There has been some discussion about why PEO and HPMC (and HEC) affect bubbles the way they do. There has been some speculation that changes in surface tension may play into their effects. I have been looking for some simple ways of measuring surface tension and after evaluating the DIY methods, I decided to see if drop size was sufficient to detect changes in surface tension among solutions that have different characters.
I used an eyedropper with marking at .8 ml and .4 ml that came with a package of infant Motrin. Below is a table that summarizes my findings tonight. The solutions with PEO and K15M (a type of Dow HPMC) used the amounts found in Jumbo Juice -- simply as a point of departure. I also did an abbreviated 'small wand test'. The amount of PEO was sufficient to significantly potentiate the water/detergent mix (which by itself gets a small wand average of 1) -- it also resulted in a noticeably stringy solution. The K15M mix scored exactly the same as straight detergent/water. So, I need to continue adding HPMC until it makes a difference and then measure the surface tension.
The PEO had a small but measurable impact on the surface tension. Note that more drops means smaller drops which indicates lower surface tension. So, it appears that this amount of PEO solution slightly raises the surface tension compared to the straight water/detergent mix.
Follow-up needed: create PEO + K15M solution. Create K15M solution that has enough K15M to have a notable change on the small wand results
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| Trial # | tap water | Dawn Non-Ultra | Dawn Pro Pot & Pan | Non-Concentrated Classic Dawn | 11:1 tap and P&P | 11:1 tap and P&P plus PEO | 11:1 tap and P&P plus K15M |
| 1 | 9 | 16 | 15 | 12 | 17 | 15 | 17 |
| 2 | 8 | 14 | 15 | 14 | 18 | 16 | 18 |
| 3 | 9 | 15 | 16 | 14 | 19 | 16 | 16 |
| 4 | 8 | 14 | 13 | 14 | 17 | 15 | 19 |
| 5 | 7 | 15 | 15 | 13 | 17 | 16 | 17 |
| Avg | 8.2 | 14.8 | 14.8 | 13.4 | 17.6 | 15.6 | 17.4 |