The Thirsty Bag

TypePart #SupplierUrl
ifixit.comIF145-163iFixithttp://www.ifixit.com/Tools/Thirsty-Bag/...

The Thirsty Bag is a simple, inexpensive, and effective response to electronic water damage. It uses top of the line Molecular Sieve to quickly and consistently pull all of the water out of any device you leave inside. The special beads are engineered to grab water molecules out of the air, and never release them. It can reduce the atmospheric humidity to 1% RH and remove all liquid water overnight.

Why it Works ¶ 

Modern, low voltage devices typically do not "burn out" immediately upon water contact. Instead, tiny microscopic beads of water in chip housings and on circuit boards are re-routing the power erratically to places it doesn't belong. This can cause a cellphone to malfunction, or not work at all.

This means, luckily for us, that if you can remove all the water from the phone it is likely to work again. Unfortunately, this is not as easy as it sounds. Water will cling to the smallest spaces where towels and sponges can't reach. We can't heat the phone to get the water out, or we may cook the sensitive flash memory, or melt delicate components. So we must turn to science to get our phone dry.

Liquids, in an atmosphere, will reach what is called an equilibrium vapor pressure. Which means that liquids will evaporate into the atmosphere around them until the atmosphere reaches a saturation limit based on the temperature. We recognize this as air drying. It is why when you spill water on your linoleum kitchen floor and leave it till morning, it will be gone. Water will continue to evaporate into the atmosphere until the atmosphere reaches this equilibrium vapor pressure*. This means if we keep drying out the atmosphere, water will keep evaporating. This allows the Thirsty Bag to maintain an extremely low vapor pressure in the bag, and suck the water out from the tinniest cracks in the phone.

*About 2.5% RH at room temperature

Reviews ¶ 

"... A good deal that will offer peace of mind for those who have any worries at all about spills"

- iSource

"iFixit's new "Thirsty Bag" can very effectively clear liquids from electronics."

- Cnet

"The iFixit Thirsty Bag can be a life-saver when it comes to salvaging water-damaged iPhones and iPads… if you happen to have one around when an accident happens."

- iMore Reviews

Homebrew Tactics ¶ 

Rice ¶ 

A common recommendation to those with wet phones is to use uncooked rice. Theoretically this would make sense, as it appears to do the same thing as Molecular Sieve while being readily available to anyone with a well-stocked kitchen.

Unfortunately, rice is not an effective desiccant for a couple of reasons. Rice has a low capacity for atmospheric absorption. It may absorb the liquid water on the case, but our real problem are the tiny drops inside. Also, as rice sits on your shelf, and the shelf at the store before you bought it, in unsealed boxes and bags it slowly sucks in water out of the atmosphere around it, reaching it's absorption capacity. Thirsty Bag Molecular Sieve pouches are sealed at the factory where they are made, and not exposed the the atmosphere for longer than 2 minutes during packaging where they are resealed and prepared for you.

Heating Methods ¶ 

A bad idea is to cook your phone to evaporate all the water. Like was said above, increasing the temperature will increase the equilibrium vapor pressure, causing more water to be evaporated. In reality, the temperatures necessary to properly dry a phone with heat will actually damage the memory in the phone, and melt some plastics. The sun won't come close.

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