Coffee 101: What is Descaling?

Beginner’s Guide To Descaling An Espresso Machine

The most common cause of espresso machine failure whether in a commercial or residential machine is “scale.” If you’re looking to have your espresso machine around for a long time and cut down on maintenance costs, then you should at least descale it. The process will not take you more than a couple of minutes per month.

What is Scale?

Water, especially hard water, has elevated levels of magnesium and calcium salts, which are essential for nutrition. However, when you heat up the water in your espresso machine, the salts precipitate forming lime-scale, which affects the innards of your machine negatively, especially your boiler.

How Does Scale Build Up?

Once you turn on the steam, the heating component is activated and it heats the boiler to temperatures above the boiling point. At this point, all the minerals that are dissolved in the water start precipitating and end up coating the insides of your espresso machine, which causes scale.
Ultimately, scale builds up and begins to clog the narrow steam channels, the innards of your machine, and the heating components.

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Why You Should Care About Scale

Over time, as lime scale builds up it will disrupt the flow of water, cause problems with heating, and significantly reduce the capacity of your boiler. This eventually leads to blockages. This will, in turn, reduce your coffee output and produce a lot of noise because your pump is overworked.

Additionally, because of the scale deposits in your machine, water won’t be able to be in direct contact with your boiler which leads to inconsistent coffee temperature.

Furthermore, the golden-brown layer on the surface of your coffee-crema will become thinner over time. The flakes of lime scale will wash out of the espresso machine and may seep into your drink. Since these flakes have a high concentration of minerals, they will certainly ruin the taste in your cup of coffee.

Descaling Your Espresso Machine with a Descaling Solution

Descaling is a process that essentially uses an acid solution to dissolve the mineral deposits and wash the solution away. You will need three things when descaling your espresso machine: a descaling solution, a blind filter, and liquid receptacle.

You can get descaling solutions in liquid or powder form. Some home-made solutions like vinegar or lemon juice could work, however, most agree that vinegar is not suitable and as for lemon juice, you don’t want to be stuck figuring out how to remove the seeds from your boiler.

Most espresso machines come with specified descaling solutions, which we recommend you use, but if you have a manual machine and the manufacturer hasn’t specified any solution, then proprietary solution like Urnex and Durgol are excellent choices.

How to Descale an Espresso Machine

Most manufacturers provide a detailed instruction on descaling, but if you can’t find yours, here is how the process generally works. You basically fill your machine boiler, let the solution work its’ magic for about 15-20 minutes and replace by having it run out of your steam wand under pressure.

Repeat the procedure for 3-5 times until you have used up about a liter of your descaler and then flush it out with water until all the bad taste disappears. It is that simple.

Having said that, you should exercise care while descaling your machine especially if you’ve neglected it for a long time. This is because a huge amount of scale deposits could potentially block your valves or gauges if not done properly. Additionally, as you know electricity and water are a combination to be handled cautiously. Be careful to not electrocute yourself in the process.

Espresso Machine Descaler Solutions

Note: Not every espresso machine can be descaled at home by yourself (like an espresso machine with heat exchange), so make sure to check the manual on this matter. Some espresso machines need to be professionally descaled.

For the machines that can be descaled at home, there are some manufacturers which recommend a specific descaling solution for their espresso machines. However, when there is no specific product mentioned, you can use any of the widely available espresso machine descaler solutions. Just make sure you check if it needs to be based on citric-acid or lactic acid for example. The most recommended espresso machine descaler solutions are:
Durgol Swiss Espresso Descaler
Urnex Liquid Dezcal Activated Descaler

Resources

Seattle Coffee Gear, how to descale
Coffee crew on descaling
1ste Line Equipment, descaling a heat exchanger coffee machine
Talk Coffee Australia, should I descale?
Philips Saeco descaling