Slime—that strange substance that defies Newton’s laws of viscosity—has been a staple in store toy aisles for almost 50 years and the DIY versions have been around almost as long. The typical school-science-project slime recipe involves mixing either borax or contact lens solution with PVA glue and water. The science behind it is a chemical reaction between the polyvinyl acetate in the glue and the borate ions in the contact solution or borax, an action called cross-linking that results in a logic-defying substance that is a whole lot of fun to play with. However, fascinating DIY science aside, too much exposure to boron—which is the base of borax, boric acid, and also, ironically, that contact lens solution—can cause respiratory, skin, and eye irritation, and when ingested can lead to nausea, vomiting, and diarrhea. Note the caution on the front of a box of borax detergent: Caution: Eye irritant, may be harmful if swallowed. Needless to say, that DIY slime hack is not ideal for small children, particularly those who tend to taste-test things. Fortunately for the child in all of us, you can make slime from psyllium husk!
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