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Old 02-03-2019, 10:50 AM   #101
7TRoadster
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Spray Body Jams and Recesses

Read and follow the label on the can for best spraying conditions, temperature, humidity, mix ratios, etc. Match those conditions as closely as possible. Use the correct temperature reducer, there are three; fast, mid-temp and slow. Fast is used in the cooler temperature ranges as the solvent evaporates quicker reducing the time when paint sits on the car wet. This reduces tendencies for runs and sags. Mid-temp is about the best all around reducer. Slow is for the warmer temperature range where you need the solvent to evaporate slowly so the paint has time to flow out flat before the solvent evaporates.

Put on the shoot suit, turn up the fans, wet the floor of the booth, if you have access to a down flow booth this isn't necessary, if not wet dust on the floor will billow up when you're spraying the lower sections of the car. Even though your just spraying the jams and recesses today, wipe the whole car down with a tack rag including jams and recesses. This sticky cheese cloth will pick up any dust and lint that settled on it.

Mix the paint, ratio on the can indicates 2:1 with reducer. Only mix what you plan to use, in this case a pint after mixing will be enough. Stir it up well and using a paint filter pour the paint into the paint cup. For jams and recesses use a very short swing, remember the gun has to be moving when paint is spraying. Tight spots like the doors hinge pocket get a super brief pst, pst, pst, of paint as your wrist moves the gun back and forth only a couple of inches. You want base coat to go on dry, especially with metallics, so cut the paint delivery back on the gun to just above minimal levels. Spray with a separation distance of about 12-14" and as indicated the gun must be moving when your applying paint.

Open the door all the way and spray as much as you can of the forward jam and hinge pocket. Paint the bottom and rear of the door, door sill and finally the body jam. Paint the inside of the fender lips, rear window edges, inside the marker light recesses, tail lights, up under the license plate area, t-top jams hood jams, hood edges and around the grille openings. Anyplace that is hard to reach or at an awkward angle should be considered, I painted the headlight edges and side vents too. What I am trying to accomplish is to spray the areas that are hard to spray, the ones that require the gun to be at oblique or odd angles to get coverage. These are the areas where runs and sags are likely to happen, the last thing you want when spraying the flatter panels of the body.

Spray on a light first coat, this is called a tack coat, the intent is to get only enough paint on the car to make the surface sticky. This first coat will flash off in about 10 minutes. Apply a thicker second coat and allow that to flash off (15 minutes). Apply your final full coat and allow that to flash off. Flash times (time between coats) vary, read the paint can. For solid base coat colors this coverage should be sufficient for all but the lighter pastel type colors, for those add another coat.

For the final coat of metallic base paint only you're going to spray from 18-24" and fog the final layer of color on there. Try to come at it from as many odd angles and patterns as you can, keep it dry. Some areas will be limited but do the best you can. This will even out the metallics and eliminate the potential for other problems associated with shooting metallics. Once you're done clean the gun and wait at least an hour for the base color to flash off, you want all the solvent out of the color before spraying clear over it.

Mix the clear at 2:1, high solids clears tend not to flow out as well as expected. I usually add 10%-15% reducer to the clear depending on temperature, 15% on warmer days. This allows the clear to flow out better. Mix about the same amount of clear as you did base coat. Strain it into the gun. Apply the light first tack coat, only light coverage is desired. It will flash off in about 15 minutes. Spray the first full double wet coat, wait 1/2 hour, spray second full double wet coat. This will be sufficient clear for jams and recesses. Clean the gun. Clear needs more flash time, as you build coats extend the flash time. The curing of clear is a chemical reaction between clear and catalyst. This reaction gives off gas, if you spray over a coat that is still degassing it results in tiny pin holes the gas makes as it continues to escape. When adding a third coat of clear, wait 45-60 minutes depending on temperature.


Tips:

Raising the car on blocks or jack stands can help you keep the gun square in the lower hard to reach areas. Another trick to do this is to rotate the cap on the gun 90* so the fan is horizontal, change your spray sweep to up and down.

Do not allow any material to dry in the gun, clean it promptly and thoroughly, remove the cap and tip, a short bristle brush works great, passages can be cleaned with a cleaning brush set from the paint store for just a few bucks.

Obviously you're going to have some over spray onto body panels. It's very common to get a run or sag either in the color or clear. Use a piece of 3/4" masking tape, place between thumb and forefinger sticky side out and place that right over the excess paint and pull it back off the car. This will lift enough material to make it easy to block flat again. Let what ever paint/clear is left to flow back out.

Follow the flash times, if you get impatient at this point you'll be taking steps backwards.
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