Using Caustic Soda safely

I bought some from the chemist in the form of drain cleaner as I wanted to try stripping anodize with it but reading about this highly corrosive substance is really putting me off!! ;_;

I also read it reacts with aluminium producing hydrogen gases. So it might not be safe to do this indoors?

How do you use it? What do you mix it in and what do you wear/what precautions do you take when mixing and handling?

P.S. I read sort of conflicting advice here too. >.<

I have only ever used this to clean out drains and frankly this is all I would use it for.

It’s also used as an oven cleaner…it’s Sodium Hydroxide…We use it as a testing reagent in swimming pools. It’s also great (IN A DILUTED FORM) to remove the yellowish haze off of your car’s headlights (but will leave streaks on the plastic, you have to get a very very fine sandpaper to buff these streaks out)

Use either glass, or lab-grade plastics to store and dilute it. When you are diluting it, always add it to the water, never the water into it. If you have PURE sodium hydroxide, I don’t know what you’d need to dilute it to, but I’d say atleast 1:10 with water is a good starting place, and you can strengthen or dilute it from there.

Note: I take no liability for what I have said here. I handle the product already in a liquid dilute form on the daily as a part of my job. Pure soda is pretty serious stuff. I heard from my high school chem teacher of a colleague of his who dropped a small pellet of it in the back of his shoe, it started dissolving into the back of his heel, but it also kills the nerves. it wasn’t until he felt his shoe “sloshing” from being soaking wet with blood he looked down to realize it was tearing him up. It literally turns your organic skin into soap :slight_smile:

Its also used to make soap.
From what I know and have used of lye, the amount of concentration is where the dangers become higher. Low solutions (Water and lye) are not as dangerous. I have had it on my skin many times in low concentrations (Do not try this). Oven cleaners are commonly made of lye as there active ingredients. I use oven cleaner to clean burnt motor oil off of (steel) auto parts before machining. Works better than any degreaser that I have tried. I can tell you that it will eat your skin if left for 10 seconds or more. Its not ever given me any pain, just some new shinny skin. I assume it just eats at the first layer, and if left to long could eat several layers. If you do get it on you Quickly rinse with water thoroughly. I would recommend you wear eye protection. And don’t stick your face directly over the solution breathing the fumes. Use some pliers to pick the object in and out of the solution or a stiff wire (coat hanger).
Warning : Don’t touch the stuff just because I did, your concentration could be higher causing burns.
The lower concentrations of a lye solution like used to dissolve anodizing is quite weak. I only use about a teaspoon for 1/2 gallon of water. I add more if the anodizing seems to be going slowly. If you would like to make smaller amounts of solution, just add very little lye and see how it reacts in 5 minutes if it doesn’t seem to be doing much add a little more, then check again until the desired stripping is achieved. Rinse in water thoroughly once done.
As for the hydrogen fumes, The lower the concentration the lower the fumes. I would think if you de-anodized beside a open window where air is flowing, you would be fine. Hydrogen is lighter than air so it goes up. I don’t really think there’s much danger from the hydrogen unless you where in a closed up room and de-anodized for a long period of time. Where the hydrogen could concentrate at the ceiling.
I consider de-anodizing some what dangerous. But take precautionary measures to try and keep it safe. The eyes being the most important part needing protection. Gloves would not be a bad idea either but you should really not be touching the stuff any way, if you use something to take the item in and out of the solution. Don’t touch it because I did with the oven cleaner, your concentrations could be higher. Don’t take safety to lightly.
This is just my 2 cents on de-anodizing with lye.

Thank you!

The stuff I got is small crystals in a HDPE bottle, and it said on the label for use as drain cleaner to mix 50g to 1 litre of cool water (not cold). Since I had to weigh it I used a Pyrex jug on my scales.

I wore an FFP3 mask, protective eye glasses and rubber gloves, and turned the extractor on with windows open.

I tried some as drain cleaner. Although I didn’t add all the 50g at once it didn’t seem to dissolve fully (I thought it was melting the bottom of my mop bucket but it was undissolved crystals). I couldn’t tell if it warmed up much either but I think it has warped the bottom of the bucket! I rinsed it straight away.

I will have to check my buckets to see if I have one in HDPE first, and if I do then I will do it by the window.

Do you just rinse the aluminium in water afterwards?

I have nightmares about that stuff. We used it at a factory that I worked at and I have been burnt by it a few times it’s really really nasty if you get it on you you had better have a ton of water ready to rinse and rinse and rinse with. It seems you have taken good precautions and yes rinse the aluminum repeatedly too.

I have a friend who now has this great golden retriever that he uses instead of his eyes thanks to this stuff. He was splashed with it while putting 16 foot by 4 foot steel plates into a caustic bath. The water and caustic has separated out because the mixer had broken down, the engine kicked back on as he was putting the plates in this cause it to mix back together too fast and it basically exploded, gallons of it went flying all over. We hosed him down with fire hoses and rushed him to the hospital. He was doing the same job that I would normally have been put on that day except our line operator was out sick so I got bumped up to that job and he got stuck with the cleanup. Of course we were always supposed to be fully suited up for the job but it was over a 130 degrees inside the factory that day and he didn’t follow the rules.

I won’t go anywhere near the stuff.

It really does sound like the stuff of nightmares. :~

I checked my mop bucket and it’s polypropylene which according to this it’s safe so it must have warped from general use.

I was also concerned it would splash when pouring but this didn’t turn out to be a problem. I will try it on an old Maglite soon!

Just please stay safe and take care. Knowing that it’s dangerous is usually half the battle anyway.

I will!

I remember when I used Mr Muscle oven cleaner I only wore gloves without knowing what it was. Now I know I will take extra care with that product too.

What, pray tell, will you do with the Mag?

Its the opposite of acid. Back to school with you. My degree is in chemistry, don’t let the chemical scare you. As long as you practice a little safety and common sense you should survive the ordeal. Thick rubber gloves are a must and safety glasses would be nice. Use glass bowls when you can and plastic spoons for the scooping. Never use heaping scoops as two little scoops are about the same and tend not to spill over. As far as the hydrogen gas generated its not enough to become explosive, but a good bit of ventilation goes a long way. When finished use lots of water to wash it down the drain then let the water run a few more minutes when its all gone. Glove can be soaked/rinsed for a reuse. Try wearing polyester clothing when dealing with caustic soda, cotton tends to dissolve in the wash after splatters. After clean up use even more water, like a good shower to get any off of you.

The bottle it came in has a narrow cap/opening so I have to pour it into something. :~

Are pyrex bowls okay? I’d feel safer using something with a good handle like the bucket or measuring jug.

I don’t have any wire coat hangers so I’m unsure what I can use instead to suspend the aluminium inside.

I’m not sure yet, I just want to see what happens to it! :bigsmile: Provided I can get it apart nicely. I will clean it first too.

Hydrogen is actually nontoxic. And in the amounts being created by deanodizing flashlights, there is little to no danger of asphyxiation. It is, however, quite explosive in a wide range of concentrations in the air. So keep the cigarettes (and other ignition sources) away. And it is probably best to keep the windows open to prevent a fire. But otherwise, hydrogen is the least of your worries when working with sodium hydroxide.

I’ve read greased lightning strips anodizing, people say it has no fumes, no pitting & seems ‘non-toxic’. Sounds like the best option by far.
MSDS for Greased Lightning indicates sodium hydroxide / lye is an active ingredient. Perhaps its a lower concentration or there is a magic secret additive. :crown:

Since reading reports of greased lightning I would only recommend pure lye to those trying re-anodizing.

I had to look up the MSDS on Mr Muscle. Some solvents, sodium hydroxide and MEA as active ingredients. Now I feel bad for the poor rats and rabbits they tested it on. :_(

Its not the hydrogen fumes I was worried about. Its the caustic soda fumes, don’t want to be breathing that down your lungs.

haha saw this thread and laughed. according to Payday 2; Caustic soda, Muriatic acid and Hydrochloric acid combined makes, ummmm, a drug which will remain nameless. Id stay away from that stuff if I were you, also seeing as how its very hazardous and combined with one wrong thing, it will explode/burst into flames

anodize stripping, id suggest oven cleaner in a bucket and dip the part for 3-5 minutes. any longer it will eat away at the metal and create small pits which will need to be sanded away

Another Chemist weighing in. Texas Shooter is right. This is base, not acid. It can be worse than acid in some respects. If you get concentrated solution on your skin, it will start saponifying your fat in your skin - turning it into soap, and very difficult to wash off. 50g in 1 liter of water will be about 1.25 M, not extremely concentrated, but I would especially protect your eyes with goggles and hands with rubber or nitrile gloves. Take care not to splash the stuff around, and you’ll be OK. To use as drain cleaner, I would think you would need a more concentrated solution. It does not dissolve immediately, and exotherms as it dissolves, becoming warm or hot (and thus more dangerous). I would make the solution in a polyproplyene bottle or some other robust plastic. Glass may be attacked to a slight extent.

My caustic soda plastic container has a large opening which I just use a spoon to measure, so I cant be of much help there.
You do however want to keep the lye dry. A air tight container. Lye draws in moisture in open air.
You don’t have to suspend the Maglite in the lye. You can wrap the wire around the Maglite or through the Maglite if its disassembled. Or just a wire with a hook to hook the pieces to remove them.
It might help to find a plastic container with a bottom that’s just a little bigger than what the pieces would need to fit into, all on the bottom. Use just enough water to cover the pieces. Use a chop stick or something to move the pieces around in the solution, so you can see if its working to your liking. When the pieces have been de-anodized pour the solution down the sink with lots of fresh water, leave it running. Then run lots of water over the pieces while still in the plastic container. The lye should be diluted enough for you to rinse by hand now. Rinse very thoroughly. Then dry. You don’t need a big container or suspend the parts. The smaller container will keep the solution to a minimum and use less lye. It will also help in seeing the pieces. We are talking about a very diluted solution of caustic soda. In stronger concentrations it is very dangerous as you can read in post above.
Almost forgot to mention, if you will use warm water it will help dissolve the caustic soda crystals. Not hot water and you can use the chop stick to stir very lightly to help dissolve, you don’t want to make any big splashes.

This sounds pretty dangerous. Surely this can't be the only alternative to grease lightning.