Why are aluminum paddles and bowls not permitted for mixing refractories?

Aluminum paddles and bowls are not permitted for mixing refractories primarily because they may react with acidic components present in the refractory materials. The chemical reactivity of aluminum can adversely affect the integrity of the refractory mix, potentially introducing undesired properties into the final product. This interaction can compromise the performance of the refractory, including its resistance to high temperatures and other critical characteristics needed for reliable application.

Safety and material integrity are paramount when working with refractories, as the end-use environments often involve extreme conditions. Avoiding materials that can chemically interact negatively ensures that the refractories perform as expected. Other considerations, such as ease of cleaning or wear rate, while important, do not primarily influence the choice of mixing tools as much as the potential for chemical reactivity does.