pH is not a linear increase but a logrithamic increase in strength. A pH of 14 is 100 times stronger than a pH of 12. As a chemist, we have strong safety warnings for products at a pH of 12. I would have flaming safety warnings about a product with a pH of 14 (something we would never sell by the way.) Use carefully with proper safety equipment. Make sure that you have no holes in your shoes. In talking with one of our Australian distributors, he reported that alot of mates use sodium hydroxide at a 45% strength to clean hard surfaces. Yikes!! I know of someone who got this in his shoe and had to get a skin graft to replace the loss of skin. Be careful out there!!