I take no credit for this information. I copied it off the web and cannot re-establish the link. It is very useful and thanks to whoever posted it, if anyone knows its origin please let me know so I can give them the credit. Richard
“Caustic Soda (Sodium Hydroxide or NaOH) is a dangerous chemical and can cause serious injuries when not handled correctly. Always take precaution and wear protection like gloves and glasses when handling Caustic Soda. Never add water to Caustic Soda crystals, always the other way around.
In South Africa home brewers have a limited range of cleaning and sanitizing agents. In the US they have the home brew chemical Starsan and other specialised cleaning chemicals.
One chemical we do have is Sodium Hydroxide (NaOH) or more commonly named Caustic Soda. It is widely used to produce soap and also does a good job at cleaning out your drains and does wonders for cleaning your home beer making equipment. It is available from hardware stores and some supermarkets and is very affordable. However it is sold in a crystal form and must dissolved in water. This is where care must be taken, and mix in the order stated:
Caustic Soda 30% Solution
1. Pour 2l of cold water and pour it into a pyrex or stainless steel pot, do not use normal glass as this will shatter seeing as when the caustic soda reacts with water it get boiling hot.
2. Next add 500g of Caustic Soda crystals, obtainable from supermarkets or hardware stores, to the cold water. Wait for the solution to cool down and pour it back into a normal glass bottle.
This solution is approximately 30% sodium hydroxide and can be used to clean fermentation equipment, beer kegs, beer lines etc. Use gloves and protective eyeware when using it and avoid splashing it on your skin.
· Fermenter: Dilute 4ml of the solution per liter of water, warm water is better, and let it stand overnight.
· General Cleaning (excl Aluminum): 4-10ml of the solution per liter of water, warm water is better, and let it stand overnight.
· Kegs: Pour 100ml of the solution into the keg and fill the keg with water, leave it overnight and then rinse 3-4 times with water before use. Alternatively you can just pour 30ml into the empty keg and top it off with 2l of boiling water, turning the keg in a different position every half hour to ensure the mixture gets into all the crevices of the keg. You can leave the mixture in the keg until you are ready to use it, just rinse with boiling water before making use of the keg.
· Beer Lines: It’s recommended that you clean your beer lines every three weeks, this usually goes hand in hand with cleaning your kegs. When you’r done cleaning your kegs leave the solution in the keg, apply some pressure to the keg and simply push some of the caustic soda mixture through your beer lines. Leave it for 20 minutes and then flush with beer through the tap and lines.
Please take care when handling Caustic Soda, never pour water directly onto the Caustic Soda crystals. If you should get some of it on your skin wash it off immediately. You will know it’s off when your hands don’t feel soapy anymore. As with any chemical, use it in a well ventilated area.
The solution can be kept in a normal glass bottle for long periods and should last you quite some time.
This article was adapted from the SouthYeasters Caustic Soda cleaning guide.