Non uniform coverage may result in corrosion and warranty issues and higher material costs. I get asked that question often. I personally know chemical engineers that are working for the United States Defense Department to designing specific ice-cream flavors. There is not one correct answer to what a chemical engineer does. When I graduated from UB, I had this mind set that what ever is out there and can't be done, a chemical engineer will get it done.
Nothing is impossible for a chemical engineer.
Hope I was able to shed some light as to what a chemical engineer does for a living. Good luck, Nisar. This often involves working with synthetic organic chemists, who have defined the chemical route, and concentrating on both optimizing the synthetic conditions, and defining the means of isolating the material. A specific example of a unit operation I have done considerable work on is crystallization. Because crystallization affects downstream processing, evaluating the effect of crystallization conditions on filtration and drying rates is also important.