The Stress On A Vertical Coating
Here’s a useful quick calculation:
If a coating is applied to a vertical wall the stress due to the weight of the liquid is at it’s greatest at the interface of the coating and the substrate. The magnitude of this stress can be calculated from:
stress = density x coating thickness x g
In SI units: stress is in Pascals, density is in Kg / m3 and g = 9.81 ms-2.
From this, if we know the yield stress of a coating we can estimate the final coat thickness from:
coating thickness = yield stress / (density x g)
This is a popular approach in the chocolate industry where the yield stress of molten chocolate is obtained from a flow curve (ask me if you want to know how), the resulting value plugged into the equation to predict the enrobing thickness for coated wafers etc. You can use it for anything from tile adhesive performance to estimating how much shampoo is left on the inside of the bottle when emptied.