Filling dented bodywork

Whether you are repairing large or small dents to vehicle bodywork you will have to know how to fill and sand the damaged areas properly. This is the only way you can achieve a professional looking repair, short of replacing the panel entirely.

The first thing you will need to do is remove all the paint and primer from the damaged area, and 4 or 5cm beyond it. Car body filler will not adhere securely to anything except bare metal. This does not need a subtle approach, so you can either do it all by hand with a coarse sandpaper or use a circular power tool sander attachment to strip it off, and then finish any awkward areas by hand.

Body fillers are an epoxy resin, this basically means that you will have 2 substances to mix together. The base material provides the 'bulk' of the filler and this will stay in a viscous 'putty like' state until mixed with a small amount of the catalyst which activates it. After about 6 or 7 minutes following a thorough mixing the two substances will start to harden into an extremely strong solid material. This means you have to work quickly!

The two substances should be mixed on a clean dry surface, but bear in mind that once it sets it won't come off easily, so something disposable like an empty clean plastic food container should do the trick. Follow the directions on the can.

Apply the filler quickly and liberally using the applicator across all the exposed metal. Actually push it in to the dent so that there are no air pockets. Ensure that when the cavity is filled, it 'bulges' out consistently by a few millimetres above the level of the surrounding panel, this will allow you to sand it 'down' to the level of the surrounding bodywork.

When the filler has hardened (if in doubt, give it another hour or two!) you can start sanding. Its probably best to do this part by hand. If you don't already have one, buy a flexible (rubber ideally) sanding block. The flexibility is important because it allows your sanding to follow the contours of the body panel consistently.

Using a 150 grit sandpaper on your block, start sanding the filled area. Focus your pressure on the filled area using a circular motion, when it begins to level out, ease off and stop before it becomes level with the surrounding panel.

Now change your sandpaper to a finer 220 grit and with very gentle pressure, continue until the filled area follows the contour of the rest of the panel. Be patient at this stage, remember you can sand the filler away, but you can't put it back - at least not without a lot of hassle!

Ok so now you think you have created the perfect repair? Well almost! When paint is applied to a surface, it will show up every tiny imperfection, so there is just one more stage you need to go through for that perfect finish.

To create that perfect finish you will need something called spot putty. This is like a super fine filler that does not require mixing but it will remove all the micro imperfections that the coarser epoxy can't manage.

Spread a thin layer over the entire area of the repair and possibly a centimetre or so beyond. This material will harden more quickly than regular filler because the layer is thinner.

When the putty is dry (check the instructions) and using a super fine (400 grit or finer) sandpaper, sand the area very gently by hand. Check if the surface is smooth with your hand. When the surface feels right, that means it probably is.

You are now ready to paint the repair.

Please remember unless you are extremely confident in all aspects of this process, please take your vehicle into an accident repair centre as rectifying a bad repair or mismatch paint can be more costly that the original repair would have been.

If in doubt please leave this type of work to the experts!

Cost free bodywork and crash repairs

At Accident Repair Finder we can help you get repairs and a comparable replacement car while your car is being repaired. If your accident was not your fault, we can provide these services for you absolutely free because we claim all the costs back directly from the at-fault party's insurance company.

For more information please ring 0845 6768898 or complete our online claim form.