I have heard of Alclad II and others similar including the Motolow brand pens and spray paint.  I use Spaztix. There's a slight learning curve with it but it's not steep.  Most people use gloss black as a base but that's only because they are spraying it over another surface and want the colour to be consistent - not splotchy. I have painted it over white, red, and black, and even gray. It brings out more depth in darker colours but it really makes no truly profound difference in the overall effect. I had Alclad II that I sold and never used. After watch a YouTube video I've seen a comparison between the two and it's night and day. It's not as durable as Spazix and cannot be clear coated over without dulling. Also it doesn't have the same depth no matter what colour your undercoat is.  I see that this is brighter in white than it black meaning that it is slightly lighter so if you're looking for a more polished aluminum look - use white. If you're going for a more chrome look with a slightly darker hue then go with black for the undercoat.  I bought mine from the local hobby shop for $12.00 a year ago.  I got the spray cans just so I could experiment without breaking out my airbrush(es). I have Spaztix in the airbrush bottle too but it has to be poured out into an airbrush and that takes more time and effort than I want to put in when I use it.

Here are two links that you might find useful:

 https://www.hobbyrecreationproducts.com/products/szx10009-ultimate-mirror-chrome-aerosol

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