A sponge with grip will help you clean the roof easily.
We recommend you use an absorbent microfiber towel instead of a normal towel, because it doesn't take as much effort and time.
1.Prepare Car Shampoo
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Lather Well.
Car shampoo removes dirt, floating it with soap like hair shampoo and face cleanser.
Lather well to remove dirt easily. 
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Pour Water Vigorously!
Pour the car shampoo in the quantity indicated on its bottle into an empty bucket and pour water vigorously. This is how to make a good lather.
When you use a hose, it's a good idea to adjust the hose nozzle to a narrow pattern.
Make sure of the quantity indicated on the bottle before use, because it varies depending on the car shampoo. 
Tips
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For some car shampoo, it's better to apply the liquid directly to a sponge.
Some car shampoo works more efficiently when the liquid is applied directly to a wet sponge.
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- No-Need-To-Be-Diluted Car Shampoos
2.Wash Tires & Body
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Start From Tires.
Wash the dirtiest parts, tires and wheels first. If these parts are washed later, mud and dirt may come in contact with the car body which you just cleaned.
Rinse to remove mud and sand roughly, and wash using a sponge with a car shampoo. Be sure to rinse thoroughly afterward. 
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Tips
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Use A Separate Sponge On The Bottom!
Sponges used for washing tires and wheels are clogged with tiny mud clots and brake dust. If you use the sponge for washing the car body, it will leave scratches on the body. We recommend you buy different color sponges or use old sponges for tires and wheels in order to be sure to use a separate one.
- Wash mitts for washing wheels are convenient!
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Wash Body.
Washing the car body where dust and dirt still remain leaves scratches on the surfaces.
Rinse off dirt from top downward (Roof→Windows→Hood→Trunk→Side Body→Bumper). -
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Do Not Scrub.
Scraping dirt off causes scratches, so rinse it with water. Dirt will be easily removed if you bring the hose close to the dirt and flush it vigorously.
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Tips
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Prevent the hose from coming in contact with the car body.
If the hose comes in contact with the car body, it may cause scratches. Especially be careful when you rinse a farther part on the roof and hood.
3.Wash With Car Shampoo
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Wash Gently.
Allow the soap and car shampoo liquid to be absorbed into the sponge, and wash gently.
Scrubbing aggressively causes scratches, however, you can scrub difficult dirt like water stains. A sponge with a grip will help you clean hard-to-reach areas. 
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Wash top downward section by section.
Rinse thoroughly before dirt risen with car shampoo adheres to the surface again.
We recommend you wash and rinse per panel especially during the summer or in high temperatures. -
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Tips
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Use Old Toothbrush!
Apply the car shampoo to a toothbrush and scrub dirt on narrow gaps and the area where sponge can't touch.
Be sure not to scrub too aggressively to avoid scratches.
4.Dry With A Towel
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High Absorption Towel Helps You A Lot!
This kind of towel can absorb many times as much water as a normal towel, which allows you to finish drying in no time at all.
There are various types and sizes such as towels, sponges, etc. Check them out at your nearest stores. -
Wiping Technique.
Spread the towel on a wet car body and pull it toward you. It allows you to efficiently dry the car with a towel, especially the hood, roof, etc.
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Tips
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Dry Thoroughly! Do Not Leave Water Drops Behind.
Especially be careful During high temperature and dry seasons. If calcium and chlorine contained in tap water dry in a short time, it becomes a mineral deposit, which a regular car wash cannot remove.
