Cleaning with Caustic
Most home brewers have a distinct advantage over commercial brewers and one of the biggest advantages they have is when it comes to keeping their equipment clean. It is fantastically easy to keep home brew equipment clean compared to commercial equipment and the reason for that is access. At the commercial scale, there are so many places that you simply can't reach, either because the equipment only has a single entry/exit port (fermenters, for example) or because it's simply dangerous to enter the equipment (CO2) or because there's just too much of it (pipework) to realistically disassemble, clean properly and reassemble.
Here, we discuss Sinner's Circle, which sounds like some sort of demon summoning apparatus, but it's named after Dr. Hubert Sinner who came up with in in 1959 to relate the various aspects that go into keeping something clean.
The Sinner's Circle has four parts: Chemical, Mechanical, Temperature and Time. Each of these relate to an aspect of keeping something clean. It also means that a deficiency in one of these must be made up with by another.
For example, that pot you left in the sink overnight to soak because you didn't feel like scrubbing it? That's using Time to make up for a lack of Mechanical action. In a commercial brewery, there are two aspects of the Sinner's Circle that are almost always lacking: Time and Mechanical. You simply don't have time to tear everything apart to soak it and you can't reach most of it anyway. Sometimes mechanical action can be augmented with water pressure, but I've seen countless examples of a hunk of krausen ring that will not budge no matter how high the water pressure, yet it comes off with the first wipe of your hand.
This means that you need high powered chemicals and a lot of heat to clean anything. At the home brew level, however, you can see every surface that needs to be cleaned so it's not an issue. Most of the time.
There are a couple of places where you absolutely will need to bring out the big guns. The situation is a little bit different though because most homes don't have the ability to shoot supersaturated steam through things. At most, you'll get some boiling water, and if you require a lot of time, that heat will dissipate fairly quickly. Let's use the example of a plate chiller.
In a home brew plate chiller, you cannot disassemble it to clean (you usually can at the commercial level though). You absolutely need to keep it clean though because it's on the cold side of things, meaning that anything that grows in it will have the potential to pass along infections. You might be able to soak it in some PBW, but PBW loses cleaning power pretty quickly and the temperature will cool overnight, so you're left only with time. Eventually, even time won't help and something will start growing in your plate chiller as it's supposed to be soaking.
Using Caustic Soda
That's where caustic soda comes in. It should be noted that the caustic soda that commercial breweries use is not the same as the caustic soda that you can get your hands on as a home brewer. The caustic soda commercial breweries use has a couple of extra ingredients added - a surfactant, an antifoaming agent and a chelating agent. This removes the hardness from water which improves the efficiency of the caustic soda. For home brewing purposes, you don't need to care about foaming and mixing your solution with distilled, RO or softened water will remove the need for chealating agents. Surfactants help keep the solution from beading, which is useful if you're relying on sheeting action, but you won't be cleaning anything big enough for that to be necessary.
So how do you get your hands on this stuff? You're looking for food grade lye - it's used in baking, as well as soap making, as well as drain cleaning (that's how well this works). Once you've received your order of caustic soda, there are some safety precautions that absolutely need to be followed before moving on.
- Wear your PPE. That means some long, preferably silicone brewing gloves, eye protection and make sure the rest of you is covered. No brewing in shorts and sandals for you today.
- Add caustic to water, not water to caustic. Caustic soda is extremely reactive (which is why it works so well) so as soon as it hits the water, it will cause an exothermic reaction. If you're actively dumping water on top of it, you get aerosolised reactions happening.
- Keep a bucket of water nearby in case you do splash some on your skin or get some in your mouth.
With that out of the way, let's get ready to clean!
The first thing you want to is get the proper solution ready. Your caustic will come in some sort of rough powder, which is a good thing because a fine powder can get up your nose really easily. The ratio you're looking for is ~10g/L, or about 100g per 3 gallons if you prefer to measure that way. This will give you close to a 1.5% solution which should be suitable for your needs. You can go up to double if you absolutely need to, but I've never found any problem that a 1.5% solution can't handle.
At this point, you can choose to soak, or recirculate. If you've got a plate chiller, or RIMS/HERMS tubes, I'm going to assume that you also have a pump that can handle that. This will add some sort of mechanical action and reduce the amount of time that soaking requires. It also means that you don't end up with the heat loss that can occur with a long soak.
Be warned that some of the things that come out of the other end may horrify you - especially if you've waited a long time to clean it. You might want a strainer to catch some of these globs so they don't end up being recirculated back through your system.
HERMS being cleaned with caustic. This is after it was cleaned with PBW and StarStan
Once you're done being horrified, make sure to rinse well - also with distilled/RO/soft water. Hard water has a chance of precipitating some of the caustic and you absolutely do not want that hanging around - especially if you're using it for your tap lines. Lastly, you're going to need to passivate. Mix up your favourite acid based cleaner and run that through. If you don't passivate, you can easily end up with pitting happening on your stainless steel. That leads to rust forming, which will ruin your beer almost as quickly as an infection.