Mixing Different "High Strengths"

Yes, simply mix the bases in whatever proportion you desire. If a hardness halfway between the two is what you desire, mix equal amounts of each base together, and be sure to use the proper amount of catalyst for each base. The result will be a 15-17 shore A hardness High Strength 2.5

They are brother sister products and are very compatible. You can also mix more of the High Strength 2 than the High Strength 3 to make it a little bit more stiff ... such as 80/20 and the result would be higher towards a 20A.

Great question and thx for the comment on our products. Let us know how it works!
thx,
Mike