Etching Auto Paint: The Right Way To Prep For A Repaint

Self-etching primers are used to prepare metal surfaces for painting. They clean, etch, and prime the surface in one go, creating a strong bond for the paint to adhere to. While it is possible to paint directly over a self-etching primer, it is generally not recommended due to compatibility issues with certain topcoats. To ensure a long-lasting and flawless finish, it is advisable to follow the silent rule of applying another primer over the etch primer, which acts as a protective barrier. This extra layer of protection ensures compatibility and a durable paint job. Additionally, proper surface cleaning and preparation are crucial steps before applying the primer.

Clean the surface with a degreaser and a clean cloth to remove dirt, oil and grime

When preparing a surface for painting, cleaning is the first step. This is especially important if the surface has crumbs, dirt, or grime combined with grease. To clean the surface, use a degreaser and a clean cloth to wipe away all the dirt, oil, and grime. You can use an all-purpose degreaser, such as Krud Kutter Degreaser, or make your own natural cleaner with pantry ingredients. For example, mix one cup of vinegar with four cups of water in a bowl, then pour the mixture into a spray bottle. Spray the solution on the surface and let it sit for about 10 minutes before wiping it off with a gentle cloth. If the area is very greasy, you may need to let the solution sit for a bit longer.

For tough, caked-on grease, you can use a stronger mixture: combine one cup of vinegar, three cups of water, one cup of baking soda, and half a cup of dish soap in a bowl. You can also use a mixture of dish soap, kosher salt, and baking soda to remove dried grease. Soak a sponge with this solution and scrub away the grease. If you're dealing with grease stains on soft surfaces, like clothing, pretreat them with dish soap. Squirt a small amount directly onto the stain, let it soak for about 30 minutes, and then wash the linens in cold water.

After cleaning, the next step is sanding. Sanding creates a rough surface for the primer to adhere to. Use fine-grit sandpaper and sand the surface evenly. Self-etching primer is perfect for metals, especially aluminum and steel, as it cleans, etches, and primes the surface in one go. It prepares metal surfaces for painting by chemically cleaning and micro-etching the surface, creating a strong bond for the paint. However, not all paints work well over self-etching primers, so it's important to choose the right type of paint, such as epoxy paints, urethane paints, or acrylic lacquers.

Once the self-etching primer is applied, you can paint directly over it. However, it's important to allow the primer to cure first to ensure the best results. Check the manufacturer's instructions for specific wait times. After painting, proper care is essential to keep the paint looking fresh. Avoid using harsh chemicals on the new paint for at least a month, and wash the surface regularly with mild soap and water. Apply wax after 30 days to protect the paint from UV rays.

Sand the surface evenly with fine-grit sandpaper

Sanding is an essential step in preparing a surface for painting. It creates a rough texture that the primer can adhere to, ensuring a smooth and durable coat. To achieve an even finish, it is crucial to select the appropriate sandpaper grit size.

When sanding auto paint, opt for fine-grit sandpaper. Fine-grit sandpaper, such as those in the 150-grit range and above, will help you achieve a smoother surface. It is important to avoid coarse-grit sandpaper, as it can leave scratch marks on the surface. Lower grit numbers indicate a coarser grit, while higher numbers denote finer grits.

For a car with multiple layers of paint or light corrosion, 80-grit sandpaper can effectively work through the layers to reach the metal surface. This grit size is also suitable for sanding off light rust. However, for a newer car with a single coat of paint, a finer grit is recommended to avoid aggressive sanding.

When sanding, always use a sanding block to ensure even pressure. Wrap the fine-grit sandpaper around the block and follow an "X" pattern across the surface. This technique will help you distribute pressure evenly and make it easier to sand curved areas. Remember to keep the surface clean and free of dirt, oil, and grime throughout the sanding process.

After sanding, you can proceed with the next steps in the painting process, such as applying a self-etching primer or the paint itself, depending on the specific requirements of your project.

Apply a self-etching primer, which prepares metal surfaces for painting

Self-etching primers are ideal for preparing metal surfaces for painting. They are particularly effective on aluminium and steel. This type of primer combines etching and priming in one step, creating a strong bond for the paint to adhere to.

To apply a self-etching primer, the metal surface must first be cleaned and prepared. Use a degreaser and a clean cloth to wipe away any dirt, oil, or grime. Once the surface is clean, it is important to let it dry thoroughly.

After the surface is dry, you can apply the self-etching primer. This primer can be sprayed on, and it is important to follow the manufacturer's instructions for the best results. The primer should be applied thinly and evenly. For previously painted areas, it is recommended to scuff the surface with 280-320 grit sandpaper before applying the primer.

It is important to note that self-etching primers contain acid, and different manufacturers use different types and amounts of acid. This can lead to compatibility issues with topcoats, so it is crucial to choose the right type of paint. Suitable paint options include epoxy paints, urethane paints, and acrylic lacquers. Enamel paints can also be used but should be tested for compatibility first.

Once the self-etching primer has been applied, it is important to allow it to cure completely before painting. Check the primer's label for specific wait times, as this can vary depending on the product. After the primer has cured, it is ready for paint. You may need to lightly sand the primer before painting, depending on the product.

Choose the right paint—epoxy, urethane, acrylic lacquer or enamel—compatible with the etching primer

When it comes to choosing the right paint for your car, there are several factors to consider. Firstly, understand the paint chemistry and the different options available. The paint you choose should be compatible with the etching primer and suitable for your specific car model and surface material.

The most common types of paint used in automotive applications are urethane and enamel resins. These modern resins achieve a durable finish and are suitable for most car painting projects. Urethane paint, in particular, is known for its excellent adhesion and sealing properties, making it a popular choice for car repairs and respraying.

Epoxy primers are another option, especially if you are working on a quick turnaround project. Epoxy primers provide good adhesion and seal the bare metal from environmental elements. They require manual preparation of the surface by sanding it with 80 to 180-grit sandpaper to create the necessary bite for the epoxy to adhere to.

If you are looking for a smooth and glossy finish, lacquer can be an option. However, it is important to note that lacquer is mixed with highly toxic solvents, which has led to restrictions or illegality in some states or areas. Lacquer is also known for its lack of durability compared to other options.

When choosing your paint, consider the colour scheme you desire. Traditional pigments, such as solid colours, are the most common and offer durability, especially with darker shades. Pearlescent pigments, on the other hand, provide more colour depth but require a two- or three-stage coating process. Lighter shades, in particular, can be more challenging to apply evenly and require a three-stage process.

Specialty colour schemes like metallic flakes, candy colours, and chameleon colours are also available but are the most difficult to apply and may have reduced durability. Candy coats, for example, require a three-step process, including a sparkling base coat, a transparent candy coat, and a high-gloss clear coat. Chameleon paints, or colour-changing paints, exhibit different colours based on the viewing angle and are fairly durable, but they are also challenging to apply.

In summary, consider the compatibility, durability, and finish you desire when choosing the right paint for your car. Urethane and enamel resins are the most common and provide a durable finish, while epoxy primers offer excellent adhesion and sealing properties. Lacquer can provide a glossy finish but may be restricted due to toxic solvents. Finally, carefully select your colour scheme, considering the application process and durability of specialty colours like pearlescent, candy, and chameleon paints.

Apply wax after 30 days to protect the paint from UV rays

After you've painted over an etched surface, it's important to take care of it to keep the paint looking fresh. One of the key steps is to apply wax after 30 days to protect the paint from UV rays.

Waxing your car is like applying sunscreen to protect your skin from the sun. It acts as an intervening layer between the paint and the outside world, including direct sunlight, rain, and dirt. The wax protects the paint from UV rays and prevents the paint from collecting dirt and debris.

There are different formulas of wax available, including pastes, liquids, sprays, and wipe-on/wipe-off waxes. Each type of wax has a slightly different application process, so be sure to follow the manufacturer's instructions carefully. A good-quality wax will not only protect your car's paint but will also give it a beautiful shine and a deep luster.

Waxing your car every three months or so will help increase the longevity of your paint. However, it's important not to overdo it, as this can cause a buildup on the paint's surface. In addition to waxing, you can further protect your car's paint by parking it in a garage or using a high-quality car cover when it's parked outside.

While waxing is an effective way to protect your car's paint from UV rays, it's not the only method. Regular washing can also help prevent damage from UV rays and other environmental factors. Washing your car bi-weekly will help remove contaminants such as bird droppings, which can cause damage within a few hours if combined with UV rays. When washing your car, always use special auto shampoos and soft microfiber towels or mitts to prevent scratches.

Frequently asked questions