Letter to the editor

In response to the article on Gluep, a non-Newtonian material (Chem 13 News, November 2011), there are a number of items that need some attention, and I am adding some additional information.

Elmer’s Glue putty was a common material made by science teachers in the 1970s. At that time, it was made using Elmer’s Glue (an emulsion of polyvinyl acetate) and liquid laundry starch. There came a time, however, when laundry starch would not work. It took multiple inquiries to the company making the laundry starch until we received the explanation that the company had removed borax from their formulation. From that point forward, making Elmer’s Glue putty with borax was a common activity.

I found that sodium tetraborate decahydrate is soluble in water at a rate of 3.9 g/100 g H2O at 30°C (Lange’s Handbook of Chemistry) and used a saturated solution of borax with some solid remaining at the bottom of the solution since 1979.

Slime, from the toy store, is composed of guar gum, not PVA, as determined by personal communication with the head chemist at Mattel Toy Corporation in 1979. I first presented the preparation of Slime at ChemEd 79. The use of PVA for making Slime was introduced by David Weil (deceased) of Shady Side Academy, Pittsburgh PA, at ChemEd 81. Guar gum Slime, if properly cared for, has a long storage life; PVA Slime does not. I currently have no confirmation that PVA is used in commercial Slime.

Gak, a sister product of Slime, was later marketed by Mattel in the late 1980s. It was also composed of guar gum. I found that a variation of the Elmer’s Glue putty would approximate Gak by simply adding one teaspoon measure (5 mL) of talcum powder (baby powder) to the mixture.

Another product, an elastic form of Gak, marketed about 1990, was called an Ooz Ball. Although I cannot disclose the actual formulation of the Ooz Ball, I was able to approximate its properties by adding an oil-free moisturizer, such as Revlon Clean & Clear™, or equivalent, to the Elmer’s Glue Gak formulation.

Additional formulations for Slime and these materials, along with other information on related materials, can be found on my Chemistry in the Toy Store page of my website.

An additional note on making a PVA solution:  Measure 960 mL of room temperature water into a large beaker or heatproof plastic container. Measure 40 grams of polyvinyl alcohol. Add the polyvinyl alcohol to the water slowly, with stirring. Place in a microwave oven. Heat the mixture, on high, for one minute. Open the oven and stir the mixture. Heat for one minute, open the oven and stir the mixture. Continue heating for one minute intervals, stirring after each heating cycle, until a clear solution is obtained. Avoid boiling the solution. Remove from the oven, cover with aluminum foil and allow the solution to cool. Pour the solution into a properly labeled bottle and seal. The solution can be stored indefinitely.