The two-bucket method is possibly to most known and most used technique used by detailers and professionals, to wash a vehicle. It is one of 3 different types of washing a vehicle that are widely considered to be safe and correct ways of cleaning a surface.
What is the 2-bucket method
The two bucket method revolves around using 2 buckets to wash a vehicle. 1 bucket is filled with a shampoo/water solution, the other bucket is filled with clean water. The tool that is being used to wash the surface (washmitt, sponge etc.) is submerged into the bucket with the water/shampoo solution and used to wash the surface. When you are done, you rinse out the used tool in the bucket with clean water. When the tool is clean again, it can be submerged in the bucket with water/shampoo solution again to wash the next area.
Why use the two bucket method
If you would skip the rinsing step, the dirty tool (after washing the surface) will make the water/shampoo mixture dirty. The dirt it picked up will now be in the water. The next time to put that piece of equipment in the bucket, it will not only contain water with shampoo, but it will also contain small particles of dust and dirt. The longer you keep doing this, the more dirty the water will get. The more dirty the water is, the more dirty your tool is getting. Eventually you will be washing the surface with dirty water. Which can cause swirls and other surface imperfections.
To minimize the risk of swirls or other surface imperfections, it is important to rinse out the tool you are using. Only if it is really clean, it can move safely over the surface without scraping the dust and dirt over the surface. After having spend many hours polishing a vehicle, trying to make it look as perfect as possible, you don’t wanna create the swirls you jut removed.