Washing a on a rainy day?

In Japan, we are in the middle of summer and it has been hot! Extremely hot! I know it is not going to change the situation even if I say it a hundred times but when I see someone I cannot help but saying “It’s hot, isn’t it?” as a greeting. It is like our custom to use weather as a part of greeting, isn’t it?

When we hand over a car in our yard to the customer, we wash it beforehand but when it is this hot, washing a car seems a really hard job. If it is a mini car or compact car like Vitz and Fiat, it does not take that long, but if it is a mini van or a wagon, the area for washing is large so we will be sweating like a pig by the time we finish it. We wash outside first, then clean inside and it is hard not to drop any sweat on the seats in case they leave marks on the upholstery. But I guess it is the same situation for every car dealer. So we try not to think about it too much and get on the job thinking that it can solve the problem of our lack of exercise.

The other day, I had a special order of a Porshe Cayenne so our usual cleaner came to clean inside and I was to apply a polymer coat outside. While we were working, I said to him “I get disappointed if it rains just after I wash a car” but he said “It is not always bad to have a rain straight after we wash a car”.

According to him, the reason is to do with acid rain & ultraviolet rays. Quite often, when we wash a dust covered car after a rain, we cannot totally get rid of the grime and water stains easily. This is something to do with “oxidization”. If we wash a car soon after it gets dirty, it is easy to get rid of the dirt but when the dust and dirt get oxidized, it gets hard to get rid of. The reason for the oxidization is the dust and dirt change into an oxidative product after some chemical reactions among the “dirt”, “rain”, “ultraviolet rays” and “heat”. Also when an oxidative product touches acid substances it gets more oxidized called “resonance oxidization”. If we wash a car when the dust is only on the surface of it, we can get rid of it just with water but when acid rain touches the dust it turns into dust that is hard to get rid of. It also oxidize the paint, coating and wax on the surface, causing dullness.

Ultraviolet rays on a fine day can also cause damage to the paint. When the dust which turned into an oxidative product by acid rain gets ultraviolet rays and activates more of the oxidation reaction and gives more damage to the car’s body. However, we cannot really stop ultraviolet rays reaching our cars, so it is important not to leave dust and dirt on the cars too long.

Lastly there is “solar heat”. When the sun heats up the surface of a car, it causes microscopic holes just like pores on human faces. If you wash a car then, water and detergent get into the holes and makes the paint look dull. Water dries out quickly on a sunny day and if you try to get rid of dried dirt with sponge or towel, it also scratches the surface.

In this way, when the sun hits dust and dirt on a car which is already oxidized, oxidization by ultraviolet rays occurs and leaves some dirt and scratches on a car. It is important to wash your car before it rains.

Although I understand his theory, I am not keen on handing over a wet car just being in the rain. It means I would have to wash it again after the rain, which means it would take twice as long to clean a car.


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(Editor)
JPC TRADE CO.,LTD.
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