So you have a little ding on your bumper that you want to repair, and you're not quite sure how to prepare your car for a proper blend. This is really common, they can really save you a lot of money considering that most auto body shops will charge you $6-$800 just to fix a simple scratch on your bumper. Of course you will need to have a little bit of equipment, and perhaps you have the ability to borrow it? That being the case here is how you prepare your car in order to do a proper blend.
The first thing that you should do is take off the surrounding area. Let's assume that you're going to be repairing the bumper, you will then want to make sure that you take off everything about the bumper and make sure that you have some paper about the tape so you don't get any over spray on the car. You will then want to clean the car with a very strong solution. We used to use a reducer of some sort, but feel free to use acetone. What you're really trying to accomplish is getting any contaminants off of the bumper so that your clear won't fisheye. Then you will take some sandpaper and sand off the offending scratch down to the plastic if necessary, and then filter out the sanding to match the existing paint.
That's really all there is to prepare and car for a proper blend. You basically just want to make sure that you sand off the offending scratch, and then make doubly sure that the car is especially clean. You would do this by using a strong chemical such as acetone, or some sort of paint that are necessary. Contaminants are your worst enemy whenever you are trying to paint a car. The next thing you will want to do is to paint the spot that you just sanded, making sure that you feather the edges using a sweeping motion with your wrist and not getting the paint too heavy in the middle. After the paint dries, you can then clear it making sure that you blend the edges. This should make a nice job for you, and if done properly will ever be able to tell your bumper was in first place.
