Repairing Minor Body Damage - Body Filler (Putty) Repairs
1. Body Filler (Putty) Repairs

Selection of Putty:
For body filler repairs, it is extremely important to select the most appropriate type of filler or putty for the work.
The filer type determines the resulting appearance or the repair time required. To select the most appropriate product, it is vitally important to know the technical characteristics of panel putty, intermediate putty, polyester putty, lacquer putty, etc.
For a depression deeper than 3 mm (0.12 in), begin with panel or intermediate filler, form the surface with polyester putty, then apply paint primer surfacer. Use spot or lacquer putty to remove fine scratches. Save time by using polyester putty as much as possible.

Repairs where filler is applied directly over old paint layers may be easier, but care must be taken. Some paint layers types don’t accept filler well and will crack or peel when filler is applied. Always check the old paint layer type and condition. Do not apply filler directly over degraded or lacquer paint layers.
Filler Application Steps:
1.
Remove paint layers on steel panel and clean:
Remove the paint layer to bare metal from a slightly wider area than the immediate filler application area using a disc sander. Make sure to completely remove old paint layer and any rust. Smooth the surface to make a gradual blend it with the surrounding painted areas.
Sand using a double action sander with P80 to P120 sandpaper to smooth out the surface between the bare steel panel and old paint layers. Make a featheredge of 20-30 mm (0.79-1.18 in) while removing fine scratches.
2.
Clean and degrease the filler application area:
Use compressed air to remove dust, dirt, and water. Remove oils with a degreaser.
In rainy or humid weather, warm the surface with an infrared heater to eliminate moisture.
On very cold days, preheating the panel makes body filler easier to spread and reduces drying time.
3.
Mix the filler and hardener.
Using a plastic or wooden body filler scoop, remove the necessary amount of filler from the can. Add the filler and specified ratio of hardener to the mixing board.

Check the appropriate mixing ratio in the product specifications issued by the filler manufacturer.
To prevent air bubbles, knead the filler until the color becomes even while twirling the scoop or spreader.
NOTE: Do not attempt to mix a large amount of filler at one time because it may harden during application. When a large amount is needed, mix and apply the filer in small quantities.

Body filler scoop and spreader maintenance.
Straighten the end of body filler scoops or spreaders using sandpaper and allow a slight bow.
Completely remove hardened filler and keep the tools clean at all times.
4.
Using a body filler spreader
When the filler application area is rectangular, move the spreader in a long direction.






5.
Basic filler application
-1.
The initial layer of filer should be applied to remove sanding scratches. Hold the spreader almost vertically and apply a thin layer of filler while pressing down slightly.

-2.
Apply slightly more filler than necessary in light coats to prevent cavities in the filler caused by air bubbles.

-3.
The final layer of filler should be applied to smooth out the surface by laying the spreader down closer to the surface.

Sanding becomes much easier if filler is used to restore the original shape as much as possible.

2. Body Corners Repairs
Applying Filler at Body Corners:

Using a flexible rubber spreader, apply body filler along the corner area. Apply enough filler to account for sanding required to restore the body contours.


3. Stamping Line Repairs
Applying Filler at Stamping Line:
1.
Apply masking tape along the stamping line and apply body filler to the lower side.
2.
After the filler is halfway set (dried), remove the tape.
3.
Apply tape along the filler line previously applied.
4.
Apply filler on the upper side of the tape.

4. Combined Surface Repairs
Applying Filler on Combined Surface:

On a combined surface area such as a fender wheel arch, where there are both flat and curved surfaces, correct the body contours with filler as much as possible. Otherwise, sanding and polishing time will be increased.
1.
Apply filler on the upper side of rounded panel area.
To make the surface flat, spread the filler from the edge sideways.
2.
Apply filler on the lower side of the rounded area.
To make the surface flat, spread the filler from the edge sideways.
3.
Apply the necessary amount of body filler on the side surface of the rounded area. Use a spreader to move the filler sideways. Repeat for the other side of the rounded area.
4.
Apply filler on sides:
Apply necessary amount of filler on the side plane.
Smooth the surface by moving the spreader sideways while avoiding the curved area.
Smooth the entire surface with repeated motions of the spreader.

5. Body Filler Dry
Drying Body Filler:
Body filler hardens enough to be sanded in 20 to 30 minutes at 68 °F (20 °C) after application. Low temperatures or high humidity will increase the hardening time required. Forced drying may be used to reduce repair time.

NOTE: Rapid or excessive temperature changes will cause body filler to blister, crack or detach from the repair area.

The hardening speed depends on the filler’s thickness. A thick filler application will dry faster than a thinner one.
Follow the body filler or putty manufacturer’s instructions for drying time.

6. Body Filler Sanding
Sanding Body Filler:
1.
Rough sanding
?1.
Rough sand on the entire filler surface until it is smooth.
?2.
When the filler is completely hardened, sand its surface until almost flush with the body surface.
Do not over sand! Leave a finishing margin for hand sanding.
2.
Finishing
Hand sand the filler surface to match the surrounding panel surface using a hand file.