Painting With Masking Tape
Of all the discoveries I've made through my trial and error process in paintings, my very favorite is masking tape. It saves so much time and frustration and makes crisp looking lines. You can use plain hardware store masking tape to make edges of buildings, horizon lines, borders, stairs and anything else that requires a straight line. People always tell me they "can't even paint a straight line". Well neither can I, and with masking tape you don't need to.
In my portrait of a woman painting at an easel, there are many, many straight lines. I find furniture and perspective drawing pretty intimidating in general. Here's how I used masking tape to make things easier:
To paint the easel leg, I roughed in the area freehand with my brush. I started on the material of her dress in the background, going slightly over the edges. Next, I masked off the area with tape, pressing it down hard on the canvas. You might want to measure the distances and/or angles to make sure it's straight if you're not sure.
Next, I used white paint to paint the easel leg, overlapping the purple lines on the inside, and over onto the masking tape. I let it dry for a few minutes and then peeled it off:
In this case, I used white so I would have a transparent background for painting the wood grain of the easel leg, but if you're painting in a horizon or something opaque, you can just go ahead and paint on your mixed color.
If you don't get a clean line, you can let your paint dry completely (about 20-30 minutes for acrylic) and then mask the other side, following the same technique. In this example, I would put the tape onto the inside of the easel leg up to the edges, and paint the purple around it again. It wasn't necessary in this example, since the line came out clean enough that I could touch it up freehand.
Depending on what you're painting, you might not want a perfectly straight line, so you can use the masking tape more as a guide and touch it up to make a more natural line. You can see how I did this on the bottom of her palette and the bottom of the easel box.
Here's the finished painting with its many many straight edges, all thanks to masking tape:
