How do Downy laundry dispensers work?
Dear Straight Dope:
The people who make Downy have this little plastic sphere into which you can put their product. You put the Downy ball in the washing machine, and fabric softener comes out automatically during the rinse cycle. How is that possible? My father says it is because of the change in temperature in the washing machin, i.e., the rubber gasket that seals the Downy ball expands in the hot water wash and contracts in the cool water rinse, allowing fabric softener to flow out through the gap between the gasket and the hard plastic rim. But I fear that dear old dad is no Cecil Adams--his answer seems to be flawed. Why does it still work if you use a cold/cold setting or a hot/hot setting? Please help me, Cecil.
Not to get your father into any hot water, as it were, but those handy little "Ultra Downy Dispensers" are unaffected by temperature.
According to my new-found friend Mary with the USA Consumer Correspondence Team (aka Proctor and Gamble), "when you add a Downy Dispenser to your washload, it floats on top of the water among the clothes in the wash cycle. The force of the spin cycle causes the valve to open. The ball then drops down into the bottom of the washer, where it fills with water as the machine fills and the Downy is dispensed into the rinse water."
In other words, it ain't the heat, it's the motion.
(For those who would like to purchase this handy little gadget, send your name, address and $1.50 (only check or money orders) to: Ultra Downy Dispenser, Box 1094, Maple Plain, MN 55593 Offer good only in the USA.)