Here is a quick look at our 1969 GTO Judge
project's body after its first refinish process. This consisted of (after countless hours of block-sanding and wet sanding) applying a light grey epoxy sealer, then 3 coats of PPG Carousel Red, followed with two coats of PPG Global D8152 'Performance+Glamour' Clear. Once painted, it was baked for an hour at 140 degrees.
Note: The base color was wetsanded with 800 grit paper between the first and second coats to remove any errant dust particles that inevitably seem to find there way into the first coat or two. After that sanding, the remaining coats remain very "clean".
The next step, tomorrow, is to block-sand the entire body with 600/800 grit wetsanding paper, then apply 4 additional coats of the same Global clear (called Flow-coats). Then, again, another bake cycle, and it is done...for now. We do the clear in two steps because we want a higher millage than the products will allow for in one application; therefore, we cannot apply it all at once. The urethane products won't dry properly if too many coats are applied at once. Also, the second clearing produces a much "slicker" finish with less texture (orange peel), which leads to easier wetsanding and polishing.
We will come back at some point the near future and take the entire car through our wetsanding and polishing process, which will produce the mile-deep finish we strive for in all of our projects. This is where the real magic happens, and is why so much effort is put into the bodywork and block-sanding phases.
Useless paint trivia
: the baking cycle, despite what many people think, doesn't make the paint any better, harder or more durable. It simply accelerates the drying process by forcing solvents out of the film build and accelerating the catalyzation (aka: hardening) of the applied product. Some clears are engineered to "need" to be baked for production reasons, but in the end, the reslulting final product is the same whether baked or dried by normal evaporation at ambient temperature. At PAINTHOUSE
, we use baking for a different reason in most cases. We purposely put the part(s), and all the materials used on it, through a bake cycle several times during the bodywork and blocksanding/priming phases, then, once it has cooled down, we have gotten the materials (filler, primers, etc) to expand then contract. This removes solvents and causes the "shrinkage" factor to be much lower down the road versus rushing through all the steps, with each component never fully drying (it can take weeks or more for body filler, primers, sealers, paints and clears to completely dry). This is one of the reasons these restorations/custom builds can take so long. The heated booth is also good for pre-heating the surface temp of the item. If it is below 50º F, these urethane materials just don't want to harden properly. Believe it or not, there are many days here in Houston where the ambient temperature is at, or below, that level. A heated booth is a versatile, multi-faceted tool that I could not do without in my business.
Now you know more than you ever wanted to know about the refinish and baking processes. Feel free to use it to impress your family and friends at the next big get-together.
Until next time,
Sunday, April 10, 2011