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

July 24th, 2007 - Issue 13

In this issue:

• We continue on the topic of Bodywork repair and talk about how you get all body surfaces as straight as possible.
• Questions & Answers: This week we help Yvon Benoit with his question:

"I would like to know how to mix car paint so I can use it in my spray gun, including how much thinner & hardener should I use?"

The objective to any type of vehicle bodywork repair is to get the wings, bonnet, doors and any other parts as straight as possible.

Panels that are meant to be straight should be left exactly that and panels that are meant to be curved should be left as smooth curves and have no angles of any kind. The use of a long board when sanding will help to minimize any ripples.

Using Body Filler

While you may not notice it in the beginning, after you apply a fresh coat of paint, any dents remaining on the surface will stick out like the proverbial sore thumb.

Even if you can't visibly see any imperfections when you initially examine your vehicle bodywork, if your car has ever been in a parking lot or a double driveway, there is bound to be at least one minor door dent.

You can repair minor door dents up to 1/8 of an inch deep using body filler. Simply scuff the dented area down to bare metal or epoxy primer.

After using whatever tool is necessary to straighten the metal to very near its original contour, you would apply, using a body filler spreader, two or three thin coats of filler mixed with the right amount of hardener to match the final contour.

Glazing putty can then be used to fill any pinholes that remain in the sanded body filler.

Always read the instructions carefully for the type of filler you are using so that you know exactly how and when to begin working with it.

After rough shaping using 80- or 100-grit sandpaper, sand the entire area with finer sandpaper until it blends into the surrounding area.

You can see the use of body filler being professionally demonstrated in 'How to Paint a Car - The System' - Part 1.

Aligning Panels and Fitting Gaps

It can be tricky to get panels to fit with each other when you install them onto a vehicle.

You need to check to see if the gaps between the panels are the same width consistently. Are they all in line or does a panel stick out farther than one next to it?

Some vehicles just have better panel fit when they are made in the factory. However, it is still your job to get them to fit as near to their original positioning as possible so never rush this task.

Doors may have to be moved on their hinges somewhat to align the door latch mechanism or make the body-lines match. Most doors have a slight amount of adjust-ability built in to accommodate for normal wear.

Hood lids for example may present the biggest problem, as any gap problems will need to be evenly split between the two sides.

It will take some adjusting to get consistent gaps across the entire vehicle. You may have to add or remove material from the panels to accomplish the task. It all depends on how perfect you want your project to look when finished.

Professional body shops attempt to get the gaps between the panels to be the same thickness as that of a paint stir stick. Many of the newer vehicles have gaps that are up to three times as thick as a stir stick. Make sure yours is consistent throughout.

Be careful not to get the panels too tight in areas where you have applied body filler. You want to get the surface smooth but without too much build-up.

This is achieved by making sure the area being filled isn't higher than it was intended to be and therefore heightens the surface of the surrounding area.

As previously mentioned, the correct surface height is very important before application of body filler.

Questions & Answers

Today Yvon Asks:

"I would like to know how to mix car paint so I can use it in my spray gun, including how much thinner & hardener should I use?"

You see Yvon, it really depends on what type of paint you are using.

If it is a 2 pack type paint then you would generally use 2 parts paint to 1 part hardener, with a touch of thinner, usually 10%.

So the rule of thumb would be a ratio of 100:50:10 of paint:hardener:thinner respectively.

Auto painting is a systematic process; if you prepare the surface of your vehicle properly, mix all products correctly and apply them properly, then you will be left with an excellent paint job.

The proper mixing ratios are included with product information sheets. Calibrated mixing cups and measuring sticks are available at your auto paint and supply store.

If you are ever in any doubt Yvon, simply ask for advice from a member of staff who you bought your paint from, it is their job to guide you accurately.

Color shade mixing on the other hand is really a job you should leave to the full-time professionals.

They will follow stock vehicle color codes or codes attained from paint chip catalogues. This service they provide forms part of the paint system you purchase.

For further information on Paint Mixing including how to use calibrated mix cups/sticks, please refer to 'How to Paint a Car - The Written Guide'.

We hope this helps you Yvon.


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 making sure all surfaces are flat and cleaning sanded surfaces before undercoat applications.

Happy Painting!

Chris Curwen & Dave Gage
www.LearnAutoPainting.com