What substance can produce thick, white smoke that is difficult to control during cremation?

The substance that can produce thick, white smoke that is difficult to control during cremation is zinc. This is primarily due to the physical properties of zinc, which when heated, can vaporize and subsequently condense back into particles that create dense smoke. When zinc is present, particularly in items such as certain types of metal caskets or components containing zinc, it can generate a considerable amount of white smoke, hindering the cremation process and potentially complicating emissions control.

In comparison, while wood, plastic, and paper can produce smoke during cremation, the characteristics and composition of the smoke generated from these materials differ significantly. Wood generally burns cleanly with less smoke when properly seasoned, while paper can create some volume of smoke but does not have the same density or control issues as zinc. Plastic may create thick smoke due to combustion but without the particular challenges linked to the control of zinc-related emissions during the cremation process. Thus, zinc stands out as the material most associated with producing thick, white smoke that is difficult to manage.