Shade 5 faceshields, can you get darker

Hello, I'm currently doing arc spraying. I'm using full face respirator connected to air, sunnies and shade 5 face helmets. Is there anything available darker in the face shield so I can ditch the sunnies. I welding helmet does not fit over the full face respirator.
The arc spray book suggest that you use a shade 8 lens from memory. The boss does not seem to thing using the shade 5 visor is a problem because you never look at the direct arc coming out o the machine.
Any help would be good or a way to make the shade 5 lens darker.