I do a lot of aluminum sculptures and am always looking for a better clear coating for aluminum. I am a big fan of SculptNouveau.com and have bought a lot of patina chemicals, coating, dyes, etc. from them over the years. Debbie Young usually drop in a free sample of something new to try. Ron Young’s has numerous videos for sale and on You-Tube that are quite excellent.
New Clear Coating from Sculpt Nouveau
Sculpt Nouveau has just come out with a couple of new clear coatings. Smart Coat is a water-thin urethane/resin clear coat with a zero VOC rating that dries to a satin finish. You can brush it or spray it – don’t roll it, they say. I am accustomed to clear coats darkening patinas, but this one does not darken a patina at all, which could be good or bad. Sometimes a patina will look crusty white before lacquering then, after lacquering, dry to a lovely transparent color. This works with a solvent-based clear coat – not with Smart Coat. On a patina, it dried to a rather unpleasant-looking satin. However, on aluminum, it looks glossy – brighter and shinier than the sanded aluminum. Very nice.
Smart Coat is also available in transparent tints called Smart Stains – a very nice option. Sometimes you need a little transparent color to enhance or modify a patina after it has been lacquered. This makes it easy.
SN has also come out with another clear coating called Clear Guard. This is a solvent-based air drying lacquer. SN claims that it has virtually non-existent orange peel, and that seems to be true. It is available as satin or matte. I tried satin. On a patina, it does darken the patina nicely, and is very satiny. On aluminum, it also appears shinier than the metal.
Clear Coating Tests
The good news is that both of these SN clear coatings adhere extremely well to aluminum. Apparently, one can even be used on top of the other, for added protection.
24 hour cure: Fingernail scratch test – both perfect; cross-hatch with scotch tape – 100% adhesion; 120 degree bends – 100% adhesion.
This is quite remarkable. Incralac clear coating sticks poorly to aluminum. Krylon clear coating sticks better, but can be scratched off with a diligent fingernail. Krylon clear coating also gets water spots from prolonged contact with snow on an outside sculpture – not good. Krylon Triple Thick clear coating is very rigid and fails the bend tests though I like it over patinas – it really soaks in and wets them out.
I prefer to put a clear coating on aluminum because I like to scratch up the surface of an aluminum sculpture with a sanding disc, grinding wheel or 3M pad. But those scratched areas are recessed and then can pick up dirt. Clear coating keeps the dirt out. Also, a clear coat keeps fingerprints off, makes the sculpture more easy to clean with detergent and water, and makes it more pleasing to the touch. Finally, uncoated aluminum looks very bright and platinumy at first, but over time dulls to a medium light gray as the aluminum oxide builds up.
Latex paint and acrylic paints are notorious for not sticking well to aluminum – an aggressive fingernail can scrape them off. Neither Smart Coat or Clear Guard improve this, sad to say. However, oil paints and oil-based paints adhere to aluminum very well. Aluminum is actually a catalyst for oil-based paints and will speed up the drying time somewhat.
I will be testing these clear coatings further on copper, stainless steel and bronze soon.