Natasha writes: Do drawings made with polychromos & paint thinner need a protective layer to prevent smudges? (I tend to use hairspray for black pencil drawings).
While you aren’t specifically asking about using hairspray with your graphite pencil drawings, I’m going to start here. STOP DOING THAT!!! This has been a practice with art for so very long. I remember being in high school and the art teacher telling us to do this. I totally get that someone at some point told you that this was an acceptable thing to do but it just isn’t if you want your work to last.
Companies who produce hair spray do not care if their product yellows with time. They don’t care about it being PH neutral. These things don’t matter because they are to be applied to hair temporarily. They aren’t testing for how it reacts to artwork and how it holds up over time. Krylon makes some great sprays that you can use to protect your artwork. Everything from UV protection to just keeping it from smudging.
This leads us into your actual question about protecting your colored pencil work. The polychromos do not need to be sprayed with anything, you just want to frame them behind glass. If you’re working with prismacolor and you’re having an issue with wax bloom, prismacolor makes a spray to seal the work and prevent this from happening when you’re finished.
No matter what type of spray you decide to use on your work (graphite or colored pencil) do a test on a scratch paper (the same paper your project is on, with the same pencils) to make sure that specific spray plays nicely with the supplies you’ve used. I’ve heard where some of the sprays didn’t play nicely with different types of colored pencil, so you always want to test first.