Sciencemadness Discussion Board

Cleaning dishes with NaOH

MeshPL - 13-3-2016 at 02:32

So... It may seem that vast chemistry knowledge may be not very useful in everyday life. However I think that this one piece of knowlege is could be potentialy useful.

I started wondering why nobody is using (solutions of) NaOH to clean their dishes. It's cheap. It's enviroment friendly compared to regular surfactants. It is sure anti-microbial. It cleans fats and proteins well. You could probably use a 1 bath to clean a pile of dishes with little effort. The only bad things about this, are the facts that:
-it is dangerous (but so are knives)
-it may corrode the dishes (although the rate may be dependant on the materials, stainles steel cutlery should be resistant, so are plastic ones, ceramic and glass dishes are a different thing)
-when washed of with hard water (containing calcium and magnesium) it will leave a residue. Nothing a little dip in HCl before final washing wiyh water can't fix, however.

What do you think guys? Is it the future of everyday kitchen?

j_sum1 - 13-3-2016 at 02:45

Well, NaOH is traditionally used in spray-on oven cleaners but is generally on the way out because the aerosol fumes are a bit harsh to breathe in. That and the fact that it is a good marketing spin to say, "contains no harsh chemicals" or "non-caustic".

So, yeah, it could be done but convincing people it is a great idea for their dishes would be problematic.

Round here, NaOH is used as a drain cleaner. It is pretty pure too. (Unless you buy the version with bits of aluminium turnings in it.) Also standard bleach contains NaOH as well.

One difficult thing is that it does tend to mess up the skin on your hands -- worse than acids IMO.

I think the idea is reasonably sound but marketing the idea would be an uphill battle and I don't think it would fly.

unionised - 13-3-2016 at 02:50

Quote: Originally posted by MeshPL  
So... It may seem that vast chemistry knowledge may be not very useful in everyday life. However I think that this one piece of knowlege is could be potentialy useful.

I started wondering why nobody is using (solutions of) NaOH to clean their dishes...

I do.
It's easy, and I'm lazy.

Sulaiman - 13-3-2016 at 03:15

NaOH for dishwashing is not a good idea in my opinion because;
. risk, especially to children ... far more dangerous (eyes etc.) to children than diluted surfactants/detergents.
. need to always wear sturdy glove ... removal of fats causing dermatitis
. incompatibility with aluminium
. how to make large profits selling cheap stuff ?

MeshPL - 13-3-2016 at 04:03

I mean, I don't wanna sell NaOH. I wanna use it and promote it's usage. I should try using this in the near future.

I know safety is the issue. It's doubtless. But whith planned setup it shouldn't be a big problem. Just set up a setup where there are two deep containers, one with NaOH, one with acid (NaHSO4 wouldn't be a bad idea, and some amateur chemists will have it as a leftover from making HNO3 and other things). Additionaly there should be two hangers and a plastic basket with long handles. Just put dishes in a basket, dip into NaOH, wait, hang basket above NaOH, to let it drip down, repeat with NaHSO4, wash with a bit of water.

Mabus - 13-3-2016 at 04:30

Using NaOH to clean your dishes is not a good idea mainly because most porcelain and its glazing tends to have lots of alumina, which dissolves in strong bases and will slowly corrode your dishware. Glasses might not be an issue, but you'll need very pure sodium hydroxide, which the store grade might not be, due to various toxic impurities.

hissingnoise - 13-3-2016 at 05:07

Quote:
I mean, I don't wanna sell NaOH. I wanna use it and promote it's usage. I should try using this in the near future.

You might want to tame it with stearic acid first . . . oh wait . . .

unionised - 13-3-2016 at 05:35

Quote: Originally posted by Mabus  
Using NaOH to clean your dishes is not a good idea mainly because most porcelain and its glazing tends to have lots of alumina, which dissolves in strong bases and will slowly corrode your dishware. Glasses might not be an issue, but you'll need very pure sodium hydroxide, which the store grade might not be, due to various toxic impurities.

In fact, it works just fine. I've been doing it for years and the glaze still seems to be on the plates.
Odd as it may seem, I rinse off the NaOH afterwards. this also removes any impurities that might have been in it.

Mailinmypocket - 13-3-2016 at 06:07

I use it to remove baked on crap from "Pyrex" baking dishes from time to time. Works great. It's just the hardware store stuff, white prills. It's not a very safe thing to have in every kitchen though. It's horribly dangerous to the eyes and lots of people are clumsy and/or irresponsible and will have accidents.

Otherwise it works wonders on glass and porcelain

BromicAcid - 13-3-2016 at 07:34

If you think NaOH is good, why not ammonium bifluoride?

blogfast25 - 13-3-2016 at 09:18

Quote: Originally posted by BromicAcid  
If you think NaOH is good, why not ammonium bifluoride?


Because you're comparing apples and oranges.

I've used 15 % NaOH to clean carbon encrusted SS pots (no Al of course), Pyrex dishes and our kitchen oven. Sometimes also badly charred lab glass ware. Works a treat and there's no etching effect.

Here it's sold as the thickened version, which already makes it a lot safer.

NH4HF2 doesn't have the same effect on carbon-rich encrustations but, depending on concentration of course, does etch glass. And water soluble fluorides are very toxic and will cause very painful skin burns.

Little known fact: the use of HF in car washes:

https://www.carwash.org/docs/default-source/safety-resources...

[Edited on 13-3-2016 by blogfast25]

BromicAcid - 13-3-2016 at 11:30

Apples and oranges? I thought we were discussing potentially hazardous chemicals that can do a heck of a job cleaning glass? Any difficult to remove spots on our glassware at work either get a KOH/EtOH soak or an ammonium bifluorde soak. We use it all the time, we have dispensers for it, and it works great. Yes, it's more hazardous than NaOH, but my understanding was that this thread was looking at these compounds assuming they could be handled safely. The solutions we use are only about 2.5% and they work great.

Anyway, the only reason we have to use things like ethanolic KOH is because you cannot reach the inside bottom of the flasks to mechanically expunge the junk. With a Pyrex baking pan that's not an issues so some elbow grease can determination can go a long way. So long as you don't let that stuff start building up. For those interested here is an article on the best home remedy:

http://www.goodhousekeeping.com/home/cleaning/tips/a32751/be...

Love that I'm linking to Good Housekeeping on a chemistry forum.

unionised - 13-3-2016 at 11:33

Among the differences is that I can buy caustic fairly cheaply from the supermarket.

blogfast25 - 13-3-2016 at 12:06

Quote: Originally posted by BromicAcid  
Apples and oranges? I thought we were discussing potentially hazardous chemicals that can do a heck of a job cleaning glass?


I thought we were discussing washing dishes with NaOH. Would anyone, even with simple (and effective) precautions, use dilute NH4HF2 for that purpose?

[Edited on 13-3-2016 by blogfast25]

aga - 13-3-2016 at 12:26

Erm, no.

"for hands that did dishes to drip as soft molten flesh, use wild green* scary liquid"

This is better :-
https://www.youtube.com/watch?v=Y_LaVvSIT_8

*poetic licence.


[Edited on 13-3-2016 by aga]

ave369 - 13-3-2016 at 21:38

The idea of using strong chemicals to clean badly fouled kitchenware got into my mind, too. But I have a problem other than greasy dishes on my mind: how to clean hard carbon residue from aluminium saucepans? Obviously, some strong oxidizing mixture is needed, but which will not corrode aluminium itself?

MeshPL - 13-3-2016 at 23:07

90% HNO3 doesn't dissolve aluminium, it makes it passivate. Pretty sure more dilute nitric acid also works.

annaandherdad - 14-3-2016 at 09:08

About 10 years ago my mother had some dishwasher detergent whose active ingredient was NaOH. It was a kind of gel, and intended for automatic dishwashers. I don't remember the brand name.

hissingnoise - 14-3-2016 at 09:37

Quote:
But I have a problem other than greasy dishes on my mind: how to clean hard carbon residue from aluminium saucepans.

My wife cleared out all our aluminium cookware some good few years back over concerns about its toxicity!

All we worry about now is chromium leaching from SS . . . :o

Magpie - 14-3-2016 at 09:58

I keep an ethanol/NaOH solution handy for periodic cleaning of glassware or use when there are especially stubborn deposits. I have been distilling terpenes which left a resinous deposit in the pot. This would not come off with repeated scrubbings with hot water/dish soap. A few hours at room temp in the ethanol/NaOH bath took it right out.

vmelkon - 17-3-2016 at 15:49

Quote: Originally posted by hissingnoise  
Quote:
But I have a problem other than greasy dishes on my mind: how to clean hard carbon residue from aluminium saucepans.

My wife cleared out all our aluminium cookware some good few years back over concerns about its toxicity!

All we worry about now is chromium leaching from SS . . . :o



We have received a pan made of glass as a gift. I guess it is borosilicate glass. It is about 30 cm in diameter and 3 cm high. It is good for making eggs.
There are pans of all sorts of shapes made from glass.

ave369 - 18-3-2016 at 06:21

Quote: Originally posted by hissingnoise  

My wife cleared out all our aluminium cookware some good few years back over concerns about its toxicity!

All we worry about now is chromium leaching from SS . . . :o



Discarding aluminium cookware is NOT an option for me.

Mabus - 18-3-2016 at 14:50

Quote: Originally posted by unionised  
Quote: Originally posted by Mabus  
Using NaOH to clean your dishes is not a good idea mainly because most porcelain and its glazing tends to have lots of alumina, which dissolves in strong bases and will slowly corrode your dishware. Glasses might not be an issue, but you'll need very pure sodium hydroxide, which the store grade might not be, due to various toxic impurities.

In fact, it works just fine. I've been doing it for years and the glaze still seems to be on the plates.
Odd as it may seem, I rinse off the NaOH afterwards. this also removes any impurities that might have been in it.


I assume you don't use a very concentrated NaOH solution and you don't leave the plates in it for days? That usually is no problem.

Schleimsäure - 4-4-2016 at 07:24

I actually used it in the dish washer a few times. Put it in the chamber where else the commercial tablets fit into.

Worked well.

macckone - 4-4-2016 at 09:15

No scrub oven cleaner.
Works on most metals and they have varieties that are safe for
self cleaning ovens. Self cleaning oven lining is ceramic so that
handles most dishware. I would not recommend these on aluminum
or plastic as they contain a corrosive mix of ammonia and amine based
compounds with some kind of hydroxide.
It will dissolve all but the most carbonized crud and that includes
aluminum and plastics. The good news is the most carbonized
crud usually just flakes off with a light scrubbing after a good soak
of the cleaner because whatever was holding it together just
got dissolved.

Some of the varieties may be safe for aluminum and plastic
but I would check the label.