Some stains are more easily removed with a pre-treatment; but first ensure that the chosen cleaner does not have a negative effect on the material i.e. does not cause colour change. Read the product labels and manufacturers safety data sheets (MSDS) to obtain a basic idea of contents, pH levels etc.
There are two basic approaches to removing spots and stains. You can use a stain-removal agent that interacts with the stain chemically, or you can physically loosen or remove the stain from the surface. Many stubborn stains require both chemical and physical treatment.
Brushing is used to remove dried stains and spots. Flushing is used to remove loosened staining materials and any residue from the stain-removal agent. This is an important step in the process, for if any chemicals are left in the material, they may cause additional staining or they may damage the treated article.
Pre-treating is used to ease the removal of small stains, especially those that are oily or greasy. Stubborn soil is easier to remove after it's been pre-treated.
Depending on the pH of the product you use you should return the surface to neutral (pH 7.0) before you apply any dressing or protective products. The correct philosophy regarding chemical use is this: “only use chemicals for what they were formulated for”.
Always select a chemical / cleaner that are biodegradable, environmentally friendly and safe to use by observing any precautions recommended so that they won’t harm you, your vehicle or the environment. Read the product labels and manufacturers safety data sheets (MSDS) to obtain a basic idea of contents, pH levels etc.