Various factors must be taken into account. First of all, it depends on what is to be covered. Has the surface to be sprayed on been painted before? Is it a plastic that is to be sprayed? etc. etc. The substrate should always be pigmented higher than the subsequent paint. Primers are highly pigmented; clear coats do not contain any colour pigments. The optimal structure is therefore primer "Buntlack" clear coat. The paint cannot adhere to smooth plastic surfaces. To prevent it from flaking off, the object should always be pre-treated with edding plastic primer.