Some parts are particularly sensitive to excess product, such as vertical parts (flaps, doors, etc.), which may result in possible paint defects, such as sagging clearcoat.
I got into a discussion on another forum with a guy who stated that anything more than 3 coats of clear is excessive and flowcoating, for example three coats sand, then three more makes the paint look heavy and will cause excessive chipping.
Remove the Clear Coat by Wet and Dry Sanding
Take the wet 400 grit sandpaper and begin wet-sanding the clear coat material. This is a crucial step in which a canvas is created for the rest of the process, so those in auto body technician careers must be careful to sand the vehicle's surface evenly.
Remove Peeling or Damaged Clear Coat
Use fine automotive Scotch-Brite to rub the most damaged areas first. Use light to medium pressure and try to knock off all the peeling flakes. If the color coat is exposed, use very light pressure and focus on the borders. You can also use fine sandpaper.
Additional Coats: If you're seeking an exceptionally glossy finish or extra protection, you can apply three or more coats. However, be cautious not to overdo it, as excessive coats can lead to a "orange peel" texture.
Too thick clear coat
Cracking and Peeling: A thick clear coat is more prone to cracking and peeling over time, especially when exposed to extreme temperatures or direct sunlight. This can lead to flaking and the clear coat separating from the base layers.
The window of opportunity to add more coats is 24 hours. The only window of danger is if you go past 24 hours. You must then sand and apply another coat of color before clearing.
Often, the beginning stages of clear coat failure appear as subtly dull or white patches on the horizontal surfaces of a vehicle. As the oxidation process continues, paint eventually starts to crack and flake (see the picture above.) Sometimes paint failure is so severe it looks like skin shed by a snake.
It takes around 24 to 48 hours for a clear coat to dry, but experts recommend not driving your vehicle until after the 48-hour period just to be safe. This is because even though the clear coat has technically dried, it can still be soft enough to get damaged easily.
Buffing clear coats make scratches and nicks disappear. It also makes the paint job look fresh and new again. However, clear coats will always be prone to damage, and buffing is an excellent way to eliminate any imperfections.
Now 7 microns doesnt sound all that much, but I would think you would only want to remove at most, maybe 20-25 microns, or just over half of the available clear coat before you start to run into trouble, such as clear coat failure.
Sanding or stripping chemicals are your two options. I'd stay away from chemicals as they're indiscriminate and hard to control. Sanding with high grits will remove the clear coat but also affect any surrounding or underlying layers.
Incorrect clear coat application technique
Applying the first clear coat layer with excessive pressure or at too short a distance from the part can cause the aluminium particles to be removed from the surface, which can lead to the appearance of clouding or cloudiness.
Well, there's a way to cut down on the hassle and repair a slightly peeling clear coat by respraying a small area and blending it in with the rest of the panel. You can do it yourself and spend only a few hundred dollars on tools and supplies, some of which you may already have.
Avoiding excess clearcoat
Some parts are particularly sensitive to excess product, such as vertical parts (flaps, doors, etc.), which may result in possible paint defects, such as sagging clearcoat.
UV rays are the primary cause of damage to your vehicle's clear coat, resulting in oxidation and peeling. Urethane, a component of most automotive paints, is degraded by UV rays.
A Coating/Paint Thickness Gauge is used to measure exactly how thick the layer of clear coat/paint is on the car. Once you know how thick these layers are, you will know how much of the surface you can abrade away without burning through the clear coat or paint.
Spray with strokes that are too fast or too far apart, and you'll get a similar matte or less than glossy finish. Practice on the test card or another body panel if you have one. Proper clear coat application will result in a glossy final finish.
In short, that rough texture that you feel is basically a mix of micro-level dirt that has stuck to your clear coat that won't come off with a simple wash. It can be things like industrial fallout, paint overspray, metal shavings, dust, etc…
Therefore the existing clear coat will need to be sanded down, otherwise, with a new paint layer, the previous layer can fail, cause the new finish to clear or peel away.
The clear coat rejuvenates the paint giving it a natural sheen, protecting it from harmful environmental factors that cause wear and tear and saves the paint from scratches. The clear coat drying time on cars is about 12 to 48 hours. That said the paint takes around 30 days to get fully cured.
Clear Coat
Just like with the base coat, sanding between coats of the clear coat is not recommended. If there is some imperfection or defects, then sand it down very, very carefully. This is owing to how thin the clear coat is.
Applying the second coat too early will result in streaks, peeling paint, and uneven color. Not only will this ruin the entire project but it'll cost additional money to get more paint in some occasions. It's best to wait for the first coat to dry.