How to turn baking soda into washing soda

It's time for chemistry in the kitchen! 

Q: Why would I need washing soda?

A: So you can make your own laundry detergent! It's a natural water softener and stain remover.

Q: Can't I just buy washing soda at the store?

A: Probably, but I couldn't get to the store. Also, this method may be cheaper depending upon your energy costs.

Arm & Hammer Washing Soda wasn't available through Safeway.com, and Amazon.com carries it, but with a ridiculous price mark-up (no doubt to compensate for the free shipping). If it's difficult for you to find in your area, try this simple recipe:

How to turn baking soda into washing soda in your own kitchen

You will need:

baking soda

an oven

baking trays (not aluminum)

spatula/turner

airtight container

Set your oven to 400° F. The process will actually work at 270° or greater, but you don't want to wait around for that, do you?  Pour the baking soda into your trays. I used one tray for each pound, so the powder was shallower and had more surface area for the reaction.

Bake for an hour. I stirred it a couple of times to ensure even heating and exposure. I read that it doesn't hurt to over cook it, so I didn't keep a close watch on the clock. When a friend picked me up for dinner, I just turned off the oven and let it cool in the trays.

Here's a little science lesson while you wait for the magic to happen:

Baking soda is sodium bicarbonate (CHNaO₃), while washing soda or soda ash is sodium carbonate (Na₂CO₃). When baking soda is heated, carbon dioxide and water are given off. 

If not stored in an airtight container, it will absorb moisture from the air, and lose its potency. Which makes me wonder, how effective is the stuff sitting in a cardboard box on the supermarket shelf?

Once the powder cools, store in a clearly labeled airtight plastic canister.

baking soda --> washing soda

Lessons learned: I found out later that washing soda is not recommended for cleaning aluminum, which explains why one pan was left filmy. The coated cookie sheet came out of the dishwasher just fine.

Also, I know the number one rule in chemistry lab is to not use the taste test, but I couldn't resist. How could I know that it really was no longer baking soda? So I stuck a finger in and touched it to my tongue. Ewww! It was soapy and not at all zesty and tangy like baking soda. I rinsed my mouth out right away. It's not toxic, but very caustic and can irritate the skin and eyes. I didn't notice a big hole in my tongue, and I haven't died from it yet, but I'd recommend you take my word for it. And if that's not enough to convince you, read About.com's chemistry column.