Thickness of oxygen inhibition layer in composite curing is:

When composite is light cured, oxygen in the air causes an interference in the polymerization resulting in the formation of an oxygen inhibition layer on the surface of the composite.The oxygen-inhibited layer is the sticky, resin-rich uncured layer that is left on the surface.Thickness is about 50-500 micrometer. Reference- Sturdevant 6th ed P:237