What causes spider webs in auto paint?

Answer 1

Everything. Dust, rags, car washes, there is absolutely no avoiding the spider web effect which is most noticeable on black surfaces. Clear coat which is the top layer of urethane paint on your car remains somewhat soft even when completely cured what this means in tiny particles of dirt and sand and even rough spots on a rag when you're washing your car can help to create swirl marks, the only way to remove them is the remove a small amount of the clear coat layer and in essence make the surface flat again.

Depdending on the severity to remove sand scratches (swirl marks) from a paint finish you should first sand the surface with a 1500 grit dual action sander with DRY paper. It is also possible to perform this process by "wet sanding" however it takes much longer to yield the same results. From there you CAN use a rubbing compound on the surface (best when applied with an electric buffer at 1500 rpms). However the fastest method is to then further refine the surface using a 3000 grit sandpaper, 3M has a series of sandpapers called Trizac which are made specifically for this purpose. After thoroughly compounding (several times if 3000 grit paper is not used first) then a swirl remover should be used followed by a finishing glaze. 3M has a phenomenal product line that does exactly this. Basically if you think of compound as an abrasive comparable to sandpaper (it will remove paint, but very slowly) then the compounding stage following sanding should follow similar steps as sanding, rubbing compound is your "standard" grit, swirl remover is your "fine" grit and the final glazing step is your "ultrafine". The proper compounds do NOT fill scratches, they eliminate them by very finely removing the top layer of clear coat.