Pretty MAD SCIENTIST stuff there.
You would think you were some crazy chem guy at a University or something !!! Just kidding
Not sure what that would do to grass or pavement or your skin!!!
Perhaps the safety glasses warning should have come first
I’m storing your recipe for reference, sounds a lot cheaper that the HD “labeled” stuff
The nice thing is that for $10 you have enough to do two or three boats.... I roll it on with a roller on a long pole.... then pressure wash. Long sleeves and goggles.
Safety glasses... agreed.... should have come first...
Grass... initially kill it because of pH but if you ran the hose for a long time it might not...but..(from experience) after a few rains the pH will normalize and the potassium from the KOH and the calcium and magnesium from the lime will turn that spot under your boat a very lush green
Pavement... nothing... concrete and cement are carbonate based to begin with so essentially the same stuff with different cations....
Skin.... it will turn the fatty acid oils in you skin into soap (chemically speaking) and they will wash out with the next shower you you will get raw hide for skin until it heals (2 or 3 weeks).
So now the eco-version... if you have toxic bottom paint on your keel...put an old sheet under the boat before you pressure wash... that will catch the toxic bottom paint flecks and you can then throw the sheet away and feel all granola crunch after

. Been there done it...
I've used this recipe on several boats and it always amazes me how well it works. I've used it on ablative bottom paint and also on a bizarre latex bottom job a P.O. did on a boat I purchased. For what ever reason, there will always be one or two small spots that just won't come off ...even after a few attempts... my thinking is they won't come off in the future either so just paint over them.
The scientist in me wants to understand what is special about those stubborn spots. If you could figure that out, you could manufacture some very special application paints.