aIR CAP PRESSURE GAUGES ALLOW THE REFINISH TECHNICIAN TO: aDJUST THE INLET AIR PRESSURE TO THE SPRAY GUN FOR THE PROPER AIR CAP PRESSURE. This problem occurs when tiny air bubbles rise to the surface of the paint and pop, leaving craters behind. Grit refers to the problem of solid particles of varying sizes being embedded in the surface of your paint. Technician A says that a magnetic thermometer may be used. Pinholes occur when body fillers contain air bubbles that are then exposed while you sand the area, leaving small holes behind in the surface. It is possible to fix this issue by allowing it to cure and then sanding and re-spraying. The easy way to avoid this is to make certain that you use a wax and grease remover while you are preparing to paint. This issue is usually caused by the insufficient draft angle of the product, or that the core drags the product with a larger force than the cavity, causing the cavity to be scratched. Technician B says that the term curing is used to describe the evaporation of solvents from the material. Technician A says that when mixing refinishing materials, a nylon paint strainer should be used. Nothing changed. This happens when the gloss or shine of the finish dulls as it dries. It can be caused by many different things, including using a spray pattern that is not balanced, tilting the gun, over-thinning or spraying on your clearcoat before the basecoat has completely dried. The amount of volume capable of being delivered by a compressed air system is measured using what? The most likely cause is some sort of contamination, either in the paint or on the substrate, that prevents a proper bond between the paint and substrate. Technician A says that an improper hose length may cause a pressure drop in the air line. When you lose adhesion between your paint and its substrate, sections of the color may separate away. The draft angle of the mold core is not big enough – increase the draft. They result from moisture that is trapped under the surface of the paint. This results from the improper mixing of your hardener with the filler. A bad spray pattern or timing error is likely the reason behind the deterioration of the edge of this piston crown. thank you. Share via: Facebook Twitter LinkedIn Print By Clifford K. Schoff, Schoff Associates Spraying is the worst possible way to apply automotive coatings if minimization of surface defects is desired, but it is the only way to obtain the gloss, color effects, and outstanding appearance that car buyers demand. Forget Powder Coating, Think Spray Chrome! In areas with high humidity levels, blushing can happen when the evaporation of the solvent reduces the surface temperature below the dew point. This may be repaired by allowing your stained topcoat to fully cure. There are many different causes, but it often results when you don’t allow the undercoat to adequately dry or cure. How much reducer is required? It is also called as hard spot. If you use too much of the hardener, pinholing is even likelier to occur. Poor Spray Pattern. With this problem, cracks of varying lengths form in your finish. Required fields are marked *. They also occur when the plastic flows through sections with varying wall thickness, or when the injection speed is too low causing the plastic to solidify at different speeds. b. If the defect is inverted, obstruction is on the air cap. It can also happen when you are painting over a cracked surface or if you use too much hardener. Breathing air for supplied air breathing equipment must be: Technician A says that a paint suit is designed to prevent the refinish technician from exposure to overspray. 2. To avoid this, make certain that your spray gun is adjusted properly, use the correct air pressure setting and keep your gun an appropriate distance away from the surface. Some do-it-yourself types enjoy trying their hands at automotive painting. can you help please ? After painting some small parts , as the paint dried it “rain bowed” obvious oil was present.changed oil seperator cleaned gun and air hose. These are cracks that sometimes appear in topcoats. Who is right? Other causes are caustic etch spray or accidental spillage of caustic chemicals. Your email address will not be published. Who is right? This can also be caused by excess solvent in the paint. It can also happen if you are using a can of old paint. It can be caused by many different things, including using a spray pattern that is not balanced, tilting the gun, over-thinning or spraying on your clearcoat before the basecoat has completely dried. Technician B says that a vacuum is used to draw the material up a siphon feed spray gun. Grit. Who is right? A particulate counter is designed to measure: To minimize pressure and flow drop in an air hose: Six ounces of primer must be reduced 50%. Uncontrolled hypertension is most likely to cause ischemia and loss of function in the: a. kidneys, brain, and retinas of the eye. This can happen when the paint or primer is not strained or stirred properly. Then, spray a sealer over it and reapply the color. Also known as edge mapping, this paint problem results from solvents in topcoats penetrating through areas of the undercoats. the paint that was put on looks yellow as a base think etch primer, then grey primer then colour, . To achieve good painting work, applicators and site supervisors should understand the causes and preventive measures of common defects that occur at Like dulling, this may result from several different causes. Who is right. Technician B says that a hose with less than 3/8" inside diameter may cause a pressure drop in the air line. 3.0 INSPECTION PROCEDURES. Finally took a small brush and right out of the can the paint “ rainbowed” … so did it get contaminated when mixed? What controls overspray removal and dust most effectively? Formation of dull patches on the painted surface is known as blooming.
this spray pattern defect is most likely caused by: