Updated March 20, 2015 with 16:1 dilution pictures from March 11 session.
Ever since I first tried Uncle Bubble Ultra Concentrate, I have wondered how it would perform at higher dilutions than the standard 9-to-1 recommended by its manufacturer. To my eye, the film thickness (gauged via its Color Profile) is something along the lines of Dawn Pro at 16:1. Since, UB is based on a totally different surfactant than Dawn Pro, I have no idea how to map changes in dilution from one to the other.
I tried UB at 11:1 last week and was surprised how little of a shift there was in film thickness. The film was a little bit thicker but only subtly so.
I diluted the UB to 14:1. There was a color shift (though not as big as I expected), but bubbles became harder to close. A few days later, I tried the 14:1 solution again after adding some BLM to improve the bubble friendliness. While bubbles were not quite as easy to close as at 9:1, the solution worked quite well and had a color profile more to my liking. There was a lot of humidity. My guess is that the more dilute solution should work a bit better longevity-wise on a humidity-challenged day, but I will need to do direct comparison to be sure.
March 11, 2015. On Facebook, a friend responded to my posting of the 14:1 photo with the comment: "Try 16:1". I did. It needed a little bit of PEO (added as a 1% WSR301 solution very similar to BLM). I have posted some pictures below as well as a color study. The mix was not quite as friendly as at 9 or 11 to 1, but huge bubbles were possible and the longevity was enhanced -- and, in my opinion, so were the colors.