688 Section 5 Refinishing Copyright Goodheart-Willcox Co., Inc. Overlap When painting, each stroke should overlap the previous stroke by 50%. See Figure 28-23. Overlap is the amount of fan that is sprayed over the previous stroke. Overlap ensures the smooth blending of paint by covering half of the previous stroke with the following stroke. Usually there is one stroke from right to left and one stroke from left to right. Two-stroke coverage ensures that the entire surface receives enough paint. Each portion of the panel is covered by two strokes. Proper overlap technique requires practice. The technician should aim the spray gun so the center of the spray pattern hits the edge of the previous stroke. This overlapping technique is repeated until the entire panel is coated. A 75% overlap means that each stroke covers 3/4 of the previous stroke. This method applies more paint to the surface than a standard 50% overlap. Stroke The movement of the gun from one end of the panel to the other is called stroke. To make an I-stroke, the trigger is pulled at the beginning of each stroke and released at the end. See Figure 28-24. Blending calls for a modification of the I-stroke called the J-stroke. Blending is a technique used to hide a paint edge. To make a J-stroke, the spray gun is held so it points away from the area that will not be painted and is toward the area that will be painted. See Figure 28-25. When making a J-stroke, the spray gun is triggered as it is moved toward the panel. During the stroke, the painter orients the spray gun perpendicular to the panel by wrist rotation. At the very end of the return stroke, the painter bends the wrist and turns the gun away from the area that will not be painted and triggers the gun off. The purpose of a J-stroke is to prevent dry overspray at the edge of a blend. By pointing the spray gun toward the spray area and away from the area that will not be painted, dry overspray is minimized. Dry overspray makes a blend obvious, the exact opposite of what a blend should be. A C-stroke is used to blend waterborne basecoat. Aim the center of the C-stroke at the edge of the last coat of basecoat. The wrist is rapidly rotated and the stroke is always perpendicular to the crown of the panel. The trigger is held down, and not released, while the spray gun is moved along the paint edge. J-Stroke Surface Trigger ON here Trigger OFF No paint here Minimal overspay here Spray gun tilts away from area that will not be painted, on the next stroke. Paint application Goodheart-Willcox Publisher Figure 28-25. The J-stroke is used in blending. Bending the wrist prevents overspray on the blended area. First stroke (Notice how 1/2 fan is above panel) Fan pattern Third stroke The middle of the fan pattern is aimed at the edge of the previous stroke 50% Overlap Second stroke Goodheart-Willcox Publisher Figure 28-23. In a 50% overlap, the next coat covers half of the previous coat. I-Stroke Surface Paint Trigger application OFF Trigger ON Consistent distance from panel to gun for entire stroke. Goodheart-Willcox Publisher Figure 28-24. The I-stroke is used in panel painting. Goodheart-Willcox Publisher Figure 28-22. A painter can practice maintaining a consistent distance by taping a paint stick of the correct length to the spray gun.