Kaolin could be in special boxcars, but chances are any one plant would recieve it in only one type of car. Tank cars would be most common.
Paper ships in almost any type of clean 40-60 ft, uninsulated boxcar. The caveat is that the plant will want to use only one type of boxcar for each type of paper product. So they might load paper for milk cartons in plain unequipped 50 ft boxcars (think RBOX type cars, 50 ft exterior post cars, bought by the IPD roads in the 1970's). But they will want only those cars because they set up a pattern of loading and bracing in the car. If you give them different car types they have to change their loading pattern, may not be able to get all the shipment in the same number of cars and could have more damage to the paper. They might use one type of car for newprint and and another for brown kraft paper (bag paper).