Break down caustic soda once set

[Michelle Bramley]

*I poured biiling water . Left for 5 minutes then blasted it with my titan wet/dry vacuum. It worked first time * amazing vacuum it works for lots of stuff and has the reverse button to blow

[Iggy]

replying to Michelle Bramley, Iggy wrote: Yep, that's good stuff! They make Hydro-Jets that do the same thing, but those let you control and boost the blast.

[Roger Hayter]

It is a bit of a mystery to me how you cause caustic soda to "set" in the first place, or why. It's pretty soluble in water isn't it?

[Jethro_uk]

I have a vague memory that if you drop a lot in at once, more complex chemistry happens which will form an impermeable skin, preventing complete dissolution. A little like aluminium oxide protecting aluminium from corrosion.

Not sure *what* since all that should be there is Sodium, oxygen and hydrogen, with nitrogen available from the atmosphere ???

[Steve]

My guess is that it turned the grease and fat blocking the sink into a soapy solid mass and set.

[newshound]

That is certainly the apparent behaviour if you dump granules in an excess of cold water. I'm not sure it is actually an impermeable skin with different chemistry.

The correct way to make a strong solution is to put the granules in a small quantity of water, ideally in something like a round bottomed flask. It rapidly gets up to near boiling point and dissolves, at which point you can add more if required, finally diluting to the required concentration.

[tabbypurr]

Apply too much & it sets hard. Boiling water is the solution.

NT

[Jethro_uk]

Apparently there are quite a few hydrates of NaOH, and some are solid at room temperature.

NaOH commercially supplied tends to be the monohydrate, not anhydrous.

[Johnny B Good]

Literally, I would have thought. :-)

[Tjoepstil]

in a little water it semi= hydrates and ends up a bit like salt that got wet and stuck together

[Roger Hayter]

Thanks. It's always nice to learn new things.

[newshound]

The secret is to agitate it thoroughly in a small amount of water in a separate container to dissolve it before pouring it down the drain. It will get hot, you might want to cool it down before pouring.

[The Natural Philosopher]

No the answer is to pour it down the drain till it does the above, and then pour a ktlle of boiling water on it.

The supereheated casutibn steam breaks up the chunks and blows the drains cleam

Just wear safety glasses and gloves and an old sweatshirt