I re-read the paper you gave us but I interpret it differently. The authors say they used “Rewoquat, a 75% solution of ….” So I read that as the Rewoquat itself is a 75% solution of the active ingredient. When they talk about using it later in the paper they just say they use Rewoquat with no indication of dilution. At least that’s the way I read it.
I don’t know what Rewoquat looks like but the material that Mathew is finding that is supposedly “equivalent” is quite viscous so that further dilution will be necessary. I hoping that Ronny @rleder will get back to us about Rewoquat dilution when he returns from his travels in Germany.