The paint finish has cracked and wrinkled up like paint stripper has been put on it.
This is caused by the original coating not being compatible with the newly applied coating. Original synthetic and white spirit based paints are the most common causes of this when over coated with fast drying products like cellulose and some two pack products. An isolator product should be used when over coating unknown paint finishes.
The paint finish has small craters in it.
These are commonly referred to as fisheyes and are caused by silicone. The most frequent causes are silicone sealants, sprays such as WD40, polishes and paraffin heaters. Always use a degreasing agent or panel wipe and apply a light first coat to minimise the risk of fisheyes.
The use of an anti-silicone additive should also be considered where possible. For a small additional expense it can save a lot of heartache and many professionals use it as a matter of course. To rectify the
problem, flat the fisheyes smooth, degrease and re-apply the finish.
The paint finish is lumpy and uneven.
This is known as an orange peel effect. It is caused by under thinning of the paint or spraying at too low a pressure. If sufficient paint has been applied, the desired smooth finish can be achieved using wet flatting paper.
I have a cloudy white finish on the item I have sprayed.
This is called blooming. It is normally caused by damp or cold conditions and most often a problem with cellulose paints. Another cause is low grade thinner. The propellant gases used in aerosols can also exacerbate the problem. If sufficient paint has been applied, the blooming will flat and polish out.
The paint finish has tiny bubbles just under the surface.
This is called micro-blistering and can sometimes take several months to appear. Common causes are low grade thinner, solvent entrapment, and water or oil contamination. Solvent entrapment occurs when too much paint has been applied
without leaving the correct drying time between coats. Always drain compressors and inline moisture traps at least once a day if they have a lot of use.