It is not always required that you use this product(s) before staining. It depends on the type of wood and its condition. As well as the type of stain you will be applying to the wood.
You can test your wood to see if it will readily accept stain by sprinkling the surface with water. If the water absorbs quickly into the wood, it is likely that the wood will also accept stain. This is so if you are using a stain that is compatible with the new wood application. Check if the water stands on the surface or beads up when you sprinkle water on the wood. If so, we recommended that you go through the cleaning and brightening process before applying a stain. It is also a good idea to use the cleaner and brightener. That is if you believe your new wood has been outside long enough to be exposed to pollen. Pollen is an excellent food source for mold and mildew.
Finally, if your new wood has been outside long enough to begin turning grey, it is recommended that you use the cleaner and brightener to remove the dead grey wood fibers on the surface. So that your stain finishes evenly and without splotches.