A diaper is more likely to leak if the baby brother or sister wearing it is dehydrated, Lisa Chumney told children participating in the BASF Kids’ Lab at the Louisiana Art and Science Museum on Jan. 9.

It seems counterintuitive, Chumney said, that less liquid, not more, would trigger a leak in modern disposable diapers, but, as she explained to the children and parents Saturday participating in BASF Kids’ Lab, the proof is in the science of one of the main ingredients.

Sodium polyacrylate, a super absorbent polymer used in these products, can absorb up to 1,000 times its own weight in water, Chumney said.

She and lab assistant Molly Dutel passed out small amounts of sodium polyacrylate powder along with a glass of water, and instructed participants to combine the two and stir.

The two ingredients quickly combined to create a solid, and then Chumney asked them to stir in a small amount of salt. “Let’s see what happens,” she said.

“Absorbing water would be fine, but not everything going into the diaper is water. Our bodies also have a small amount of salt in them,” she said.

Salt, she said, creates an imbalance that nature seeks to even out, which results in the eventual breaking apart of the polymers. With salts introduced, the absorbency of SAPs drops to about 50 times its weight.

Chumney returned to the samples, which participants noted were returning to a liquid state as they stirred in the salt, and produced an endothermic reaction, turning the sample cold to the touch.

“So, dehydrated babies cause diapers to leak, because there’s more salt in the urine,” she said, leading to the breakdown of polymers demonstrated in the cups of water.

The BASF Kids’ Lab presents a series of science-based, hands-on demonstrations designed for students ages 6 to 12, held at the Louisiana Art and Science Museum, 100 River Road, on the second and fourth Saturdays of every month.

Chumney said the program has served 5,850 visitors since September 2012.

For more information, visit the LASM website, www.lasm.org.