Etching tiles with multi-color (painted layers)

I keep having to up the anti. First it was white tiles with one color or paint. Then white tile with two colors of paint. Now I am trying white tile with FOUR colors of paint and some with three. I will be laying down a combination of yellow, orange, red, and black. Also yellow, green, and black.
The idea is to burn through the black to show the color under it. Also to burn through that color to reveal the color under that and so on until you get down to the white tile. I wanted to try doing the sun tile again with the yellow, orange, red, and black paint. That way as I burned deeper into the paint, it would look like the hotter parts of the sun. There were two major mistakes I made with this project. The first was to not wait long enough between layers of paint.
This caused the next layers to interact with the layer under it to make it look cracked. The yellow also spat out of the cat at first. I had not had this happen before. I knew it could be an issue and that is why you should always do a quick test spray from the can to insure a fine mist before you spit paint onto your target. In addition to not waiting long enough between layers was to put a NON-WATER BASED clear finish on the tiles.
This also reacts with the paint and bubbles it up. Kind of like putting lacquer thinner on paint to remove it. The textures look is kind of cool but not what I was going for.