The exposure time was about 8 hours.
He had hoped his chair(s) would go on to be mass-produced, not hand-crafted. As a matter of fact, he had hopes that much of his furniture would be mass-produced--he aimed for simplicity in construction. The pieces of wood that comprised the Red Blue Chair were the standard lumber sizes readily available at the time.
The answer is 350 takeaway 400 then take away 50