Have you ever tried to use masking tape for its intended purpose only to discover that, no matter how carefully you apply the tape, paint bleeds under it, ruining your efforts?
Making clean paint lines between two colors doesn't have to require a steady hand or special equipment. This technique is very simple and requires only paint, brushes and masking tape. This time, however, you will be controlling the bleeding paint and using it to create crisp lines that precisely follow the edge of the tape.
Step 1: First Color
Lay down the first color, extending past the area where the line will be. If you are using two layers per color, paint both layers.
Step 2: Taping
Once the paint is dry, place your masking tape. In this case, the bottom of the masking tape marks the location where the edge between the two colors will appear.
Step 3: Bleed Line
Using the same color, paint along the tape edge. This seems strange but, there will always be some bleeding under the tape. By deliberately painting against the tape, you seal the edge with the first color, allowing it to bleed under the edge, so the second color can't do it. The edge of the tape becomes the edge of your line.
Make sure the lower edge of the paint feathers softly away so you won't see a thick edge of paint later on.
Step 4: Second Color
When the bleed-under layer has dried, paint the second color. Make sure your paint overlaps the location of the tape line.
Step 5: The Reveal
Remove the tape by pulling it at a 90 degree angle. Do this when the paint is wet, if possible.
Tah-dah! Crisp, clean paint lines!
(I hate adding a caveat but it seems warranted here: I haven't had any problems with the line when removing the tape after the second color has dried BUT other people I know have. It has to do with paint setting up and binding to itself. So, if you cannot pull the tape while it is still wet or at least soon after it dries, you might consider using a craft knife and a straight edge to score the line before pulling the tape.)