I was watching one of Ben Komets' videos and saw at 1:13 here https://www.youtube.com/watch?v=RbdOID8RouA where he uses this item that can test how thin your paints are. I would like to know what they are called and where I can find them.
they look like swatches but instead of colors for paint consistency.
For tutorials it's good to see what a light-basecoat for him means (you basically just see how much the paint covers the white sign in the black square).
For home... not that necessary, or if you want to check if your paint is thin enough use simply a newspaper. The idea is the same, you check how much of the text is covered by your paint.
After an hour of searching I found it. Kind of silly really. He sells them on his website. http://www.benkomets.com/shop/. They are dilution helpers by MOJO.