Why does the cold wash cycle take shorter time?

Washing at 60 degrees takes two hours; Washing at 30 degrees takes 10 minutes less. Makes sense, if you look at the water heating time. But shouldn't you wash longer at 30 degrees?

There has been scholarly writing about literally everything. Likewise in “The Effect of Washing Cycle Time, Temperature, and Detergent Composition on the Hygienic Effectiveness of Domestic Laundry” (Journal of Applied Microbiology2014).

At lower temperatures, a longer wash cycle is generally needed to get laundry evenly clean, this article concludes. But the detergents used are also important. Detergents containing “Active Oxygen Bleach” also clean laundry quickly at low temperatures Applied environmental microbiology (2021), but it often contains chlorine: it is not very environmentally friendly.

Optimal balance

Ask the manufacturer of the Miele machine. “The effectiveness of washing is determined by the so-called fault circuit,” says organization spokesman Martin Bos. “It includes four factors: temperature, time, chemistry (i.e. detergent) and motion. A clean wash result requires an optimal balance between these factors. If you adjust one of them, it may affect the wash result.

But how exactly is this done? “It depends, among other things, on the washing programme, technology, heating element, detergent, etc.” However, eco programs (programs that use less energy and water) often take longer than regular wash programmes. Compare that to driving 100 on the highway instead of 130, Boss says: “Then you drive more economically, but you also get to your final destination. It just takes a little longer.”

But what about non-eco programs, which last shorter at lower temperatures? “Each manufacturer has its own way of balancing these four factors,” says Olivier Boss of Electrolux/AEG. “We use different techniques to compensate for low temperatures. For example, mixing water with the detergent before it reaches the clothes. And an innovative dilution pattern in the drum, which ensures optimal water distribution with the least possible pressure on the clothing fibres.

Too short or too long?

Okay, but this all works at all temperatures. Why wash for a shorter time at a lower temperature? This is partly due to the warm-up time. Boss: “With the same program, in the same machine, heating to 60 degrees takes about 20 minutes longer than heating to 30 degrees.” But then you actually wash the wash at 60 degrees for a very long time. Because while heating, the machine also washes clothes for a period of time at temperatures of 30, 40 and 50 degrees. Or was the normal wash at 30 degrees too short? No, says Boss, and neither: “If your laundry is moderately dirty, you don't really need a higher temperature. You choose the temperature partly depending on how dirty it is.”

This is also what our namesake Boss Van Meele says: “It depends on what you wash. A perfectly clean wash result is always our starting point.” He adds that nowadays this works best with a digital laundry assistant and automatic detergent dosing. This has made it Easier and more economical.

What does science say? He says that more microorganisms survive at 30 degrees than at 60 degrees, all other things being equal Applied microbiology Simply. But for pathogens, e.g Staphylococcus“It doesn't matter,” he said Journal of Infectious Diseases.

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