Gum, Solvents and… Disney World!

Gum stuck to the bottom of a shoe.

Did you know gum has never been sold inside Disneyland? We never considered that until a blog reader shared that insight on our post about why gum does not dissolve when you chew it. It piqued our curiosity so we began a deep look into the issue of gum on sidewalks and the subsequent removal of gum on sidewalks. True to our nature, we didn’t stop there. We managed to go on an exploration from Disney and dirty sidewalks to solvents and stubborn samples– enjoy!

When we received the blog comment the question was asked: how would you remove gum from sidewalks? Sure, you can remove it by purely physical means, scraping. However, that involves a lot of manual labor and could take a great deal of time in a sprawling amusement park such as Disney.

The rubber used as a gum base is not soluble in water, so to remove gum by chemical means would require the use of a solvent that does dissolve the rubber base. Most rubber materials are soluble in ketones (acetone is a very common one). That wouldn’t make sense to use at Disney during the day, as the sidewalks are crowded with people, but after dark is when the true clean up begins, which would make it a great time for a chemical solvent.

Other online sources suggest cooling the gum to make it brittle then “cracking” it off the sidewalk. Some suggest power washing or using orange peel oil or paint stripper. Really though, it comes down to the same principles we experience in our lab each and every day.

This issue may sound insignificant—gum on sidewalks and shoes is more of an eyesore and inconvenience than a major issue. However, the concept of solubility is a very important topic for analytical chemistry. Just as gum is insoluble in water, thus making it a chore to scrape off sidewalks, we often receive samples that are difficult to dissolve for testing, making it a “chore” to prepare for analysis.

Make no mistake though, we don’t shy from the tough stuff and don’t begrudge the task in the slightest. We enjoy the creative exercise that comes with preparing a particularly stubborn sample and will even use solvents others shy away from in this process—like hexaflouroisopropanol (HFIP). This solvent is necessary for polymers that won’t dissolve in other solvents like nylon, Derlin, and bioabsorbable and resorbable polymers.

Sometimes the need to determine the appropriate solvent is more of a mystery because our client does not even know what material they have—therefore selecting a solvent requires forming a hypothesis, testing it, and iterating as needed. Truly, we feel like scientific detectives on these types of projects—as we investigate and dig deep into the challenge.

Beyond the solvent we select, there is also the variable of temperature as we strive to prepare samples. Think about fixing a glass of really sweet ice tea, if you want the sugar to dissolve, it helps to first start with piping hot tea and then cool it once the sugar is homogeneously dissolved within the water. Sometimes a sample is soluble when the solvent is heated to a higher temperature, but at room temperature, becomes insoluble.

So back to gum on sidewalks. Like what we do in the labs—it is an issue of solubility. Although a chemical solvent would expedite the gum removal process, our research shows that a team of hundreds of facilities maintenance team members descend on the park after hours to ensure the pristine standards established by Walt himself are upheld. One task at hand is the scraping of gum.

So from gum on the sidewalks of Disney (or lack thereof) to dangerous solvents and creative approaches to stubborn problems—science is all around us making our experiences more beautiful, meaningful, safer, and enriched.