Hopefully someone here has had a similar problem and can help me out. I have to paint a section of wall at my work 18% gray for a photo booth background. The local paint store looks at me like I'm from Mars as they have no idea what 18% gray is. Does anyone know the color mix formula for 18% gray
You should be able to get an approximate neutral 18% gray by mixing carefully a pure black and pure white paints, something in between 40% white 60% black and 50-50.
The issue is not only getting the correct color, but the correct level of reflectivity. Look at an 18% gray card. It is a very flat surface. There is no stray reflection. Most good quality house paint is intended to be washable. That means it dries with a somewhat shiny surface. Not what you want.