I got one of those chrome nail powder kits to try this out. I've been patching a set of old handlebars. Here are my notes:
-A sticky base is needed. The base is activated using a UV lamp. The base is a thick gel. It should be applied sparingly using a small paintbrush. The brush supplied with the bottle tends to put it on too thick. UV lamp for 90 seconds on the gel to activate. Do not touch the gel with your fingers. Gels can be clear or colored white or black. Experiment with the coloration to suit your needs.
-The powder is applied using the little pad/sticks supplied in the kit. It should be applied evenly to the gel. It will stick to the areas of gel activated by the lamp. It will tend not to stick anywhere else. The powder will tend to get on other areas, but will blow/brush away if no activated gel is there. Less powder is needed than you think at first. You need an area where there is no wind/minimal air movement. The powder likes to blow everywhere if given the chance.
-Excess powder should be gently brushed away with a clean, dry brush.
-A top coat of clear gel seals everything up. It's not the same gel as the foundation, but it is applied in a similar way. Again, it's pretty syrupy stuff. Apply with a paint brush sparingly. The brush supplied with the bottle will tend to put it on too thick.
-UV lamp 90 seconds on the top coat.
The result is a very hard finish. It looks better than most "chrome" paints look. There may be premium paints that look better, though paint tends to be kind of fragile. The finish is pretty durable, though somewhat brittle. It will crack-off using a utility knife blade (be careful) if you need to start over. Practice a little before starting on your project. It's very easy to get it on too thickly.
Keep your brush in acetone when not using - the gel will gum up the brush. Dry off the acetone when you go back to work with the brush.
It seems to work well in applications where you need to build-up layers. It's tricky if you're trying to patch it on very thinly. It tends to go on much thicker than the paper-thin layer of original chrome. But with some practice, a fair result can be had. It is not a substitute for good chrome plating, but it's an option if you need to do some patching and it's not worth paying for new chrome. It passes the 5-foot view test, but isn't a dead-on match up close.
It seems to work best where you have older chrome that is "wrinkled" a bit. It tends not to give the "glass smooth" type chrome look.