To understand their significance and, therefore, underlying performance, both dry cup and wet cup properties need to be appreciated.
What makes them work is the wet cup performance, not the dry cup performance.
When we start looking at composite materials and assemblies such as OSB covered with fluid-applied water resistive barriers (WRBs) (Photo 3) or gypsum board or OSB with integral water resistive barriers (Photo 4), all three characteristics need to be considered: dry cup, wet cup and inverted wet cup.
Only Preference is a true pre-mix, incomplete without the addition of fresh foods, though the product literature encourages you to add up to half a cup of "extras" to each dry cup
of The Honest Kitchen's other products.
Most striking when comparing the data and looking at the cumulative distribution function of the measured mean values, is the wide spread found in the dry cup data (test condition C1) of the gypsum board finished with the latex coat.
The highest measured mean dry cup value of gypsum board finished with latex paint is more than ten times larger than the lowest measured mean value.
Both dry cup testing and wet cup testing establish a 50% RH difference across the test specimen.
It's dry cup value is 1 perm, so it meets the code requirement of a Class II vapor retarder as tested under ASTM E-96 Test Method A (the desiccant method).