Cleaning Chillers

Copper has some excellent properties that make it great for brew kettles and wort chillers. Copper is a superb conductor of heat and is highly malleable, which means that it can be easily formed for use where thermal conductivity is important. Copper is not pure and contains a small amount of zinc. It’s also soft and does dissolve over time, which means that copper contributes copper and zinc to wort. Zinc is a micronutrient and is beneficial to yeast growth and metabolism and copper binds sulfur formed in fermentation.

The downside to copper is that it is soft and dissolves over time, even when it is treated with great care. This is why old copper kettles eventually wear out. Many breweries with copper kettles and mash mixers replace the copper bottoms with stainless steel because copper is expensive and not easily repaired, especially as the number of skilled coppersmiths continues to decline. These breweries use specialty cleaning chemicals containing corrosion inhibitors so that strong alkaline cleaners, principally sodium hydroxide, can be used for cleaning. Acid cleaners are also commonly used to clean copper.

You can certainly clean your copper wort cooler with mild dishwashing detergents and a gentle scrubbing pad. Mild abrasives can also be used on copper. Some commercial breweries use a diatomaceous earth (DE) and yeast residue removed from filters to clean copper. The DE is a fine, very abrasive, similar in texture to the perlite (volcanic ash) used in toothpaste, and the yeast and residual beer is mildly acidic. This stuff really works well and is a nice way of turning a waste product into a handy cleaner.

Oxalic acid cleaning powders, such as Bar Keepers Friend, are very effective metal cleaners when used as a paste. Simply cover the copper coil with a mixture of oxalic acid powder and water made up to a thickness of hand lotion, allow the mixture to sit on the surface for about five minutes, wipe with a soft towel to gently scrub and rinse well with water. If your coil is too tight you may want to consider opening it up a bit to permit easier cleaning, or use a soft brush to help get into the small gaps of the coil.

As a side note, oxalic acid powders also work very well to clean stainless steel. Care must be taken when cleaning polished stainless with any type of abrasive because the surface appearance is easy to change. Also, polish in the direction of the grain.

I would stay away from the dishwasher unless you really know about the detergent you are using. Many dishwashing detergents use chlorine bleach to help remove proteins, and chlorine pits copper. Some dishwashing detergents contain alkaline components that can also damage copper. The thing about most household cleaners is that it is very difficult to know all of the stuff contained since the blends are proprietary. Another thing to consider is that no manufacturer of copper cookware recommends washing in a dishwasher because of the potential damage that can occur. That’s a pretty good reason to avoid the dishwasher!

Perhaps one of the handiest features of copper immersion chillers is that the entire coil can be boiled prior to use. Dr. Michael J. Lewis, the famed UC-Davis brewing guru and my mentor, is known for his wit and oftentimes blunt descriptions. “You can sterilize dog s—t, but that does not make it clean.” This was Dr. Lewis’ explanation of the efficacy of heat sanitation. So even if your copper wort chiller is not immaculately cleaned, immersing the coil in boiling wort for 20 minutes or more will kill any microorganisms on the surface.

 

Response by Ashton Lewis.