It is at this stage that any adjustments caused by the sulphur dioxide checks are applied to the basic thickness. Manufacturers must next ensure that no slate will be thinner than this measurement. Because slates are sold on the foundation of nominal thickness; in case the range difference are great the moderate thickness is going to be much bigger than the minimum. If thevariation is smaller subsequently they will become much closer. This procedure ensures your slates will be technically satisfactory but there is a different route in which it is important for conservation grounds to use denser slates. These can be specified based on traditional construction methods. Obviously it can be unwise to use this alternative to indicate thinner slates than required to resist the wind stress.