Rubbing Alcohol as Blending Solution with Alcohol Ink

I have been using alcohol inks for a couple of years, but I'm too cheap to buy the official Ranger Blending Solution (since it costs $6-8 for a 2 oz. bottle), so I have been using regular Rubbing Alcohol (70% alcohol) forever. I bought two 32 oz. containers at Costco (I think for about $6) and they have lasted me forever. I kept reading on alcohol ink tutorials that the 90% alcohol was the stuff to buy as a substitute for the blending solution, but whenever I looked for it, the store didn't carry it (most drugstores have it, but I never remembered to look at the drugstore). So, low and behold, I was at Target picking up the weekly necessities, and I glanced in the direction of the rubbing alcohol on the bottom shelf, and they had 90% alcohol rubbing alcohol. So for about $3 for a 32 oz container, it cost the same as the stuff I bought in bulk. So I thought I better compare the two and see if one is really better than the other. I grabbed two white ceramic tiles t...