How does silly string work

Despite its name, Silly String is very serious about keeping its recipe under wraps. Surfactant is just a fancy name for detergent, which is amphiphilic—both hydrophobic water repelling and hydrophilic water attracting. That attraction-repulsion combination helps glue together molecules in the solution so the string comes out in one solid, silly stream. The stickiness also helps the stuff lightly cling to surfaces—and people—after launch. Shaking the can mixes the solvent-that-shall-not-be-named with the rest of the ingredients, forming a temporary blend of plastics, minerals, and propellants.

Both the water and the solvent quickly evaporate outside the can, leaving the foamy solids behind. The aerosol powerhouse that sends the mixture flying is a relative of Freon, the ozone-depleting refrigerant that pressurized first-gen Silly String back in Already an ACS Member? Choose the membership that is right for you. Discount will be applied automatically at checkout. Your account has been created successfully, and a confirmation email is on the way.

Credit: Courtesy of Rob Oram Spray streamers quickly coat unsuspecting targets. It was, perhaps, an unintended consequence of the wars in Iraq and Afghanistan that a children's toy got an image makeover. Once the domain of Halloween hooligans plastering innocent mailboxes and car windshields, the sticky ribbons known by the trademarked name Silly String got a new reputation as a weapon for heroes confronting a serious kind of terror.

Navy Explosive Ordnance Disposal teams, who defuse and dispose of explosives, have been using Silly String to find booby traps since in Bosnia, says G.

In , Army mom Marcelle Shriver heard a similar story from her son and organized a massive donation of sprayable streamers for the troops, receiving extensive media coverage in return. The hoopla was a boon for the company that makes Silly String.

Patented in the s by Wham-O Manufacturing, the same outfit that brought the Hula Hoop to the masses, the rights to Silly String were later handed off to Car-Freshner , best known for its tree-shaped air fresheners, and Just For Kicks, Car-Freshner's toy division, says Rob Oram, product marketing manager at the company.

The stringy stuff comes in an aerosol can that helps make streamers from the chemicals inside. Wham-O's patent may not contain the current formula, which is a trade secret, but it certainly serves up the chemical principles inside the can.

Silly String, and many of the other half dozen or so spray streamer products sold in the U. The original patent calls for polyisobutyl methacrylate or similar molecules, and a flame retardant such as hexabromobenzene to prevent the eventual dried-up string from catching fire. A touch of pigment provides the color. Spray streamers balance stickiness, or adhesiveness, with an ability to hold themselves together, or cohesiveness.

A few other parts of the original formula contribute to that balance. Plasticizers such as dibutyl phthalate boost the polymer's strength and cohesiveness while ensuring it is still sticky to the touch. Silicone fluids such as dimethyl siloxane make the finished streamers easier to peel away from most targets. A bit of solvent such as dichloromethane keeps everything as a one-phase mixture. Mixed in with the other ingredients is a surfactant such as sorbitan trioleate, which gives spray streamers their light-as-air feeling by facilitating foam formation.

Foams are bubbly materials, and the bubbles get into the spray streamer liquid mixture through their aerosol can housing. Surfactants adsorb at newly formed gas-liquid interfaces, where they lower surface tension and help to stabilize nascent bubbles, says Eric Dickinson , a food chemist with expertise in foams at the University of Leeds, in England. All the ingredients mentioned so far make up only about two-thirds of what is found in today's cans.

The rest is propellant. The patent recommends chlorofluorocarbon propellants such as CFC, which have since been banned in the U. Silly String brand streamers don't contain ozone-depleting propellants; in their place is a propellant that is both nonvolatile and nonflammable, Oram notes. Liquid spray streamers take on their familiar stringy form when they're propelled up a skinny tube and out of the aerosol can. Other ingredients can adjust the strength, stickiness, weight, color and flammability of Silly String.

These include:. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Prev NEXT. A resin forms the plastic structure of the strand. The original formula used polyisobutyl methacrylate , an acrylic resin.

Acrylic resins are also components in materials like Lucite and Plexiglas. A surfactant , or surface-active agent , helps the resin foam and modifies the stickiness of the strands. Wham-O's patent lists sorbitan trioleate as its surfactant. You can see the foaming action of surfactants in ordinary detergents around your home, and you can learn more about them in How Play-Doh Works. A propellant forces the other ingredients out of the aerosol can, causes them to foam and helps form the skin.

The propellant described in the patent is dichlorodifluoromethane , also known as Freon The Silly String manufactured today uses other propellants -- Freon is an ozone depleting substance that is no longer manufactured. Inside a liquid propellant aerosol can. Most Silly String formulations do not require a ball bearing to help mix the product because the ingredients mix well on their own.

Fine Tuning. Plasticizer , which makes the strands stronger and lowers the level of stickiness Silicone liquid , which makes the strands easier to remove from surfaces Pigment Flame retardant.

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