Sorry Pierre I forgot the quote thing again
In the case of plastisol (a little different when considering waterbase/discharge as small air movement will aid evaporation process) more air will cause for longer curing times on a flash especially in the beginning.
Science side:
1: bulbs turn on heat transfers to the item with the least amount of energy (other factors involved, but quick explanation)
2: if you run room temperature air past the bulbs the heat will transfer to the air essentially cooling the bulbs off
3: The bulbs expend energy heating air
4: This all relates to my previous posts inquiring about the use of a idle circuit