The iStill Catalysts are filled with copper packing. The copper is there, because it plays an important role in the distillation process: it takes care of sulfur compounds that may have developed during fermentation. Copper reacts with sulfur and creates a more enjoyable drink. But copper does not just react to sulfur. Copper also reacts with oxygen. In doing so, copper rust is formed, and that's a bad thing for primarily two reasons:

1. Copper rust easily breaks loose in small particles that can carry over in the final spirit via the vapour path, thus potentially creating copper contamination in your drink;
2. Copper that's rusted dramatically increases the column's surface area, thus increasing vapour speeds* as well as decreasing reflux speeds**.

We dealt with the first issue by making our columns out of SS instead of copper, and by placing the copper catalyst as low in the column as possible. The second issue, of copper rusting, when in contact with oxygen, is dealt with in two ways:

1. Maintenance;
2. Cleaning.

We make our iCatalysts from glass. That way you can see if the copper SPP starts to rust. The colour change of copper is evident, when it rusts, and the glass does not hide the rust formation process from sight. iStill developed the Easy Lifting System, that goes with the iCatalyst, so you can easily remove the copper SPP from the catalyst and put it under 45% strong alcohol. That's the maintenance part: if you don't distill for over 48 hours, put your copper SPP under 45% alcohol, so oxygen can't get to it. But what if you didn't do that? Or what if you ran a very sulfur rich fermentation through your iStill and through the iCatalyst? Discoloration will take place. And discoloration means rust formation and rust formation means sub-optimal performance. In short? When your copper is rusted, you need to clean it. Here's how:

1. Take 2 liters of water;
2. Add 0.2 liters of hydrogen peroxide (3%);
3. Add 80 grams of citric acid;
4. Soak your oversized copper SPP for 12 to 24 hours in this mix;
5. Take out the SPP, rinse it with water, and put it under 45% strong alcohol.

*) When copper rust increases the total surface area in the column, there's less space for the rising gasses to travel up. Vapour speed will increase, further increasing the chance of copper particle contamination. **) Especially in Pure Mode, the iStills 50 and 250 manage the reflux vs. take-off rates, in order to continuously give you 96.5%. Severe copper rusting, due to the increase of surface area, prevents the return of refluxing water and tailsy alcohols to the boiler, and can create column flooding.