Differences in the same laundry

Winter wash result comparison

Tekno Forest report on a major comparison of winter washing results. Does a normal car wash remove road salt and other winter dirt types. In the test, six metal plates were attached to the side of the car and the car was driven along a salted motorway.

Big differences in the final wash result in laundries of the same chain

In winter 2018, Tekno Forest, a car wash chemicals company based in Rihimäkelä, found out why the persistent dirt on car sides did not come off in a normal wash. In the test, six metal plates were attached to the side of the car and the car was driven along a salted motorway. 

1. Half of the plates were taken indoors for two days to dry, three plates were left outside.

4. The car was washed three times at each car wash and each time there was a different level of dirt on the side of the car.

2. The test used three reference plates as comparators, on which an asphalt bitumen membrane was sprayed. These sheets were also left outside for two days to dry.

5. The temperatures of the plates were measured before washing to ensure that the conditions were exactly the same.

3. After the dirt had dried outside on the plates for a couple of days, the car was driven to three different automatic car washes in the same chain.

6. For each laundry, the same name was chosen, and the most expensive laundry option was selected.

Surprising differences in washing results

Although the laundries in question were from the same chain, the results differed considerably between them. Fresh salt pork was well cleaned in all three laundries. In contrast, dried dirt remained almost in place at two of the three stations. At these two stations, the cleanliness of the sprayed plates also left something to be desired.

Tomi Pohjolainen from Tekno-Forest, who develops detergents, explains the differences by the fact that the stations use different detergents. Not all detergents are suitable for winter use, even though the chain and the washing programme purchased are nominally the same.

Laundries may also have different types of machines. But the dirt itself is the same as it always was - salt and bitumen scraped off the asphalt by a studded tyre.

Pohjolainen sees a structural problem within the industry: there is no quality standard that would force the stations to adjust the chemicals in their washing machines and meet an agreed quality level. This is particularly acute when a fixed-price contract between the service company or entrepreneur and the chemical supplier is applied. Detergents or concentrations are not changed from one season to another, as environmentally friendly detergents are more expensive. This makes it tempting to save on concentration, even though modern washing machines allow different amounts of detergent to be dispensed in different areas of the car.

A hand pre-wash ensures a better wash result.