In our previous blog post, we discussed the findings from our research into options and methods for passivating stainless steel. In this post, we wanted to document how we went with actually performing the passivation and a couple of things we learned along the way.
Why Passivate Your Stainless Fermenter?
A quick recap on some of the information we covered in our previous post. Passivating, creates a thin protective film on the surface of metals like stainless steel to help prevent corrosion and rust, remove contaminants and improve the longevity and lifespan of the fermenter.
What to Use for Passivating?
We opted to use the citric acid based version of Bar Keepers Friend powder that is available in Australia to passivate our new Cheeky Peak Nano X Fermenter, since citric acid seemed to be a safe and effective option to use to accomplish this.
There are other acid options available, but we liked that Bar Keepers Friend was cheap, readily available and generally safe to use, unlike some other acids.
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| Bar Keepers Friend Cleanser & Polish powder |
Equipment Required for Passivating
You'll need the following list equipment to complete your passivation process;
- A stainless steel fermenter
- Powdered Brewery Wash (PBW)
- Bar Keepers Friend (BKF) Cleanser & Polish powder
- Protective Gloves
- Sponge
- Pyrex jug or other non-porous vessel/container
Steps to Passivate Your Stainless Fermenter
These are the steps we followed to passivate our stainless fermenter:
- Clean the fermenter with PBW to ensure it's clean. If your fermenter its new this is a good idea to remove any residual oils or contaminants from the manufacturing process.
- Ensure the fermenter is completely dry.
- Put on your protective gloves.
- Mix a couple of tablespoons of BKF with a small amount of water in the pyrex jug (or other container) to create a thick paste.
Our Bar Keepers Friend and water mixture to make a thick paste - You want to get the paste to a thick consistency, but not too thick. We initially had ours a little too thick, so when we tried to coat the stainless surface of our fermenter, it was clumping up and wouldn't spread easily. Thankfully the paste can be easily adjust by either adding a tiny amount of water (or more BKF powder to thicken it).
- Use a sponge or cloth to apply the paste to the inside of the fermenter. Apply it liberally to all internal surfaces that the wort/beer will come in contact with.
- Here's what our first attempt looked like - you can see the paste is clumpy and not spread evenly.
Our first attempt at applying the paste revealed it was too thick/dry and clumped up on the stainless fermenter wall - After simply added a little more water to our paste to thin it a little, we then continued to apply it over the top of the clumps which worked much better. Here's how it looked after applying the paste with a more workable consistency.
Adjusting the paste consistency and it applied much more easily - Leave the fermenter uncovered for at least an hour
- Rinse off the paste covering with water. We found the paste rinsed off very easily with a garden hose.
- Allow the fermenter to air dry - do not dry it off with a towel or any other material
Tip: Make sure you remove all the covers/caps from any of the openings on the fermenter to let the water drain out more easily - otherwise bits of the paste tend to get trapped in these openings and have to be wiped out.
The most important step of the passivation process is to leave the fermenter open and exposed to air. It is this exposure to air that will form the passivation layer.
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| The end result after passivation - shiny! |
All done, your stainless steel fermenter is now passivated! It's a good idea to repeat this process periodically to ensure the passivation layer is maintained.
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