Everyone makes mistakes. So I got good news and bad news.
The bad news first.
When you make a mistake with watercolors, it’s not like a digital painting where you can just hit undo. Also, watercolors aren’t opaque either so covering it up takes a little bit of creativity.
Then how do you fix mistakes with watercolors?
Well, here are the two things that I personally do..
Dilute it then paint over it
If it’s not too bad, you can dilute it with water. You simply take your clean brush, get it plenty wet, and clean up the mistake as best as you can with your brush and a piece of your paper towel.
Then hopefully, the mistake isn’t bad enough that when you paint over it, it doesn’t show through.
Some people will use watercolor ground to fix a mistake. The problem with that is that watercolor ground is sort of like Wite-out. This may be before some of our readers’ time, but Wite-out was a product that people used back in the pre-computer days. When you made a mistake with ink, you fixed it with Wite-out, waited for the Wite-out to dry, then wrote over it.
The only problem with this is it shows. If you use too little watercolor ground, it fails to cover up the mistake. If you use too much, you can clearly see the watercolor ground.
So really, your best method is to water it down, wipe it off with a piece of paper towel (some people prefer Q-tips), and paint over the mistake. And hopefully the mistake isn’t significant enough that you won’t be able to do this. Like for instance, if you spill a good amount of paint on the painting, you’re best off either somehow incorporating that paint into your painting or throwing the painting out and trying again.
Incorporating the mistake into the painting
If possible, this is the way to go. The Bob Ross method – taking a mistake and pretending you meant to do that.
I love Bob Ross. I love his mindset. Also, he was a pretty good artist.
If you’ll be unable to dilute it and paint over it, you can always do something creative to incorporate the mistake into the painting. Like for instance, a really ugly part of your sky could be covered with a monochromatic bird (a bird in the distance). Or you could cover an ugly part of your water with a rock. Or put a tree in your background that covers up your oops in a landscape scene.
The possibilities are endless. Just think of what could go there and work that mistake into your painting.