In late summer/early Fall 2014, I was making an effort to catalog the color profile of Dawn Pro at various dilutions and with various polymers. In order to get the most meaningful profiles, sessions were only done early in the morning (after sun up) on heavily overcast days (because the indirect light gives the clearest colors). In Central California, where I live, such conditions are sporadic. As I reviewed the photos, I began to recognize that there are a number of potentially confounding issues: temperature (does the temperature influence the film thickness), flow rate, and wick characteristics. Sessions were done to explore the influence of pH on the film thickness, and I settled on pH range of 7.4-7.6 (except for those sessions done at other pHs for the sake of comparison).
Profiing sessions all used a 48" webfoot microfiber topstring and a two strand (white strands) rayon finish mop yarn bottom string. The color profile of the dilutions were remarkably consistent. Work intervened, and I have only recently gotten back to fill in some of the gaps.
In the last few weeks, I have gotten out for 10 to 30 minutes a few times when the early morning humidity was high and the air pretty still to try out some large loops (100" top-strings) with various top/bottom combinations. I have been surprised at how closely some sessions with 25:1 solutions were yielding colors that were more like what I associate with 20:1. Yesterday and this morning, I made some bubbles at 20:1 and noticed that with these giant loops (with lightweight bottoms) that a small change in growth rate could yield a wider range of profiles than I expected.
2015 03 23. 100" Links Wool/Acrylic blend top and 240" orange twine bottom. Note the color difference between this and the other giant from the same session. The rate of expansion influenced the color profile.
2015 03 23. 20to1 juice (with BLM) 100" Links wool/acrylic top and single strand of soda-washed twine on the bottom.
A smaller bubble made with the same equipment has a somewhat thicker film than the two giants. 2015 03 22. Jakey under a big bubble.
Even though this is 20:1, the film (near the loop) has the colors I associate with 25:1 -- a bit thicker than I expect with 20:1 with a bubble this size. Perhaps it indicates that the wick is having no trouble supplying juice even though the bubble looks quite big.