Step-by-step instructions: how to properly paint car sills with your own hands

Rusty or peeling sills on Volkswagen Golf, Toyota Corolla or Lada Vesta - not just an aesthetic problem, but a direct threat to the body. If the metal has already begun to “bloom” under the paint, and the anti-gravel coating has chipped off after the winter, you have 1-2 seasons left to wait for corrosion. Painting thresholds with your own hands will cost 3-5 times less than a service station, but only if the technology is followed: incorrect putty, skimping on primer, or ignoring degreasing will lead to paint peeling off in a month.

This article contains a proven scheme of work from metal preparation to finishing varnish, including the choice of materials for different types of damage. Let's look at how to paint plastic sill trims (for example, on Kia Rio or Hyundai Solaris), what is the difference between repairing welds and spot painting of chips, and why epoxy primer Mandatory for areas with risk of corrosion. We also provide a table of compatibility of paints and varnishes for popular car brands.

1. Diagnostics of the condition of thresholds: when to paint and when to cook

Before you reach for the spray paint, inspect the sills for through corrosion. If the metal is rusted through and through (you can see holes or “loose” areas), painting without welding or patches is pointless - in 3-6 months the rust will appear again. Take the test:

• 🔍 Visual inspection: Pry off any peeling paint with a putty knife. If red powder crumbles underneath, this is active corrosion.
• 🩹 Tactile check: Run your finger along the inside of the threshold (door side). Lumps or roughness are a sign of rust under the paintwork.
• 🔧 Tapping: Lightly tap the threshold with a hammer. A dull sound is a signal of metal delamination.

For an accurate diagnosis, use thickness gauge (a device for checking paintwork). The norm for the threshold is 0.8–1.2 mm. Readings below 0.6 mm mean that the metal is corroded and requires replacement of the area.

⚠️ Attention: If there are paint blisters (“bugs”) on the threshold, do not scrape them off with a knife! In 90% of cases, pockets of corrosion are hidden underneath them. Correct algorithm: strip to metal, process rust converter (for example, Tsinkar), and then putty.

2. Materials and tools: what to buy for a quality result

Saving on materials is the main reason why paint on thresholds peels off after a year. Below is the list mandatory components indicating brands tested by masters:

Material/Tool	Purpose	Recommended Brands	Approximate price (2026)
Epoxy primer	Anti-corrosion protection of metal	Novol Protect 360, Body 960	800–1,200 ₽/l
Acrylic primer	Leveling the surface before painting	Mobihel, Sikkens	600–900 ₽/l
Auto enamel (base)	Color coating	Duxone, Standox (selection by code)	1,500–3,000 ₽/l
Varnish (2K)	Protection and shine	Vika, Spies Hecker	1,200–2,000 ₽/l
Rust converter	Stop corrosion	Tsinkar, Runway	200–400 ₽/bottle

Tools you will need:

• 🔨 Grinder (or drill with a brush attachment) for cleaning.
• 🧴 Sandpaper set: P80 (rough) P240 (average), P600-P1000 (finish).
• 🎨 Spray gun with a 1.3–1.4 mm nozzle (for base and varnish). For spray cans - be sure to buy an adapter for uniform spraying.
• 🧲 Masking tape and film for pasting adjacent parts.

3. Preparation of thresholds: cleaning, putty, degreasing

80% of success depends on the quality of preparation. Even expensive paint will peel if the metal is not free of rust or grease. Follow the algorithm:

1. Removing old coating. Use a sander with an attachment P80 to remove paint and rust to bare metal. In hard-to-reach places (for example, under door seals), work by hand with sandpaper P120.
2. Rust Treatment. Apply rust converter brush, leave for 15–20 minutes, then rinse with water and dry. For deep corrosion, repeat the procedure 2 times.
3. Putty. If there are dents or uneven spots on the threshold, use polyester putty (for example, Novol Polyester). Apply in thin layers (maximum 3mm at a time), drying for 15-20 minutes between coats.
4. Sanding putty. After drying, sand the surface with sandpaper. P240, then P400 for smoothness. Check with your hand - there should be no lumps.
5. Degreasing. Wipe the threshold antisilicon (for example, App W900) and a lint-free cloth. Do not use gasoline or thinner - they leave a film!

⚠️ Attention: If the thresholds on your car (for example, Renault Duster or Nissan Qashqai) have plastic covers, remove them before painting! Paint that gets on plastic does not adhere well and peels off quickly. The linings are painted separately with special paint for plastic (for example, Plasti Dip).

The thresholds are cleaned to metal without traces of rust|

The putty (if used) is completely dry and sanded|

The surface is degreased with anti-silicone|

Adjacent parts (doors, bumper) are covered with masking tape |

The temperature in the garage is not lower than +15°C (for proper polymerization)-->

4. Priming: why epoxy primer will save you from rust

Many people skip this step or use cheap acrylic primer - this is a mistake. Epoxy primer creates a sealed layer that:

• 🛡️ Blocks access of moisture to metal (prevents corrosion).
• 🔗 Improves paint adhesion to the surface.
• ⚡ Withstands temperature changes (relevant for winter use).

Application technology:

1. Dilute the primer with the hardener in the proportion indicated on the can (usually 2:1 or 4:1).
2. Apply the 1st coat thinly, holding the gun at a distance of 20–25 cm. Let dry for 10–15 minutes.
3. Apply the 2nd layer more densely. Dry for 1–2 hours (at +20°C).
4. Sand the soil with sandpaper P600–P800 for smoothness. Remove dust with compressed air.

For areas at risk of corrosion (eg lower edge of threshold) add a 3rd layer of primer. After sanding, degrease the surface again.

What is the difference between epoxy primer and acrylic primer?

Epoxy primer creates a chemically resistant coating that is resistant to salts and moisture, but takes longer to dry (up to 12 hours). Acrylic primer polymerizes faster (1-2 hours), but does not protect against corrosion - it is used only for leveling the surface before painting. For thresholds be sure to combine both types: first epoxy (1-2 layers), then acrylic (1 layer).

5. Painting thresholds: technique of applying paint and varnish

For uniform coverage, follow these rules:

• 🌡️ Temperature: Paint at +18–25°C. At low temperatures the paint looks like an “orange peel”, at high temperatures it bubbles.
• 🎯 Distance: Hold the spray gun or can at a distance of 20-25 cm from the surface. Closer - drips, further - “dust”.
• 🔄 Speed: Move your hand at a speed of 30–40 cm/sec. You can't stay in one place!
• 🔲 overlap: Each new pass must overlap the previous one by 50%. This avoids stripes.

Work order:

1. Base coat (paint). Apply 2-3 thin coats with 10-15 minutes drying in between. Required for metallic or pearlescent paints. interlayer drying (20 minutes).
2. Varnish. 30 minutes after the last coat of paint, apply varnish in 2 layers. The first is thin (“fog”), the second is dense. Let dry for 24 hours before polishing.

For cans: Shake for 2-3 minutes before use. Try spraying on cardboard - the stream should be uniform, without splashing.

6. Drying and polishing: how to avoid matting of the varnish

Improper drying is the #1 cause of cloudy polish. Follow the rules:

• ⏳ Time: At +20°C the varnish cures within 24 hours. You cannot speed up the process with a hairdryer - microbubbles will form.
• 🚫 Prohibitions: Do not wash your car for 7 days after painting. Avoid parking under trees (the resin will ruin the varnish).
• 🛠️ Polishing: After 3-4 days, polish the thresholds abrasive paste (for example, 3M 09374) to remove minor defects. Use the polisher at low speed (1,000–1,500 rpm).

If the varnish remains cloudy after drying, the reasons may be:

Defect	Reason	How to fix
Matt varnish	High humidity during drying or dirt in the varnish	Polish with abrasive paste P2000
Bubbles	Too thick layer or drying at high temperature	Sanding P1200 + reapplying varnish
Drips	Close distance when spraying or excess varnish	Cut off streaks with a knife, sand, apply a new coat

7. Common mistakes and how to avoid them

Even experienced craftsmen make mistakes. Here are the top 5 mistakes when painting thresholds:

• 🔥 Painting for rust. If corrosion is not removed, it will “grow” through the paint in 2–3 months. Solution: strip to metal + rust converter.
• 🌧️ Working in a dusty or damp environment. Dust and condensation settle on fresh paint. Solution: Paint in a clean garage with an exhaust hood or outside in calm weather.
• 🎨 Saving on soil. Without epoxy primer, the thresholds will rust within a year. Solution: Apply 2 layers of epoxy + 1 layer of acrylic primer.
• 🔍 Ignoring defatting. Grease stains from fingers or silicone from polish lead to paint peeling. Solution: degrease antisilicon before each layer.
• 🚗 Painting without removing overlays. The paint on plastic trims cracks after 2-3 months. Solution: Remove the covers or paint them separately with plastic paint.

FAQ: Answers to frequently asked questions

Is it possible to paint thresholds in winter in an unheated garage?

Technically possible, but the risk of paint defects increases by 3 times. At temperatures below +10°C:

• Varnish and paint take longer to dry (up to 48 hours).
• The likelihood of matting of the varnish due to condensation increases.
• Epoxy primer may not cure completely.

Solution: Use infrared heater for local warming of thresholds up to +18–20°C. Do not direct hot air directly onto the painted surface!

How to choose paint color for thresholds if the color code is unknown?

There are 3 reliable ways:

1. By VIN code. On most cars (for example, Skoda Octavia or Ford Focus) The paint code is located on a plate under the hood or in the trunk. Enter it in the directory DuPont or Standox.
2. Computer selection. In auto shops with equipment Spectrophotometers They scan the body color and produce the paint in 15 minutes.
3. Visual selection. Take the gas filler flap with you (if it is painted in body color) and compare the shades under daylight.

For metallics and pearls, be sure to check effect index (for example, “medium metallic” or “strong pearlescent”) - it affects the final shade.

How many layers of paint and varnish should I apply to the thresholds?

Optimal design for durability:

• Paint (base): 2–3 layers. For dark colors (black, blue) - 3 layers, for light colors (white, silver) - 2.
• Varnish: 2 layers. The first is thin (“fog”), the second is dense (“wet”).

If the thresholds are heavily damaged, add 1 layer insulating soil between acrylic primer and paint.

How to paint plastic door sill trims?

Plastic requires special materials:

• Paint: Use paint for plastic (for example, Plasti Dip or Krylon Fusion). It is elastic and does not crack.
• Soil: Adhesive primer (for example, Novol Plastic Primer) for better grip.
• Varnish: Not required, but if you apply, take it soft varnish (for example, Vika Soft).

Be sure to degrease the plastic before painting. antistatic (for example, App W400) - it removes static electricity, which attracts dust.

How to protect thresholds after painting from chips and rust?

For results to last longer than 2-3 years:

• 🛡️Apply anti-gravel film (for example, 3M Scotchgard) to the lower part of the threshold.
• 🧴 Treat the thresholds wax or ceramics 2 weeks after painting (for example, Ceramic Pro).
• 🚿 Wash your car using a contactless method (without brushes) for the first 3 months.
• ❄️ In winter, after a trip through salt, rinse the thresholds with water and apply anti-corrosion spray (for example, Liqui Moly Unterbodenschutz).