It’ s always fun to try new tools, especially when they work well. This time that tool was masking fluid, also known as liquid frisket.
Masking fluid usually consists of latex, water and ammonia, often with some kind of pigment added so you can see where it has been applied. Put some on the paper, let it dry and then you can just pain on top of it. This way it’s possible to preserve highlights or other shapes that would be complicated to paint around.
After trying it out with this quick painting I feel like this is something that I will make use of a lot in the future. I enjoy using my watercolor with lots of water and my painting can get messy at times. It might be useful for other mediums as well, I´m going to look into that.