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With Chris Curwen & Expert Auto Painter - Dave Gage (Car Cosmetics)

July 17th, 2007 - Issue 12

In this issue:

• We continue on the topic of Bodywork repair and this week cover Rust Repair.

Rust repair may at times be more necessary than collision repair, depending upon your geographical location and/or where you have kept your vehicle.

If you spot rust, you will need to detect whether it is only found on the surface or if it is corrosion that penetrates through the entire panel.

Surface rust, with solid metal found beneath it, can be easily removed with sanding followed by the application of epoxy primer.

If the rust problem is more advanced and has either gone through or heavily pitted the sheet metal, it will be necessary for you to perform more extensive repairs before applying paint.

This can be done by media blasting or by using a chemical stripper followed by applying epoxy primer. You will then need to follow up with an application of high-build primer.

More severe rust problems will need to be restored with the use of patch panels welded onto existing bodywork.

Rust Removal by Sanding

In order to remove surface rust from solid sheet metal, use a sanding block and 80- to 100-grit sandpaper.

Once all the rust is gone and you're down to either bare metal or painted metal, wipe the panel down using wax and grease remover, next coat the panel with epoxy primer. Sanding scratches left behind from using the coarse grit sandpaper will provide excellent adhesion for the epoxy primer.

Always remember to take care of any dents by repairing or filling them and then applying a coat of high build primer before you block sand.

Rust Removal by Panel Replacement

For panels that are damaged beyond repair because of widespread rust, you are better off replacing them with healthy new ones. If you are replacing a complete panel such as a door, the process is the same for collision repair as it is for rust repair.

It really doesn't matter if you decide to use genuine new factory replacement panels, cheaper after market units or used parts; what is important is that you search for the best products that will fit your price range.

The surface preparation process may be slightly different, compared with the rest of the vehicle, when you use new replacement panels.

Make sure you clean such panels using wax and grease remover before you do anything else.

You will have to scuff the surface using a Scotch Brite pad otherwise the primer and paint won't adhere properly to it.

You should ask an auto body paint and supply store worker for their recommendations on the correct undercoat product necessary to prep the panel that is compatible with your adopted paint system.

It's important to remember that any application of primer undercoats should be completed before you install the panel back onto the vehicle.

In addition, only apply the top coats once the panel has been correctly installed and aligned making it easier for you to accomplish proper paint blending.

Installing Patch Panels

Patch panels are generally used in the restoration of vintage vehicles; however they are becoming more commonly used on later model vehicles as the average vehicle age increases.

A patch panel is the best way to repair a portion of a panel such as the lower part of a door or a portion of the main body including the rear quarter panel that is beyond all other means of repair.

For those of you working on a mainstream vehicle, it is very likely a patch panel for your particular application will be available.

Don't worry if the available patch panel is not large enough to cover the entire area that needs to be repaired, it may still be useful for repairing the elaborate body lines of the damaged area.

To install a patch panel, you will of course have to remove the damaged metal in order to weld the patch panel into that location.

It is important therefore that you compare the new panel to the area being replaced so that you know how much of the old metal to remove.

A range of tools such as a plasma cutter, die grinder, reciprocating saw or tin snips can be used to cut out the damaged section.

Once you've removed the damaged section, set the patch panel in its place, check it for proper alignment, followed by clamping it into its precise location and then finally weld.

The type of weld you want to use will depend on the panel you are replacing, the type of welder you have available and either the operator's or your own skills.

Once you have finished welding, clean the patched area with wax and grease remover, apply epoxy primer and finish the bodywork to the surrounding area.

Follow up with primer and then block sand as needed before you apply sealer and top coats.


That's all we have for you this week. Thank you very much for reading. We both hope this issue has been of valued interest to you.

Next week we'll continue on the topic of Bodywork repair and talk about how you get all body surfaces as straight and as flat as possible.

Happy Painting!

Chris Curwen & Dave Gage
www.LearnAutoPainting.com