Readers of this blog know that I have been interested in whether or not baking soda + citric acid has a beneficial impact on bubble solutions and that I have been having surprisingly good results with an HEC-based bubble mix that includes baking soda + citric acid on some dry days when my PEO-based solutions barely work.
I have wondered whether this HEC mix needs the baking soda+citric acid. I have noted elsewhere that it seemed like baking soda+citric acid was benefitting my PEO-based mixes but that the difference was subtle enough that I wasn't sure that it was responsible for the difference.
The conditions have been too windy most days lately when I have had a little free time to do any testing. On a few evenings (one which was very dry -- around 40% humidity -- and another with higher humidity -- around 55%) I have step outside and tested HEC-based solutions with and without baking soda/citric acid and found there to be a seemingly unmistakable difference. The solutions without baking soda/citric acid frequently popped while the wand was being spread or very early in bubble formation. It was difficult to make a bubble more than 5 feet long. The solutions with baking soda/citric acid were easy to make 20 foot tubes while walking either slowly ore briskly). Those tests were done with Dip Stix. The difference was so extreme (during the dry session) that I swapped Dip Stix because I was concerned that the particular pair Dip Stix were the problem.
Unfortunately, since this was outside at night, I couldn't get any video.
About a week ago, I finally had a few minutes on a day with decent humidity and wind that wasn't too strong. The conditions were still a bit "poppy" in spite of the humidity. Possibly this is due to a lot of pollen in the air. Despite the 60% to 65% humidity, I had a few premature pops with all solutions. Several weeks ago, when I first start exploring with the HEC-based solution, I didn't have any premature pops even in extended sessions. During that period, we were coming off a very wet spell. I believe that in those circumstances, the rain did had done a good job of saturating particles in the air -- and perhaps the end of the rain has triggered a wave of pollen.
Here are three video clips from a head-to-head test of HEC-based solutions with and without baking soda+citric acid. The humidity was between 60% and 65%. Conditions were not completely unchanging but were similar enough for me to feel pretty confident that the difference in behavior is primarily due to the difference in the solutions (as the differences were consistent with the trials that weren't tapes).
The lines in the gutters are approximately 10 feet apart and the street is approximately 25 feet across.
Watch in HD if you can (you will need to pop out the YouTube display)
SOLUTION 02A (no baking soda/citric acid)
SOLUTION 02B (Solution 02A with a bit of Solution 01 added)
The difference was so extreme that after testing solutions 01 and 02A, I used the loop from test 01 with solution 02A and had the same terrible results. Solution 01 contains HEC, baking soda and citric acid. Solution 02A has no baking soda or citric acid. Solution 02B is solution 02A with the small amount of solution 01 that was left. There is no more than 1/4 part solution 01 in 02B.
Recipe: 16 parts tap water, 1 part Dawn Pro, 8 grams CellosSize QP100MH (HEC) per gallon of added water (not solution), 3.2 grams baking soda per gallon of added water, 1.6 grams of citric acid per gallon of added water.
Follow-ups need to be done to make sure that the behavior wasn't due to some contamination of 02A or some other reason. I also will be doing tests to look into the optimal amounts of the ingredients and whether both baking soda and citric acid are required or if one of the ingredients by itself is primarily responsible. (It seems likely that both are required and that the action has something to do with the formation of sodium citrate). There will also be follow-ups to see if this difference is apparent when the mix is made with distilled water as the chelation impact of citric acid has been suggested as a possible factor. I will also test to see if the order that the ingredients are added makes a difference. Alan McKay has written that the baking soda should be added to the water followed by the detergent and then the polymers with citric acid last.
During this same session I also explored a 20-to-1 PEO-based solution that had baking soda/citric acid added as it occurred to me during my night-time tests that the difference that it was making in the HEC-based solutions was so significant that it might help the 20-to-1 mix that has been failing so miserably. It hasn't turned the 20-to-1 mix into anything amazing but it has made it much much better than it has been in any previous trials. See March 29, 2011 Session and also April 02, 2011 Session.
20-to-1 PEO-based solution with baking soda/citric acid
You may want to see the terrible sessions listed above as points of comparison (not quite fair since they were on days with different conditions). PEO is 0.01% supplied by J-Lube.
PEO and HEC-Based solutions combined
Question: did this improved the behavior or the PEO-based solution?