When I say light I mean ambient light, not thinking someone would place jars in direct sunlight or close beside a light. I have never hidden my jars away from whatever light is in the room they are, it is not a significant pinning trigger. Consolidation, drop in co2 levels, evaporation, and then light. That is the reason not to peek into a tub or tray before full consolidation, not because of the light but in the drop of the co2 level. If a tray or tub is fully colonized it will knot and pin without a drop in co2 but it will not be an even pinset, likewise an unconsolidated tray or tub will knot and pin if co2 drops. Evaporation is not possible without a co2 drop so thats number 3 on the list of triggers. Light is a distant 4th, as you can grow mush in the dark if you have the other 3 factors.