What could be a consequence of not properly calibrating the spray gun used in fireproofing?

Not properly calibrating the spray gun used in fireproofing can lead to inconsistent application thickness and performance, which is why this choice is the correct answer. Proper calibration ensures that the spray gun delivers the fireproofing material at the correct pressure and flow rate, which helps to maintain a uniform thickness across the applied surface. Inconsistent application can compromise the fire resistance properties of the material, leading to potential safety hazards if the coating does not meet the required specifications for fire protection.

In contrast, improved application efficiency, achieving a competitive market price, and increased aesthetic appeal of the finish may not occur if the spray gun is not calibrated correctly. These outcomes are often secondary to the fundamental requirement of ensuring a consistent and effective fireproofing application. If the product is not applied uniformly, it may lead to areas that are under-protected or over-saturated, both of which can diminish the fire-resistive qualities necessary for safety and compliance with building codes.