lavenders19 wrote:
I have recently seen the sulphuric acid to clear blocked drains.
Having googled around, it seems I should not mix the 2. I am trying
the caustic soda today followed by boiling water and detergent.

When you mix solid caustic soda and water, the mixture gets
hot. It can get very hot, and boil. When it boils, it can
and will spit hot caustic soda granules/boiling caustic
solution all over the place. If you pour boiling water onto
solid caustic soda, the temperature of the water will probably
immediately go up a bit, to above boiling, and it can and will
*violently* spit boiling water/steam/caustic solution/granules
all over the place.

The above is why it is recommended to mix the caustic into
cold water, carefully, to avoid being showered with caustic.
Read the side of the tub for more info.

You should avoid being showered with hot (or cold) caustic,
use eye/skin protection, and keep some vinegar and a pail or
two of cold water handy to wash in if there's an ewmergency.

If anyone tells you that the above isn't true, then they're
fools.


If that fails, how long should I wait before i move on to the acid?

Make sure there's no caustic in the system before using acid,
or it will cause a violent reaction. Flush it with water first.

Quite frankly, I think you'd be better off dismantling the
system to do a proper job. Good Luck and take care.