March 21, 2006

We've made serious progress on the full repaint of our client's very cool green 1962 190SL. Last month's article ended with the car being completely stripped of any paint after the application of a chemical stripper. What did not come off during this process, however, was the filler from 42 years of various spot repairs to the coachwork. In order to correctly prepare this car for paint, every trace of external material needs to be removed from the coachwork. The notion of a “bare metal” repaint is quite descriptive hence the preparation process continues until all you see is bare metal!

	Finally to bare metal. A thing of beauty!

Ok, so now we have a nice example of automotive sculpture, the iconic 50's era Mercedes SL glowing in all its silvery metal glory. There are some blemishes on this beautiful pure design and we need to get to work on them pronto.

Correcting the poorly repaired right front fender/headlight bucket area will be the most time consuming so we'll tackle that right away. The butt weld at the center of the fender is acceptable but the crudely repaired section just aft to the headlight bucket needs to be corrected. Cutting the entire wide loop of the old repair out of the fender would raise the risk of not being able to duplicate the nice curvature of this panel once we attempted to section new metal back in. So we'll handle this repair with a sequence of three new sections installed one after the other. This way we can retain the general shape of the panel. With these sections installed we have restored the general curvature of the fender and can complete the process with local grinding and working of the patches. Another issue with the old repair was the fact that the replacement headlight bucket was brazed to the repaired fender. Because paint materials adhere poorly to a brazed repair, the risk of paint materials lifting from the repaired area was quite high.

	New sections installed with old brazed section in foreground.

With the nose of this cool 190 now looking a bit more normal we work our way around the car correcting the miscellaneous funky repairs accumulated over the years. This entails correcting imperfections, subtle application of filler, sanding, priming and blocking. The block sanding process evens out any repairs, blending them with the natural curvature of the affected panel using narrow strips of sand paper attached to a 16” x 3” slightly flexible double handled sanding block. When you sight carefully down the sides of a newly painted car and see subtle waves in the panels, this usually indicates insufficient “blocking”, an absolutely critical step in the paint process. There will be plenty of additional blocking before this project is completed.

Block sanding any large panel surface.		Almost ready.		Key to excellent panel appearance, hours with the block sander.

Once we're happy with all our repairs and the basic panel integrity and curvature has been restored to the coachwork, it's time to apply two gallons of primer. And though we have removed all external items, we need to carefully mask the car to avoid blowing primer into the wheel arches, engine bay, trunk and undercarriage. The hood and deck lid will be primed off the car. Once the car is primed, we'll let it sit for about 2 weeks to allow all the materials we've applied to get happy together and do their thing with shrinking and such.

In the booth and ready for primer.		Primed and waiting for paint materials to cure and dry.		Right front fender looking much better now!

Now that we have a fully prepared and primed 190SL let's have a look at what it took to arrive at this point with regard to time and costs.

Materials: $1,200 (Standox paint products)

Man hours: 160

Labor costs: 160 x $75/per hour = $12,000.

Total cost to prepare and prime: $13,200

Hmmm, that's a few bucks. The right front fender mess consumed about 24 hours of that labor figure. If after stripping the car we found zero body repairs, the whole process would have been shortened by about 80 hours, a drastic change in cost. This is a prime example of how difficult it is to expect someone to accurately estimate this type of job without stripping the car to see what lies beneath. Poor prior body repairs can DOUBLE the time to prepare and paint a car!

Next month we'll have look at the final preparation before the application of color.