on with their hands, you can overcoat these areas with VS721, low surface energy coating. Salt can’t stick to the VS721 so clean up is much easier. Just rinse clean with water. No washing with salt remover required. VS721 will also give you much more durability in high traffic areas and reduce buildup of skin oils and grime.
Thanks for your question,