Are they vinyl or cloth roller shades? Did you see a project that specified an emulsion? You may need to go Bach to that project to find the answer. All I found, they just painted on the shade.
When you have a question about a project, it's best to ask the creator, using the question section on each project page. This is a general question section so we don't know which project you saw, and therefore can't really answer your question unless we happened to see the same project and remember the details. Wishing you the best.