The secret is to go slowly, think what you are doing, keep any repaired area as small as possible and cut back the paint edges with W&D paper and cutting compound at each stage. This removes over-spray from primer, colour coat and clear coat.
As an example, lets take a repair the size of a £2 coin. You flat the damage out using say P240 which leaves tapered paint which reveals a quarter inch of primer around the coin shape. You then wet flat with P800 W&D to remove the P240 scratches. Wash down the rubbing residue and ensure you have a clean area about a foot back all round the repair. Dry the worked area and the surrounding existing paint. Spray three coats of primer at fifteen minute intervals. The primer should cover the damaged area and extend all around by about an inch. Let dry for 24hrs to harden.
Next day, just dust coat the primer with a pass from a can of matt black spray paint. That is just a mist of contrasting colour over the primer and is known as a guide coat. Wet flat the primer and guide coat until the guide coat has been rubbed off. The guide coat sits on top of the primer and also in the orange peel effect of the sprayed primer. Rubbing down with P1200 W&D until the guide coat disappears and the primer is flat, gives the good surface finish needed for top coat. Use the P1200 to remove excess primer and dust over-spray. Polish up the primer with cutting compound and cut back the excess primer to keep the repair as small and tight as possible. Yes, you will take off a few molecules of existing clear coat in the process.
Having cleaned up the excess compound and wishy washy general residue, wash and dry the part finished repair. Now spray on three coats of colour coat at fifteen minute intervals. Ensure you run an inch over the edges of the new primer. Step away from the job for 24hrs.
Next day, gently flat the colour coat with P1200 W&D paper. Go easy and flat off the edges of the colour coat to remove dust edges and blend into the surrounding paint work. You can cut back and polish the new paint with cutting compound to remove any flatness. Wash, clean and dry again. Then spray three or perhaps four coats of clear coat on the job and again walk away for another 24hrs.
Next day, flat down the clear coat with P1200 W&D. Polish up with rubbing compound and blend in the colour coat dust edges. This will finally give you a repaired job. Finish off with your favourite car wax.
Most people don`t know how to use W&D paper. Place a new sheet in front of you. It is A4 paper size. Fold the paper in half length-wise. Effectively you have two long strips. Fold back and forth a few times, then tear the sheet down the fold line to get those two strips. Take a long strip and fold in half, top to bottom. Open out and fold the bottom of the paper to the crease line you have created. Then repeat again with the other part of the paper above the crease line. What you are trying to achieve is to make four small working surfaces which you can open out change the worn surface to a fresh one as the abrasive wears due to use. You are trying to create a paper area that fits nicely onto your hand. One corner gets gripped between your thumb and forefinger.
These images may help you with this basic origami. I`ve used a sheet of white paper to show the folding technique. In use do not allow any of the abrasive surfaces to touch one and other. That will rub the two surfaces to extinction and wear the paper out in double quick time. Use the paper FLAT in the palm of your hand and DO NOT rub with your finger tips. That would put tramlines in your work!
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