Household Isoprophyl Alcohol is usually 70-90% strength..not sure what the other 10-30% is, could be water? I have some 98% in my lab, it doesn't flash fast like denatured alcohol. I keep denatured alcohol in my shop..but use a clean stiff nylon bristle brush to clean glass and lams before glue up. I have used denatured on glass once and didn't have a problem..