"Painting Your Car? Don’t Make These 5 Rookie Mistakes"

Painting a car is a detailed and complex process. There are many small steps that, if skipped or done incorrectly, can affect not only the final look of your paint job but also its long-term durability. In this post, we’ll walk you through five common mistakes most beginners make — and how to avoid them.

1. ❌ Wrong Mixing of Products

When working with automotive paints, you're dealing with chemical reactions. Most products require two or more components — such as base, hardener, and reducer — to be mixed in precise ratios for the reaction to occur properly.

While some "experts" like to eyeball the mixture or use their own formulas, this is a recipe for failure. You should always follow the manufacturer’s instructions, ideally found in the product’s Technical Data Sheet (TDS).

Pro Tip: Most manufacturers publish TDS documents online. Just Google the brand and product number followed by "TDS PDF."
Example: General 4010 TDS PDF

What Can Go Wrong:

• Undercatalyzing: Not enough hardener — the product may never fully cure.

• Overcatalyzing: Too much hardener — the reaction might happen too fast, leading to defects like “crocodile skin,” poor surface finish, or even long-term delamination.

✅ Recommendation:

• Find the correct mixing ratios for all products you’re using.

• Use a calibrated mixing cup from your paint supplier.

• Measure precisely. A small margin of error (around 5%) is usually okay, but always aim to be as accurate as possible.

2. 🧱 Not Priming Surfaces Properly (Plastic or Metal)

Surface preparation is the foundation of any successful paint job. If your base isn’t solid, no topcoat will ever look or last the way it should. How you prep and prime depends on what you're painting.

🔩 Bare Metal:

Use a Direct-To-Metal (DTM) primer if you plan to paint shortly after.
If the car will sit in primer for a long time before final painting, use an epoxy primer instead.

Pro Tip: Even quality DTM primers can absorb moisture over time. For long-term protection during restorations, epoxy is the safer bet.

🛠️ Painted Metal (Paint in Bad Shape):

If the old paint is flaking, lifting, or showing signs of delamination or discoloration — it’s compromised. Fresh primer or paint won’t fix it, and in fact, solvents in the new products can make the problem worse.

✅ In these cases, sand down to bare metal and restart with proper primer (DTM or epoxy).

🔧 Painted Metal (Paint in Good Shape):

If the existing paint is in good condition:

• Scuff it with 320–400 grit sandpaper to promote adhesion.

• Use a regular primer (no need for DTM).

🧽 Plastics:

Plastic components (bumpers, trims, mirrors) require a different approach:

• Scuff using 400 grit flexible sandpaper or a scuff pad.

• Apply a plastic adhesion promoter (like Klean Strip Bulldog).

• From there, you can either go directly to paint or follow up with primer/sealer depending on your system and color needs.

Note: Some adhesion promoters are tinted gray to help with coverage — saving you a step if your topcoat is a light color.

🩹 Body Filler:

Painting over body filler requires special attention. While fillers like Bondo or polyester putty are great for shaping and repairing panels, they’re porous and not meant to be painted directly.

❌ Common Mistakes:

• Skipping primer over filler.

• Using the wrong type of primer.

• Not sanding smooth enough before priming.

✅ Best Practice:

• Once the filler is fully cured, sand it smooth — typically ending with 180 to 220 grit.

• Apply a 2K high-build primer or epoxy primer over the filler. These primers help fill minor sanding scratches and seal the porous surface.

• After priming, block sand the area with 320–400 grit to level it out before applying basecoat.

Pro Tip: Avoid using lacquer primer over filler — it may shrink over time and reveal sanding lines. Stick with modern 2K urethane or epoxy systems for a longer-lasting, smoother result.

3. 🎯 Not Checking Your Color Before Spraying

Color mismatches are one of the most frustrating issues in auto painting. Even if you’re using the correct formula, variations in batches or substrates can cause differences.

Some paint brands may offer better consistency in color matching, but with so many external variables at play, it's never worth taking the risk without verifying the match yourself.

Never assume a color match is accurate until you’ve confirmed it with your own eyes.

✅ Always do a test spray-out:

• Use a spray-out card or a small hidden section of the car.

• Let it dry fully and compare it in natural light.

• Blend panels when possible to reduce visible differences.
  
  

  Pro Tip: Metallics and pearls can be especially tricky — their appearance can shift depending on angle, lighting, and spray technique. Factors like air pressure, drop coats, and gun tip size can all affect the final look. That’s why doing test spray-outs under the same conditions you’ll use for the actual job is absolutely essential.

4. 🌡️ Painting in the Wrong Environment

If you have ever used a flash light in a dark room you probably have seen all the dust and particles that can be in the air at all times. Even if you cannot feel them or see theM in normal light, this particles will stick to your fresh paint job an can cause a number of defects. this is why the environment matters more than most people realize. Factors like temperature, humidity, and air cleanliness can all affect your final result.

❌ Common Mistakes:

• Painting in dusty garages.

• Painting in high humidity (can cause cloudiness or “blushing”).

• Painting in cold weather (slows drying and curing).

• Poor lighting (makes it hard to spot imperfections).

• Places with oil or silicone contamination can lead to "Fish Eyes" on the clear.

✅ Best Practice:

• Paint in a clean, enclosed area with good lighting and ventilation.

• Ideal temperature: 70°F (21°C) with low to moderate humidity.

• Use filters or air dryers if your compressor tends to add moisture to the air.

5. 🧼 Not Cleaning the Surface Properly

You can sand and prime like a pro, but if the surface isn’t clean, your paint job is toast. Grease, wax, silicone, or even leftover overspray can cause nasty issues like fisheyes, craters, and peeling.

✅ Follow this process:

1. Blow Off Dust:
   Once the car is fully prepped and ready for paint, use an air hose to blow off the entire surface. This helps remove sanding dust and particles stuck in the sanding scratches — which is exactly where you want the new paint to bond.

2. Wipe with Wax & Grease Remover:
   Use a wax and grease remover with a clean, lint-free cloth (not shop rags). Wipe down the entire area to be painted.
   Dispose of the cloth once it shows signs of buildup — if the cloth comes away dirty, the surface isn’t clean yet. Your wipe should leave the cloth mostly clean when the surface is ready.

3. Don’t Touch!
   Avoid touching the surface with bare hands after cleaning — skin oils can undo your prep work and cause defects in the paint.

4. Use a Tack Rag Before Painting:
   Right before applying paint, gently wipe the surface with a tack rag. This will pick up any remaining dust or fine overspray from previous coats, giving you the cleanest surface possible for your next layer.

Final Thoughts:

Auto painting is part art, part science — but the most important factor is attention to detail. If you slow down, follow the correct prep steps, and use quality materials properly, your results will speak for themselves.