Which Distillation Still is More Appealing: Copper or Stainless Steel?

Which Distillation Still is More Appealing: Copper or Stainless Steel?

In the beginning

The earliest evidence of distillation technology seems to date back to around 2000, whereas evidence for alcohol fermentation predates it by about 7,000 years! So, it’s safe to say that alcohol consumption has been a part of human experience for a long time. It makes sense, as fermentation occurs naturally without human intervention.

Is it possible that ancient and hungry travelers would stumble upon free fallen fruits under a fruit tree? Only to find that the fruits had become overripe. In ancient times, hungry travelers might not have many options, and it was better to eat overripe fruit for dinner than to go hungry.

By the way, distillation also occurs naturally through evaporation. If we consider precipitation, the entire planet is a distillation apparatus.

Distillation is essentially a process of mass transfer and phase change. Humanity has discovered a way to exploit this naturally occurring phenomenon through forced propagation techniques.

Enter the Bronze Age

Since copper is the oldest known metal, dating back 10,000 years, it is reasonable to consider it as a potential material for various vessels after stone, clay, and wooden pottery. Ancient copper containers were used to store food and water to prevent the growth of pathogens. No wonder copper pipes are commonly used in modern plumbing systems. Furthermore, copper was used in sailboat hulls to prevent barnacles from attaching.

Copper is also highly conductive, with a conductivity ratio of 97 out of 100. Silver represents 100 and gold represents 76. Copper is an amazing material with versatile properties. Luckily, copper is also very malleable, making it ideal for crafting tools and containers, including those for liquids.

When it comes to distillation, copper has the extraordinary ability to remove sulfides produced during beer or wine fermentation. This makes copper the material of choice for stills. Exposing fermented beverages to copper during distillation helps reduce the undesirable rotten egg smell and leads to a better final product. Many experts believe that modern brewers rely too heavily on copper, potentially neglecting the fermentation process compared to their beer brewing counterparts. This is a topic for further discussion.

Considering all these factors, copper has become the de facto material for winemaking equipment. It is easy to use, possesses antimicrobial properties, and helps mitigate negative odors and flavors resulting from suboptimal fermentation processes.

ACE 500L copper distillation equipment

Fast Forward

The origins of stainless steel can be traced back to the early 1800s when chromium was discovered to resist strong acids. In 1861, Robert Forester Mushet filed a patent for chrome steel in England. Throughout the 19th and early 20th centuries, there was a race to exploit the commercial potential of this corrosion-resistant metal. By the 1950s and 1960s, stainless steel production technology had advanced to the point where large quantities could be produced economically. Today, there are over 150 grades of stainless steel, with 15 being the most commonly used. In the United States, approximately 90% of ethanol refineries use 304 stainless steel.

In the food and beverage industry, 304 and 316 stainless steels are the most widely used because they do not affect the taste of the final product and are easy to clean and sanitize. Therefore, stainless steel seems like a suitable material for winemaking environments.

However, stainless steel reacts differently to beer or wine compared to copper. Although stainless steel is easier to clean, sterilize, and more resistant to weak acids than copper, it lacks the ability to remove sulfides like copper does.

How much is too much?

The good news is that you can’t have too much copper in the vapor path of your distillation equipment. Unless you have precise control over your fermentation process and are an expert distiller, adding copper to the steam path of your distillation equipment is necessary. However, copper has become expensive, so the question often becomes how much copper can be used in the steam path?

At ACE, we have found a balance by using a significant amount of copper in the system while incorporating stainless steel for its advantages.

We can certainly build a still that is 100% pure copper. But there are more affordable and objectively better options available.

At ACE, we believe that copper exhibits the best reactivity when in contact with suspended steam. This means that when the alcoholic liquid becomes hot enough to produce vapor, and the pressure forces the vapor through the distillation circuit, exposing it to the copper surface will yield the best results. While the alcoholic solution benefits from contacting the floor and walls of a copper kettle, we believe the greatest benefit is achieved when the steam comes into direct contact with copper.

Some modern systems are made entirely of stainless steel but incorporate a copper catalyst somewhere in the steam path, typically at the top of the distillation column. The hot vapor passes through the copper catalyst before entering the product condenser.

Using copper during the distillation of spirits undoubtedly improves the quality of the final product. The real debate lies in determining how much copper is truly necessary. Can you have too much copper in the vapor path of your distillation equipment? The consensus is that too much copper is never harmful, while not having enough copper can be detrimental.

How much copper is needed in the steam path remains a subject of ongoing debate.

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