I paint a lot of buildings.
Therefore I paint a lot of windows.
And there's a trick to that.
I use a masking fluid to help me paint all those window pane lines. It's similar to using rubber cement, but this stuff can be applied delicately with a tiny brush to create very fine lines. Rubber cement doesn't offer the artist as much control and is normally used to mask very large areas of the paper.
Both rubber cement and Miskit do a very important job. They repel water and watercolor paint, keeping the white of the paper white! The white of the paper is a very precious thing in watercolor painting because there is no white paint!
Pretty much for all the windows I paint, it goes down like this:
1. I paint the pane lines with a masking fluid.
2. I paint the windows.
3. I remove the masking fluid with a rubber cement pick up (an eraser-looking object that's made specifically for this purpose) revealing the still white paper underneath.
4. I make any necessary touch-ups and that's it! Perfectly lined windows. I use the term "perfectly" very loosely.
Miskit is useful for a few other things too, like putting stripes on a flag or lettering signs in a painting. I'm definitely a fan!