The test matrix is undergoing refinement and this page will be updated as progress is made.
The test matrix is a series of tests that can be used to provide a fairly objective characterization of a bubble juice's characteristics. It is designed to give bubble-makers a concrete way to compare the various characteristics of bubble juices. It is intended to be especially helpful to experimenters in being able to identify the characteristics of a bubble juice using a fairly small quantity of bubble juice and without needing to perform large-scale outdoor tests during initial testing. It is not a substitute for testing outdoors with the equipment for which the bubble juice is intended, but it can help experimenters determine which bubble juices are worth fully-testing.
As I and other bubblers have more experience using and interpreting the results, refinements will be made that should help us make even better use of the results. The goal for the tests is that they should be easy to perform and relatively objective. They give a standard format for evaluating characterisitics so that we can compare our results with the same brews and see if there are conditions that cause different results. The chemistry and physics of bubbles is quite complex and they are subject to influence from a large number of factors -- and having an objective test-bed may help us better understand these factors. It can help give us a sense of how temperature and humidity or water quality may affect a particular brew.
Most of these tests isolate aspects of bubble-making without doing a true simulation of actual conditions. So, the results can only be used to compare solutions and predict how they will behave relative to each other. The size potential test, for example, cannot predict how large a bubble a solution can make -- but it can tell you whether solution A has a similar, better, or worse potential than another solution.
- The Small Wand test. This test determines how amenable a solution is to creating bubbles with a small plastic wand whose outer diamer is 1 inch (inner diameter about .75 inches). Initially, done by gently blowing. The test now uses small fan set up to standardize the testing to reduce variations that resulted from inconsistencies in doing it by hand. A short video of the current (as of Nov. 2010) small wand setup. Video of the original Small Wand Test Setup. The small wand test is relevant to the creation of small and big bubbles. For small wands (both rigid and non-rigid), it gives a general idea of the number of bubbles per wand dip that you can create. And for all wand types (including large tri-string wands) it is an indicator of how easy it is to create a bubble. Solutions with high scores are easy to make bubbles with -- the lower a score, the more challenging bubble creation is. Note that some solutions have very high scores but are not great with very large wands because the solutions are "tight" and don't stretch well enough to make giant bubbles.
- Size Potential test. This test is still being refined. It is intended to determine a solutions relative potential for creating big bubbles (at this point considered over 4 feet in diameter).
- Longevity test. (Refined June 2010). Goal is to determine how long bubbles created by a particular solution last in somewhat controlled conditions.
- Bubble in Bubble test.(Test currently being refined and meaningful results not yet available). This test is meant to record how easy it is to create a bubble in a bubble with a particular solution. Bubble-in-a-bubble is considered a bubble created by blowing on the side of a medium-large bubble.
- Other measures: weight/dip and pH are measured. Weight/dip is intended to capture information about the viscosity and/or self-stickiness of a solution. So, far it hasn't proven to provide terribly interesting information. So, I am not using it for all tests since it slows down the process considerably. The pH of solutions are being recorded as well.
Small Wand Test
This test determines how amenable a solution is to creating bubbles with a small plastic wand whose outer diamer is 1 inch (inner diameter about .75 inches). Initially, done by gently blowing, the test now uses small fan set up to standardize the testing to reduce variations that resulted from inconsistencies in doing it by hand. This test gives a good sense of how easy it is to make bubbles with the solution and a feel for the relative color of the bubbles. The results seem to give a fairly accurate representation of how the solution does for making bubbles up to a 24 to 36 inches in diameter. A short video of the current (as of Nov. 2010) small wand setup.. A short video of the OLD Small Wand Test Setup
The small wand test setup has been improved to use an AC-powered fan (to remove battery strength as an issue and to make the setup more consistent). Video of the new setup to come soon. Here are pictures of the new setup.
Goal is to determine how long bubbles created by a particular solution last in somewhat controlled conditions. The test was designed to control for the bubble film and bubble size. Because humidity and temperature are not being controlled, the humidity and temperature are noted and a control solution is tested that can be used as a point of comparison so that results from different sessions can be compared. A pint mason jar is filled up to the 6 ounce mark. The mouth of a small water bottle whose bottom has been removed is dipped into 1 teaspoon (about 5 ml) of bubble solution. The water bottle is then lowered into the mason jar which forces air up and creates a bubble. A timer is started when the bottle is done being lowered. The time is noted when the bubble bursts. This test is not meant to accurately assess minute differences in bubble longevity rather it is (like the other tests) designed to record fairly large-scale differences.
Size Potential Test
This test is intended to determine a solutions relative potential for creating big bubbles (at this point considered to be bubbles over 4 feet in diameter). A wire hoop is held in front of a small fan and the maximum length that the resulting tunnel achieves is measured as is the time it takes before it pops. Analyzing the maximum length requires the test to be recorded on video. The video is analyzed to find the maximum lenght that each trial achieves. Five trials are conducted for each solution. So far, this helps to distinguish between solutions that do a great job on small and medium size bubbles but that do not perform well for large bubbles. This test is needed because I have found that viscous solutions that work great for creating bubbles up to 2 to 3 feet in diameter (and less) do not work so well for creating bubbles over four feet (in any dimension). It is appearing that very viscous solutions are too 'stiff' to grow to accommodate big bubbles. It may be early to make such a generalization but that is currently (2010 05 28) how it seems. While a wire loop is very different from a tri-string wand, initial test results indicate that the relative performance of bubble juice with the 5-inch wire hoop does correspond to the relative potential of the solutions with a tri-sring wand (at least for wands with a 48-inch top string). Sterling Johnson suggests -- and it seems reasonable -- that there may be another size break for much larger bubbles. So, this test may not apply to the creation of huge bubbles. The initial tests were done with the same fan used for the Small Wand test, but recent tests have used an AC-powered fan at its lowest setting. A comparison of the two fans with the same solutions needs to be run to see if either provides more useful results.
The wand used for the test is a bare metal wand and quite unforgiving. The benefit of this is that it seems to unmask weaknesses in the solutions and it is easy to clean when changing solutions. At the end of the test, the wand is also used to try to make successful bubbles rather than just letting all the bubbles be broken. Since the wand is quite unforgiving, if bubbles are made successfully with it, it is a good indication that it is a generally friendly solution.
Improvements to explore. It needs to be explored whether there is a fan-to-hoop distance for the size potential test that will capture the tendency of a solution to stretch vs. its tendency to form a bubble. For example, some "stiff" solutions have a very strong tendency to break into spherical bubbles while others do not have such a strong tendency. Those with a strong tendency are very friendly for making sturdy medium-sized bubbles but the film will break if you try to make too large a bubble. Such solutions are not amenable to making big bubbles in spite of their friendliness.
See the other pages in the Test category for examples of the test matrix in action.