There are a number of disputed issues and open questions related to soap bubble creation. In no particular order, these are some disputed topics that we hope will become better understood through experimentation and sharing of people's experience.
- Water: Distilled or Tap? Many recipes call for distilled water and many bubblers believe that the minerals in tap water are detrimental to the formation of high-quality bubbles. However, a number of chemists have suggested that the minerals in most tap water are beneficial and that tap water is rarely a problem. The most common dish detergents used by bubblers (various versions of Dawn and Joy seem to be preferred in the U.S.) were formulated to work well with a wide range of waters. It may well be that most tap water is as good or better than distilled water but that some tap water may have problematic minerals. It also may depend on what other additives are added to the bubble solution. This may account for the fact that some bubble recipes work well for one person but not for someone else. Using distilled water will standardize results but may deprive solutions of minerals needed for optimum performance. Some study should be done as to what mineral supplements benefit distilled water. UPDATE SEPT. 2013: The evidence is quite strong that distilled water is very very rarely better than tap. When tap water is a problem, usually simply adding baking powder to the mix (after all ingredients are present).
- Glycerine: Many recipes call for glycerine but some bubblers note that in some recipes the behavior is similar with or without glycerine. Whether glycerine is effective may well depend on the particular detergent, the water and any other additives added to the solution. Some experiments with Ultra Dawn and tap water suggest that adding glycerine has minimal impact by itself. But, when a personal lubricant (such as KY Jelly or a generic imitation) is added along with glycerine that the impact is profound on the bubble-making ability. The combination of glycerine and personal lubricant in this context seems to have a much more profound effect than either ingredient added on its own. The ideal ratio of the two ingredients has yet to be determined. The amount of glycerine recommended in recipes varies widely from 1/4 part glycerine to 2 parts glycerine (where one part is defined as the amount of dish detergent by volume). UPDATE SEPT. 2013: The evidence is quite strong from both my tests and those of others that for outdoor bubbles even large amounts of glycerine (up to 30% of the mix) have a minor impact at best on bubble life. Playing with dilution has a much bigger impact. Smaller bubbles indoors may benefit from glycerine, but a fairly large amount is required for the benefit to be noticeable (i.e. on an order of 15% to 20% by volume).
- pH: The importance of adjusting pH and its effect on bubbles is disputed. Some people claiming that each particular detergent seems to have a pH range that is a "sweet spot". Adjusting the pH to be close to neutral reduces stinging when the solutions gets in one's eyes. UPDATE SEPT. 2013: it has become clear that most bubble juice is at its best with pHs somewhere in the range of 7.0-7.7. For some detergents, the range may be slightly different. This appears to be why baking soda+citric acid or baking powder are effective.
- Ultra vs. non-ultra.
More Disputed TopicsEdit
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There are a lot of open questions that need to be explored to come to a better understanding of soap bubbles and how to make them. The discussion of open questions has moved to its own page.