With this Mondrian, I had to do it in many, many layers. The first layer I did was black, so the lines would be easy to do. I put green artists tape where I wanted the black lines to be, and covered it in white acrylic paint. After quite a number of layers to comletely cover the black paint. For the coloured squares, I just got the colour tat I wanted, and painted the square. I only did a few layers of the colours, and it was fine. After, I Took the tape off, and the black lines appeared. Somtimes there would be white in the black lines, or some coloured paint. I just got a fine brush and repaired it.