Which factor does NOT affect the rate of char?

The factor that does not affect the rate of char is the type of fire extinguisher used. The rate of char refers to how quickly wood or other combustible materials develop charred surfaces during a fire, which can be influenced by various aspects of combustion and material properties.

Ventilation effects play a significant role in the char rate, as they can impact the availability of oxygen and heat, altering how quickly materials burn. Similarly, the moisture content of a wood product affects its combustibility and char formation; wetter wood tends to char more slowly due to the energy required to evaporate the moisture before combustion can proceed effectively. Additionally, wood density is relevant because denser woods generally contain more fuel within a given volume, which can influence the rate at which they char.

The type of fire extinguisher, while crucial for suppressing flames and controlling fires, does not have a direct impact on the char rate of materials. Different extinguishers may use various agents (such as water, foam, or powder) to combat flames, but in terms of the charring process itself, this consideration does not alter how quickly wood will char when exposed to fire. Thus, it is clear that this factor does not influence the rate of char formation.