Build Log: May 6, 2013

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Last time, I was block sanding the high build primer coat. This is a long and tedious process for someone who doesnít do it a lot. I really wanted to make sure that the body was nice and straight, and this is really the last chance to do that. In order to block sand a body with as many curves as a Cobra, you need a large assortment of blocks:

After I thought all of the block sanding was complete, I did another very thorough inspection with raking light. Any deep scratches, pinholes or other flaws are easier to see this way. Even after going on a pinhole hunt at least two times already, I still ended up finding some:

If you look closely, you can see the pinhole just above the tape. I found two or three more of those. I filled all of them with glazing, and did one last inspection.

Finally, I declared the car ready for paint.

I should take a moment to describe my expectations for paint. Some guys spend $10,000 or more on paint and rightfully expect a show car finish. I am clearly not an experienced painter and I recognize that my paint job wonít be as good as the $10,000 one. Having said that, I want to produce the best paint job possible considering that I am an amateur doing this in my shop. I will be happy with a 3-foot paint job. Meaning that the flaws will only be noticable if youíre closer than 3 feet. Iím hoping that my careful preparation and seemingly endless body work will improve on that expectation. Iím pretty sure that I have read everything on the internet about painting cars. Nobody can say I didnít research the process.

Before paint I needed to apply a sealer. This is a two-part primer that serves several purposes. First, since it is in the same paint family as the base coat and clear coat, I can have some confidence that I will get good paint adhesion. Second, the high-build primer is fairly porous, it would suck up some of the base coat, requiring more coats for hiding. Finally, the sealer provides a color base that completely covers the multiple colors of the high-build primer and the gel coat that showed through in some places.

The sealer I chose was PPG DPLF in red oxide color.

For the high-build primer, I used my cheap Home Depot gun, for which I bored the air cap to 2mm in order to handle the think primer. For the sealer, PPG recommends a 1.4mm tip, so I could use my much better DeVilbiss GFG 670 gun. The tech sheet calls for two coats and thatís what I did:

If there are any flaws in the body work, they will start to become very apparent as the painting process progresses. I was keeping my fingers crossed.

Now it was time for the base coat. For this, I used PPG Deltron DBC.

This got shot with the DeVilbiss gun with a 1.2mm tip. The tech sheet calls for a separate activator (DCX57) but everything I have read says that I can use the same activator as the clear (DCX61). That saved me the bother of buying a separate bottle of activator just to use 5 or 6 capfuls.

The color went on very nicely. I applied three coats in total. I probably could have gotten away with two coats, but I had plenty of paint and I didnít want to be surprised by thin spots:

Wow. Things are starting to look different. The color went on with no trouble. The tech sheet called for 10 to 15 minutes flash time between coats. I allowed 15 minutes.

Once all of the parts had color, it was time for the tough part - shooting the clear coat. Before we get to that, though, itís probably worth talking about safety for a moment. These paints, and particularly the clear coat, contain some very nasty solvents, and in the confined spaces of a booth when spraying large components, an air purifying respirator is simply not enough. I could get away with it when painting the engine bay panels, since the time spraying was actually pretty short. But for these large pieces, I will spend too much time in the booth putting too much vapor in the air to feel comfortable with an APR. So, I bought the cheapest supplied air respirator that I could find:

The words ďcheapestĒ and ďrespiratorĒ wouldnít seem to go together, but in actual fact, the Breathe-Cool is a pretty nice quality unit. Letís face it, a supplied air respirator is simply an air pump, a hose, and something that covers your face to deliver the air. The reason that the Breathe-Cool unit is inexpensive is because it is not NOISH approved. So, if your business is operating a respiratory protection program, you would not be able to use it. I have no such constraint. I just need an air pump that I can locate in clean air that can deliver enough air to me while in the booth. This particular model comes with a 75-foot hose and a bump cap and visor:

I tested it thoroughly and it delivers plenty of air to keep the ethyl-methyl-nasty out of my lungs. I bought a couple of Tyvek coverall suits, and I had plenty of nitrile gloves to complete the ensemble.

So, on to the clear. I used PPG Concept DCU 2021 clear:

For the clear, I used the DeVilbiss gun with the 1.4mm tip put back on. It is also worth commenting on the reducer. I chose the DT870, which is a middle temperature range (65 to 75 degrees). I can fairly easily keep my shop in that range as long as it isnít too cold or hot outside.

The clear coat is the toughest to shoot. The primer and color are both very forgiving. They flash very quickly, go on with a thin film and are very resistant to runs and sags. Clear, on the other hand, will run, sag, orange peel, etc. at the bat of an eyelash. Needless to say, I was a bit intimidated. But, with a 24-hour window to put clear over the color, I had no time to wring my hands.

I suppose it is a good thing that the hardest layer to apply also comes last. The three coats of Slick Sand, two coats of sealer and 3 coats of color gave me some opportunity to refine my gun technique. I was very conscious of this opportunity and worked very hard to plan the spray sequence, maintain gun distance and keep my body and hoses out of the paint. All of that apparently paid off, because the clear went on very nicely. There are a bunch of pics to follow - some with flash and some without to show how the paint shows itself in different light. You can see how nice and flat the clear laid down in the reflection on the doors:

Of course, runs are almost inevitable...though this looks like the only one.

Some pics of the trunk deck:

Once again, you can see how nicely the clear laid down, and so far the body is showing to be nicely straight. Those many hours of body work look like they might be paying off.

A few more pics in different light. First with flash:

And without:

With Flash:


With flash:

And without:

With flash:

And without:

One final picture of note. It seems like no matter how hard the backyard mechanic tried to create a sterile paint environment, the backyard always seems to find its way in:

This insect somehow managed to embed itself in the third coat of clear. There should be enough clear underneath to sand him out in the cut-and-buff process, which comes next...

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