The first mistake many people make when cleaning their car is not to pre-wash. This leaves damage inevitable as so much grit and large particles of dirt are sat on the car when you start. Pre-washing involves ridding the car of dirt and other loose pollutant chemicals from the paint surfaces before you carry out a hand wash on the car. It softens dirt and surrounds the larger particles drawing these away from the surface of the paintwork and wheels. This includes traffic film, grit, bugs and bird droppings.
Pre washing is a must to help keep the infliction of swirl marks, scratches and abrasions to an absolute minimum. The key is to remove as much dirt as you can before actually touching the car.
A pre-wash rinse can start the softening process. Using a pressure washer or hose work from the top down, rinsing the panels carefully. Pay particular attention to panel gaps and regions, which may trap dirt (inside roof rails for example) and rinse these out thoroughly. If you do not have access to a hose or pressure washer, grab a watering can and put the rose on it and use this to rinse the car as thoroughly as possible. You want to focus on removing as much loose dirt as you can from the bodywork and gaps including the wheel wells so that it doesn’t get caught in your wash later on.
Alternatively use a pre-wash foam, often called snow foam. This involves covering your car with a film of foam using a foam lance connected to your pressure washer. An alternative is to apply shampoo through a garden sprayer type bottle. There is significant discussion on the benefits of snow foaming but I have found that it definitely eases the next stages of the process.
Snow Foam is dedicated to the purpose of being on the car and softening dirt, car shampoo isn’t. Car shampoos can also tend to dry out and leave marks on the bodywork and windows which will need more work later on to remove. In addition Snow Foam generally costs less than a good quality car shampoo.
The theory of snow foam soap lies in its reaction with grease, grime, and dirt. A dirty car is covered in particles, some stuck tightly to the surface. Soaping and scrubbing the car risks dragging or digging these particles into the body work of your car. The foaming soap clings to the surface and helps to lift the particles off of the surface thanks to its cleaning power. When you rinse the foam off, there will be significantly less grit on the exterior, so you don’t have to worry as much about putting scratches in while washing. As the foam gently breaks down dirt and debris, your wash is much less abrasive and hence scratch free.
When applying snow foam to the car do it methodically panel by panel like painting a wall. You don’t need to repeat applications over the same area. Start on one side and apply from the roof down with unhurried sweeping motions of the lance either side to side or up and down.
You can leave the car to soak for around 5 to 10 minutes depending on the weather at the time and then do a final rinse with the pressure washer or hose before starting with your shampoo. Remember to avoid putting the pressure jet too close to the paintwork – about 1 metre should be fine. Also don’t use high-pressure setting as this could drive dirt into the paint causing scratching.
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