THE HISTORY OF SLIME STRETCHES BACK A WAYS
Like most inventions, this popular stretchy substance is an extension of previous ideas
She lives in the house that slime built. No, the house isn't made of slime. But slime had a big role in paying for it. The house belongs to Karina Garcia, the “Queen of Slime,” whose various videos about making the gooey substance captured the imagination of the public and catapulted her from a “down on her luck” waitress to a millionaire. She now has more than nine million followers on her Youtube channel, has written three popular books about slime and has launched her own line of craft products. Quite a “rags to riches” story that began with Garcia chancing upon a simple recipe for making slime she found on the internet in 2014. Now for a little history.
The toy industry is highly competitive and companies are constantly searching for the next “breakthrough” product. Back in 1976, scientists at the Mattel Company thought they were on to something when they mixed guar gum with sodium borate to produce a viscous, squishy, non-toxic, oozy goo. Indeed, they were. Coloured green and packaged in a little garbage can, “slime” delighted children who were keen to squeeze it, stretch it and knead it. The toy flew off the shelves and was soon joined by a number of imitators.
Like most inventions, slime did not come out of the blue, but was an extension of previous knowledge. Guar gum, a naturally occurring polymer of the simple sugars mannose and galactose, can be readily extracted from the beans of the guar plant. It has an established history of use as a thickening agent in such foods as yogurt, salad dressings, soups and sauces. Then in the 1960s, researchers working on the development of fluids used in fracking discovered that the long carbohydrate molecules of guar gum could be cross-linked with the addition of sodium borate (Borax). The rungs of a ladder would be an analogy for cross-linking.
“Fracking ” is a technique to release natural gas by fracturing bedrock formations where the gas is trapped. Fracking liquid, basically water with suspended sand, is injected under high pressure to create cracks that are then kept open by the sand. The fracking liquid has to have just the right viscosity and that is achieved by gelling it with crosslinked guar gum. The Mattel “inventors” were aware of this technology and used it to create Slime.
Although guar gum and Borax are readily available, the technology to convert these into slime cannot easily be mimicked at home. But in 1986, a paper appeared in the Journal of Chemical Education that introduced a method of making slime that would eventually launch the slime boom and ignite Karina Garcia's rise to slime royalty. The publication described substituting polyvinyl alcohol (PVA) for guar gum, based on the understanding that cross-linking with Borax required the presence of adjacent -OH (hydroxyl) groups on the molecules to be linked and these were plentiful in PVA.
Polyvinyl alcohol was known since 1925 when this water-soluble polymer was patented by German chemists Haenel and Herrmann. It has a number of uses that range from being a thickener in polyvinyl acetate glues to an ingredient in artificial tears for dry eyes. It can be readily purchased from chemical supply companies and I have performed the Pva-borax demo numerous times for all sorts of audiences.
I follow it up by displaying a laundry bag made of PVA along with some Tide Pods. Such laundry bags are used in hospitals to collect bedding from patients with infectious diseases. Since PVA is water soluble, the bag is directly tossed into the washing machine without ever being opened, preventing workers from having to handle infected material. I usually cut a piece from the bag, show that it dissolves in water, and then add Borax to make slime. Disposal is not a problem since bacteria in sewage treatment systems readily biodegrade PVA.
Now for the Tide Pods. These are little packets of laundry detergent that were introduced by Procter & Gamble in 2012. They have various advantages, including cutting down on shipping costs, reducing packaging materials, and preventing the handling of detergents. The technology is based on encapsulating concentrated detergent and additives in a layer of water-soluble PVA. The pods have proven to be very popular, but a couple of issues have arisen. Because they are attractively coloured, the pods can look like candy to children and have been responsible for thousands of anxious parents showing up in emergency rooms with children in tow who are complaining of burning mouth and stomach distress. There have even been a few fatalities. Pod producers have addressed the problem by making the packaging less attractive and including denatonium benzoate, the most bitter substance known. The idea is that any child will immediately spit out anything that contains it.
Then there was the crazy issue of the “Tide challenge” that emerged in 2017 as a result of an internet joke about the similarity of the pods to candies and ended up with people being challenged to eat the pods. Teenagers posted videos about biting into and gagging on pods, which were quickly taken down. There seems to be no end to the stupid things some people will do.
Although polyvinyl alcohol cannot be purchased in stores, Elmer's glue containing it is widely available. Children have had a lot of fun mixing this glue with Borax, following instructions that are readily found on the internet. However, a fly fell into the slime, as it were, when a young girl developed chemical burns on her hands, supposedly from Borax. She had become virtually addicted to making slime with which she played almost every day. Not surprisingly, the media pounced on the girl's unfortunate affliction and slime-making received a big blow. Borax was depicted as a dangerous substance, which it can be if abused, as it was in this case.
Before long, “safe” methods of making slime emerged after someone discovered that contact lens cleaning solutions contain boric acid as a disinfectant. “Borax-free” became the slogan for recipes to make slime with glue and lens cleaner, ignoring the fact that borax in solution actually produces boric acid. Still, using lens cleaner is probably better than handling powdered Borax.
I won't stretch this story any further, but I will leave you with the Guinness record for the longest distance to stretch homemade slime in 30 seconds. That record of 5.19 metres is held by Luke Franks of the U.K. No lens cleaner for him. He is a Borax man.
If there was a record for making the most money off of slime, Karina Garcia would undoubtedly hold it.
joe.schwarcz@mcgill.ca
Joe Schwarcz is director of Mcgill University's Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m. His most recent book is Quack, Quack: The Threat of Pseudoscience, published in September.