Paint coating your classic car prevents rust and makes it shine, but it can also crack. Understanding the structure of paint and how it can fail is not only helpful, but it will also help you to understand what can cause cracking.
Paint is a liquid mixture commonly composed of pigments (color), binders (polymers) and solvents (water). What is not seen, however, is the polymers that actually hold paint together. Classic car paint has what are called cross-links between its binders that help hold the liquid in place before drying.
After your classic car is painted, cross-links are broken down with chemical catalysts that depend on the type of paint used. Combining an oxidizer with an organic compound creates breaks in polymer chains so that after drying they create spaces for air to get trapped inside when exposed to moisture or water intrusion as well as oxygen resulting in blistering or cracking of classic car paint. As this reaction happens over time, a couple factors come into play: UV light speeds up this process while elevated temperatures do just the opposite by slowing down oxidation reactions.
Classic car paint is rarely the original paint that came on the vehicle. The factory paint may have been damaged or chipped before the vehicle ever reached its owner. This damage will need the classic car body to be cleaned as well as sanded and repainted.
Modern paint systems and the solvents used to apply them are engineered to maintain a film of hard, clear lacquer on top of the basecoat. Over time this lacquer can become cloudy, oxidize or wax over from sitting in storage, but it won't crack like it does on your old Chevy.
Classic car paint was formulated differently for a different time, using different chemicals that didn't resist water and UV radiation as well as modern paints do. The paint was generally applied much thinner than is typical today (a 1/4\" wet film thickness is common), and then rubbed out by hand before allowing it to dry further.
Modern paints use cross-linking chemicals to keep them from drying out and cracking; classic car paints don't have this technology. Quality oil-based enamels like PPG's Deltron will slowly dry over time if they aren't catalyzed with an appropriate catalyst or mixed with enough tackifier (basically very thick paint). Modern enamels are also formulated to be very resistant to water and oxidizing agents, which makes them attractive for vehicle paints, but they aren't as well-suited for classic car use.
High quality modern paint is formulated with additives that attempt to inhibit oxidation before it occurs. This strategy is useless in a car that sits in a garage all summer. Wind, rain, dirt and UV light can cause rapid oxidation of paint before the cross-linking chemicals have a chance to do their job. The result is a vehicle finish that can look \"new\" one minute, and chalky and dull another.
Finding the source of your classic car paint's cracking problem won't be easy; you may need to take it apart down to the bare metal or measure its thickness if you're not familiar with the company's color identification system (many classic cars have more than one paint code).
Acids in rain can wreak havoc on paint. Rather than forming a film, a coat of basecoat sits on top of the clear lacquer, which is vulnerable to air and water. Over time the clear lacquer cracks and peels off, leaving bare metal underneath. A quality wax job will keep this from happening once, but it happens all too easily otherwise.
Most clear coat paint jobs were done in the early 1970's and have been offered up to a car's black interior ever since. Before that time, paints were made with a thicker base and therefore had more gloss. As a result, the clear looked like it was factory-applied. The problem is that these paints don't last nearly as long as they once did. Most of today's clear coats are not in their original can, in fact they haven't been used in years (if ever). They lack the durability of their predecessors, which results in windows turning out dull after extended periods of time. In addition to this, clear coats are highly susceptible to chips- whatever happens to the paint on the car will happen to its clear coat as well- especially when working with wet sanding equipment.
If you own a classic car that is starting to have paint bubbling problems, you probably want to know why. Whether it's a small corner of the car or large sections that are affected by the bubbling, this can mean big problems for your classic. The paint on your vehicle is supposed to last for years and years, but when it starts to crack and bubble up, this can mean the end of your classic car.
So what causes his problem in vehicles There are several factors that can lead to this issue. Rather than being one big problem with your vehicle, there are multiple things that can cause paint cracking and bubbling. These issues include:
When you scratch or damage your classic car's paint, the top layer of your automobile's clear-coat finish is damaged. The topcoat serves as the barrier between your car's basecoat and its original factory color. But, what does the most damage to a classic car paints topcoat
The Sun - Most classic cars are left outside. They're exposed to rain, snow and direct sunlight. All of these elements can damage classic car paint on a daily basis. Without protection against the sun, automobiles receive UV rays that begin to fade the color and weaken the integrity of its surface quickly. A clear-coat finish is supposed to protect your car from these harmful effects, but it will only last as long as it can repair itself. Sooner or later, daily exposure will cause its topcoat layer to crack and peel away. If left alone for any length of time, this problem will persist into permanent damage requiring costly body work repairs or painting entirely by a professional auto body shop in order for you to restore your vehicle back to its original condition..
There are two main categories of natural contaminant that can cause paint to crack in the long term: (1) Atoms and molecules bigger than 1.5 nanometers in size (called ultra fine) and anything larger than that (2) Water or moisture molecules.anything smaller than 0.3 nanometers in size.
Ultra-fine contaminants such as dust and oils are too small to get trapped right at the surface of the paint. They often tend to build up around the edges or any imperfections on the paint surface creating a \"flaky\" effect on a clear coat finish like below.
Rainwater can get trapped between your classic car's panels and cause rusting which leads to unsightly rust stains on your car's finish. This can also weaken paint as water has a tendency to weaken paints over time due to its corrosive nature.
In addition to causing dirt and debris to build up on the paint, mud can accelerate the oxidation process. Oxidation is what causes paint to turn from a shiny paint finish that reflects light, into a dull paint finish that absorbs light. Mud can also reduce the glossiness or shine of the classic car's paint finish.
As the years go on, ultraviolet rays from the sun degrade the paint on your car. This can be especially problematic if your car is parked outside. The sun has a profound effect on vehicular finishes as it's composed of UV light and visible light at the same time. While UVA and UVB cause the most damage, UVC rays are completely absorbed by Earth's atmosphere making them much less harmful to paint jobs.
Most popular classic car paints are lacquers. Lacquers require a clear coat of paint over the top for added durability and protection. First it's important to note that the clear coat does not cure like a regular paint does. In fact, it protects much like an invisible \"fence\" surrounding the paint that keeps moisture out, preventing future damage from occurring. This is why it is imperative to use a quality products which includes flexible solvents and cross linked polymers which cure by electrostatic friction rather than heat.
No - there is no easy, quick and cheap way to remove paint damage from your classic car without proper restorative services. To get the most bang for your buck, it's always best to have the damage professionally restored by an experienced body shop.
Clear coat can be repaired so long as the surface itself is not cracked or peeling. Many auto body shops will offer minor clear coat repairs, but if you're serious about returning your classic car to show quality condition, you'll need to find a speciality shop that offers this service or learn how to do it yourself.
The first step is learning how to identify clear coat problems in the first place. If your car's clear coat has faded, it usually indicates that UV light has destroyed the chemical resins with which it's been formulated. There are several ways to fix this problem, but if UV damage isn't repaired soon enough, rust and oxidation may set in behind the paint job.
If your clear coat is peeling or flaking off of the underlying paint job, your problem may be more serious - though not necessarily beyond repair. While most paints are very hard and durable once cured (within 5 minutes after application), some solvents cannot hold up well against UV light after application (they dry out within a day).
The best way to prevent cracking is to avoid it. Paint should be thoroughly cleaned before applying a fresh coat, and excessive moisture and humidity should be removed. Although dry clean towels are most often recommended, they are not always the best choice. Towels made with cotton or microfiber may leave lint and additional residue on the surface of your classic car paint which can take its toll over time resulting in cracking.
Claying is a great way to remove contaminates from the surface of your paint job. The issue with claying is that you don't know how you are going to damage the paint as you are removing contaminants. Claying will, by default, cause small scratches in the clear coat layer if not done p