Tag Archives: Chlorine Gas

On the Quest for Lye

This is part three in an n-part series about soap. Check out the other parts if you’re interested. Part one: On the Quest for Soap and part two: What is Soap?

Our living room reeks of chlorine. You don’t notice it too much if you sit in the room awhile, but if you leave for just a few minutes your nose adjusts back to smelling normal air so when you return you’re hit with a wall of chlorine. It smells like a swimming pool even though there isn’t a swimming pool within a quarter-mile of us. It smells like someone mopped the floor with bleach but no one did.

The room smells like chlorine because I’m making chlorine gas. That’s not my goal but it’s a side product of my goal: making my own lye.

I said in the bread post how I love getting as close to the source of things as I can. Baking bread means I don’t have to pay some guy at the bread factory to make it for me but you can only go so far back before you hit another wall. In bread’s case I still need to buy the raw ingredients. Flour, oil, salt, yeast. And none of these products are within my reach. I don’t know how to grow or harvest wheat, where are you supposed to get salt from besides the store?, and oil I could make but it would be messy and a pain in the ass. (The idea would be to buy oil sunflower seeds, the black ones, from Farm and Fleet. It’s sold as bird seed but you could smash them up and harvest the oil. Maybe I’ll actually try that…HMMMMMMM!)

Soap is oil and lye (sodium hydroxide, which sounds a lot cooler than ‘lye’). I mentioned how getting oil would be a pain in the ass, but what about lye? You wouldn’t think so — it’s a harsh industrial product — but it’s apparently really easy to make with only three ingredients: salt, water, and electricity.

If you read the sodium hydroxide Wikipedia page it tells you it’s created by something called the chloralkali process. To sum it up: get salt water, pass electricity through it, and you’re done. Sodium hydroxide. Lye. One of the two things you need to make soap.

The details are a bit tricky though. You can’t just toss a battery in a cup of salt water and get a glass of lye. As the reaction proceeds (its called “electrolysis”) it forms a bunch of nasty stuff that eats most metals. The actual wires (electrodes) you use need to be non-reactive. Good metals are crap like gold and platinum; these are way out of my cost range! I tried this with aluminum foil (it’s cheap and easy to find) and it just deteriorates after a half-hour. The aluminum doesn’t just disappear though, it reacts to form other compounds. Instead of lye you’d get something like sodium aluminate or aluminum chloride or whatever. I don’t even know. But using aluminum means there is a contaminate in the water and that’s not going to be helpful.

The two electrodes also give off hydrogen and chlorine gas. Hydrogen is cool because it’s hydrogen. Rocket fuel. Flammable balloon gas ala Hindenburg. Etc. Chlorine gas is toxic, but in the small amounts I’m making it shouldn’t (???) be a problem.

And that’s why the room smells like chlorine.

(Fun fact #1: chlorine gas is the reason cleaning products instruct you to never ever mix them with anything else! Most of them will make chlorine which isn’t good to breathe in. Go give it a shot if you’re curious. Mix some bleach with ammonia/glass cleaner/toilet bowl cleaner and take a teeny tiny smell of it. It’ll choke you, it’ll burn your nose, and it’ll make make you feel like you’re having an asthma attack. I recommend you do this outside unless you want to piss your family/roommates off.)

(On second thought, do not do this. I’m not taking the blame for your stupidity.)

If you have the two electrodes in the same glass, the chlorine and hydroxide react to form sodium hypochlorite — bleach — simple household bleach. Fun huh? If you need bleach try making some yourself. I might try to conjure some up just to try it, but bleach isn’t important enough to worry about when soap is the goal.

Here’s my setup. Two glasses of salt water. There’s a paper towel between them acting as a bullshit cheap “ion channel” so the current can flow between the glasses. For electrodes I bought some carbon ones off Amazon. Carbon, yes. It’s basically really fancy and thick charcoal. (Fun fact #2: before I ordered those I tried a few bits of charcoal from our bonfire pit. It sort of worked but the charcoal fell apart at the slightest disturbance.) The positive electrode makes chlorine gas while the negative makes hydrogen. (Another fun fact #3: if you bottle up the H and the Cl and burn them together you get hydrogen chloride gas, a toxic and acidic gas! If you bubble this through water you get hydrochloric acid! Capturing gasses is difficult though, so I’m not worrying about it.) 

How does it work? The ions in the water, the sodium and the chloride, wander near to the opposing electrode. The chlorine goes bye-bye (it’s a gas) and the sodium can’t evaporate so a hydrogen from the water goes bye-bye. This leave a lonely OH- that used to be water hanging around. The negative electrode ends up with a bunch of these hydroxide ions (OH-) hanging out around it, a sodium strolls on over, buddies up with it, and makes sodium hydroxide.

I guess the big question is “Well, does it work?” Maybe. It sure makes a ton of hydrogen and stinky, yellow-green, pungent chlorine so it’s doing something. I also bought some pH papers to measure the acidity/alkalinity of the water, and the positive one is sitting at 3 (a mild acid) while the negative glass is somewhere between 12 and 14 (a strong base). So once again something is there, but I have no clue how to get the lye out of the water or anything.

Don’t do this (obviously) but I tasted the lye-water and it doesn’t burn or anything. The pH papers say it’s basic as hell, but it does nothing to my tongue.

After letting it run on my solar power for about four days there is some cloudy white stuff at the bottom, about a half-teaspoons worth. Maybe it made so much lye it’s starting to precipitate out of the water? I think that’s what’s happening. Drain the water off and boil the solid dry I guess. Maybe find a solvent that dissolves either salt or NaOH but not the other? But is that all I have to show for the past four days? Apparently so. I put maybe a tablespoon of salt in each glass so the amount of lye created should be somewhat similar; I won’t end up with ten pounds of the stuff using a tablespoon of salt.

I’m going to replenish the water and salt and keep it running until I get a sizeable amount of lye. Is it worth it? Hell no, and I don’t know what I was hoping to accomplish. Maybe if I ever sold my soap I could slap the “totally homemade at home using solar power and range-free lye!” label on it. Someone would love to buy something as green as my soap. But I probably just wanted to try it to see if it’d work. Make some homemade soap from some homemade lye (and maybe homemade oil…); it’s about as homemade as you can get. No lye from drain cleaner and big industrial factories. Sadly that lye is a whole lot easier to acquire and a hell of a lot cheaper.

Closing Note: I moved my ‘production apparatus’ outside to our driveway. This way I don’t have to worry about filling the house of with fucking chlorine gas and having DCFS called on me.

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