"Frankly, we didn't have much luck with food grade and went back to the 3%. One reader had a frightening experience with food grade"
This is strange. It doesn't make sense that the 3% should work any better than food grade. That implies that some of the chemical additives in 3% are partly responsible for the positive effects. I am sticking with food grade, I threw out all of the 3% laying around the house. Good article Molly!