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

June 19th, 2007 - Issue 08

In this issue:

• We'll conclude our mini-series on Surface Preparation and cover Finish Sanding & Wax and Grease Remover.

Whew! There's quite a bit to get through this week so please bare with us! Let's make a start...

Sanding Existing Paint Surfaces: You must always remember to sand (scuff in this case) old paint surfaces before you apply any new paint.

The purpose of scuffing is to dull any shiny surfaces so that any new layers of paint material will have an absorbent base to adhere to.

This is even more critical if you're dealing with factory paint jobs that were baked on at approx. 450 degrees Fahrenheit.

If you don't follow this step, the common result will be that the new paint will simply flake off.

A super hard, baked on factory finish isn't going to allow anything especially paint to permeate it easily, so ensure that you always scuff the existing surface.

A fine grade Scotch Brite pad will work a treat for scuffing baked-on paint finishes, as demonstrated in 'How to Paint a Car' - Part 1.

They leave behind a rough finish that works well for fresh coats from your paint system to adhere to effectively.

You can just as easily use 500- to 600-grit sandpaper to scuff shiny paint finishes. Ensure that you scuff and sand in all directions to maximize the process.

Getting the Surface Smooth: Prior to the painting process, you will have to work at getting all of the repaired body panels as smooth as is humanly possible.

You can only accomplish this task by block sanding any areas that feel rough. This could be a small area or the entire vehicle.

Take a slow walk around your vehicle and pay very close attention to the surface, use your hands to feel your way around; you finger tips may pick up on something that your eyes don't.

Any imperfections that you discover at this point, while it is in primer or scuffed paint, are going to be magnified once you add new paint.

Fine Sandpaper: After you have finished using 400-grit sandpaper on your vehicle or repair area, some sanding scratches may still remain that will show up clearly when you paint over them.

These will need to be taken care of with finer grade sandpaper such as 600-grit.

If you require an extremely elaborate paint job finish, try block sanding the entire vehicle using 800-grit and then 1000-grit sandpaper. For the greatest results, always steadily work your way up through the grades of sandpaper.

If you went from 400-grit to 1000-grit sandpaper, the process would take you much longer than it should, so allow each grade to do its own individual work.

Completely hand-sanding a car for paint should only take you a day or two at the most. If you were working on your own car at home, this isn't a big deal. Take your time and make sure you accomplish this task thoroughly.

Here are a few tips to help you along the way:

* Always use quality sandpaper made for automotive paint work; 3M is a common brand.

You can pick up ideal sandpaper down at your automotive paint supply store. It may seem expensive to buy at first, but it will pay for itself in the long run by lasting longer and not clogging as easily as normal house-hold sandpaper.

If you plan to do a lot of sanding, buying sandpaper by the pack or box will save you a fortune long-term and the inconvenience of trips back to the store to buy more.

* Use a semi-hard rubber block inside the folded paper as often as possible to even the sanding pressure and give a blocking effect.

In the opening scene of 'How to Paint a Car' - Part 1, you can quite easily see Mike using a rubber block at all times whilst he is sanding.

Use your fingertips to get into corners but never sand with your fingertips in open areas. It leaves uneven ridges.

Also, when using a block, don't sand parallel to an edge or a ridge, otherwise the outer edge of the block/paper cuts a ridge in the surface.

* You would be well advised to fold the sandpaper into thirds so it won't wrinkle or ball up, is easier to hold onto and can be turned regularly for a fresh surface.

Make sure you wear protective rubber gloves with this clever little method. Otherwise, as one side of the paper is sanding the car, the other side will be sanding your hand!

We could talk forever on the topic of surface prep so we'd like to end on Wax & Grease Remover.

Wax & Grease Remover is a clear liquid cleaner that removes wax, grease, oils and any silicone residue that might be on the vehicle surface.

Its application is simple: apply it using a clean white cloth or towel in a rubbing motion to a relatively small area, and then immediately wipe it off with another clean, dry towel before the liquid evaporates.

If you're repainting a vehicle that still has paint on it, then this stage is made all the more important, especially if it might have any traces of wax on the surface.

It would certainly be a wise move to wash the car with detergent and water to begin with.

Then use wax & grease remover on all painted surfaces or surfaces to be painted, including door jambs, after you have stripped the car of trim but before you start sanding, after all sanding and priming and just before you're ready to shoot your final coat of sealer or first coat of paint, degrease the whole car again.

Again, the use of wax & grease remover is clearly demonstrated in 'How to Paint a Car' - Part 1.


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 make a start on the topic of Bodywork.

Happy Painting!

Chris Curwen & Dave Gage
www.LearnAutoPainting.com