I'm having problems measuring the temperature of a steel surface with varying emissivity with a pyrometer. So I thought one way to overcome the varying emissivity is to paint the surface with a paint that has a high uniform emissivity in the IR region. The paint should: Have high emissivity in the 7-15µm range and be transparent in the visible range. Not change it's emissivity in the temperature range 50-200oC. It is also preferable that the paint is non-toxic. Does anyone know of a paint that matches these criteria?