This additive is designed to completely replace the usual water in the water:powder ratio of the specific gypsum product being used, and should not be diluted for use.
Whip Mix does not test different dilutions or percentages of increased/decreased strength.
One difference is that Whip Mix suggests that you use one milliliter (1ml) less of the Gypsum Hardener than the water called for in the water:powder ratio listed in the Directions for Use. Example: if the suggested W:P ratio is 20ml water to 100grams powder, you would use 19ml of the hardener to 100grams Powder).
In addition to the chemistry, less total liquid in the mix results in an increase in the physical density of the stone, thereby increasing the hardness and reducing the brittleness.
Tests have shown an increase of 2-3 MPa in a three point bend strength test (tensile) where 1MPa = 145.04 psi.