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

June 12th, 2007 - Issue 07

In this issue:

• We continue along on the subject of Surface Preparation and this week we'll discuss Applying Primer Material.

So what is Primer?

Primer is a material that is applied over bare metal once it has been properly prepared. It is classed as one of the undercoats which also includes epoxy primers and sealers.

Epoxy Primer

Epoxy primer is waterproof and is used to protect bare metal from the process of oxidation.

You should need to apply only one or two coats. Painters use these kinds of primer on bare metal before they would apply anything else; being waterproof they:

1. Protect the bare metal.
2. Adhere very well to the metal and provide a perfect base product for undercoats and paint.

Sealers

Sealers are used to protect the undercoats from the materials and the solvent found in the various top coat products and gives them a high adhesive ability. A sealer also helps ensure a uniform color match is achieved.

If you will be applying new paint over an existing paint surface, it is vital that you use a sealer. This is even more important if you aren't sure what brand of paint is currently on the vehicle's finish.

Most sealers don't require any sanding once they have been applied and cured. They form a barrier between the undercoat and the top coat.

Sealers are a great product for any project where new paint will be sprayed over factory finishes that have been baked on at a temperature of approximately 450 degrees Fahrenheit.

Those types of stock paint jobs are very hard and durable, therefore the new paint will have a difficult time penetrating the surface and sticking to it properly.

Using a sealer will make the difference between an adequate and an excellent quality paint job.

Make sure you discuss the right type of sealer product to use with your paint system with a paint and supply store worker.

You will also need to follow the information on the application guide and information sheet regarding proper mixing and other important information provided by the manufacturer.

Once sheet metal has been coated with epoxy primer, primer will cover the minor flaws and scratches caused by sanding.

Make sure, that you use a primer that is made by the same manufacturer as the rest of the paint products in your paint system.

Primer contains solids giving it the ability to cover up imperfections and allows the surface to be sanded until it is perfectly smooth.

Remember that primer is only to be sprayed on a surface in an effort to fill in very small sand scratches and tiny blemishes.

It is the final step for smoothing the body surface to perfection. The undercoats you put on after the primer are used only to seal the base materials from absorbing paint solvents and to increase the overall adhesive ability of the paint.

Make sure you buy enough sandpaper of the correct grade to smooth the primer after application. This is simple to remember, for the first, second and third coat, sand down using 800-grit wet and dry sandpaper.

Be sure to read information sheets and application guides for any primer product you intend to use and remember that selection assistance can always be provided by auto body paint and supply store employees.

Applying Primer and Sealer

Epoxy primers and sealers do not have to be sanded unless you develop runs or imperfections when you're applying them.

If this happens, use fine grade sandpaper to correct your mistakes and then touch-up with a new coat of material.

As previously explained; epoxy primers are sprayed onto bare metal in order to provide a waterproof protection to them.

Most auto restorers will apply epoxy primer products to bare metal prior to removing the old paint and rust.

Some prefer to apply body filler directly to bare metal and then seal the repair after they've applied and sanded primer.

For body panels or vehicles that are going to receive an entirely new paint job, their surfaces are essentially ready for paint.

This is also the case with bodywork that has been scuffed. Therefore, primer and sealer materials should be treated as normal top coat applications and should be sprayed in a spray paint booth after masking.

For bodywork that has been scuffed, you will just need to mask the area and apply sealer. After the sealer has cured you can apply the paint. Make sure you follow all directions from the sealer manufacturer.

If only a portion of the vehicle is going to be shot with primer or sealer, use large strips of masking paper to protect those unaffected areas from overspray, as shown in 'How to Paint a Car - The System' - Part 1.

Whilst using the minimum recommended pressure, fan the spray gently when covering up all the bare spots.

You will want to feather into adjacent areas by releasing the paint gun trigger slowly towards the end of each pass.

You can see this being done in 'How to Paint a Car - The System' - Part 1; notice how the professional painter flicks his wrist at the end of each pass to help perfect uniformly applying the paint.


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 finish off our series on Surface Preparation and cover Finish Sanding & Wax and Grease Remover.

Happy Painting!

Chris Curwen & Dave Gage
www.LearnAutoPainting.com