What you should know about Espresso Machine boiler

By Sergio Louissaint

August 15, 2009

An espresso machine boiler is the most important component of an espresso machine. It's where the magic happens. It's where much of the process of coffee making happens and therefore, it's important to keep espresso machine boilers in good condition.
On the surface, espresso machine boilers appear to be very solid and durable because they're made out of metal which we are often told is durable. Yes, metals CAN be durable but without the proper maintenance, metals are anything but durable. This is due to the fact that metals tend to be chemically reactive to various substances in the enviornment, like salt water and oxygen and chloride. The process of metals chemically reacting to various substances is called corrosion.
Manufacturers have gone to some lengths to delay corrosion in metals that espresso machine boilers are made from. They have also presented consumers with an array of choices. Metals that constitute espresso machine boilers include stainless steel, aluminum and copper/brass. Some of these choices are good for consumers, some of them aren't.
Even with all the precautions that manufactures take, the artificial human environment can do just as much damage to metals as nature, if not more. This is because the human environment allows for chemicals that don't often come in contact with each other in nature to come in contact with each other. In addition to that,coffee boilers are subjected to high temperatures which speed up chemical reactions that may be occuring. Temperatures as low as 257 degrees are enough for heat related corrosion to occur.

One of the metals that espresso machine boilers are made from is aluminum. Aluminum is protected from corrosion by increasing the amount of naturally occurring aluminum oxide(Aluminum+Oxygen) on its surface. The oxide serves as an alloy and under ideal circumstances,it protects the aluminum for a long time but all it takes is for a catalyst, sa substance to speed up the the process of the aluminum oxide coating's breakdown, for aluminum to begin to corrode.
The small amount of chloride present in tap water can cause damage over time, forming small holes called pits. Using filtered water may help but is no garantee.

There's come controversy stemming from allegations that aluminum may cause dementia. Fortunately, there is no proof that aluminum causes dementia in anyone but people with kidney failure. Kidney failure prevents the human body from purging the small amounts of aluminum that enter the body from tap water and other sources. It's nothing to be worried about if one's kidneys are fine.
Aluminum boilers may be at a lower price point than espresso machine boilers made from other metals but they require some knowledge of chemistry for maintenance. They're a good investment for the obssesive-compulsive individual.

Stainless steel coffee boilers are very corrosion resistant because steel is a very effective alloy but--steel can host bacteria for a long period of time on its surface. This may seem like a departure from what has been discussed so far, but since culinary sanitation is a large concern for those who prepare or deal with food.
Even if someone doesn't cook they probably have had food poisoning at some point in their lives due to a lack of food sanitation. Sanitation is something that affects everyone. Research within the last ten years may make manufacturers consider changing steel's widespread use in medical and culinary settings.

The research conducted in the last ten years proved that steel was bacteria friendly, has uncovered that brass, an alloy made of copper and zinc, inhibits growth of bacteria. This property is attributed to copper. The bacteria actually need copper as a mineral to survive but suffer from some kind of copper poisoning; there's too much copper for their "copper pumps" to metabolize. Overwhelmed, many of them die as result.
Copper was used as an antiseptic in the form of splinters or fine grains thousand of years ago by the Romans, Egyptians and Aztecs among others. It's only in the last ten years that humanity is only beginning to rediscover the antiseptic qualities of copper and copper alloys, such as brass.
In addition to antiseptic properties, brass is much more corrosion resistant than other metals. Copper does react with oxygen in the air to form a blue to black layer called copper carbonate that actually protects copper from further corrosion.

The Statue of Liberty is covered in carbon carbonate and it's not going to fall apart due to corrosion.
If you're considering a new espresso machine then you'll be pleased to know that Lelit is one of the very few espresso machine manufacturers have brass boilers in as part of their espresso machines. Their machines will last longer will require slightly less maintenance, and are more sanitary when it comes to their boilers.

To Life, health, and longevity,

Sergio Louissaint, LatteMaestro Contributor

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