Cutting paint is a dirty process and produces plenty of rubbish, exhausted product plus removed clear coat. The pad will simply not cut correctly, if it is contaminated. It is therefore imperative that whenever new product is added to the pad, that the pad is first cleaned with a correctly designed pad brush (3M). In other words whenever you put the polisher down after completing a sectional pass, the pad should be cleaned to remove all the spent material. This step should apply when using any polish, but especially when using a compound such as M105 which produces so much spent material. As you are new to polishing, I suggest that you get in the habit of cleaning the pad whenever you down your polisher, each and every time. If you learn that way, it becomes an ingrained natural habit.
As an aside, there are many threads here about a pad brush ruining a pad. In all instances, I would have to conclude, if that is happening, it is because of user error. A pad brush is designed to clean foam pads, so obviously if the pad is being damaged by the brush then the user must be using it incorrectly. The brush only needs to be lightly applied to the pad and then drawn across the pad to be effective. Obviously your DA should be on either speed 1 or 2 (depending on the DA) for pad cleaning purposes.
I suspect because many people don’t work clean, that those who have damaged a pad have left it far too late before attempting to clean the pad and therefore when they do attempt to clean the pad, they dig the brush into the pad trying to clean it and so damage the pad. If such a pad is so gummed up with spent product, then it should have been changed out for a new pad well before that point.
Two final points, tooth brushes are for cleaning your teeth, not foam pads. I personally think trying to clean a pad with an MF is a total waste of time when compared to the correct use of an inexpensive properly designed pad brush.
