Airless spray paint fan pattern tailing.
Tailing when spraying with an airless paint sprayer is a phenomena where two distinct heavier lines of paint appear on either edge of the paint spray pattern. Inside these heavier edge lines there may be no paint or very little paint before the spray pattern reappears and often becomes heavier towards the center.
Tailing with airless paint sprayers can be the result of several different factors or a combination of factors.
One common cause of tailing with an airless paint sprayer is not enough pressure. This could mean that the airless sprayer is malfunctioning and not developing enough pressure or that the paint being sprayed requires much more pressure than the airless sprayer, which is operating as designed, is capable of delivering.
Over the years I have seen tailing occur when spraying a certain brand and type of paint where it had not occurred with that brand and type of paint previously. This could be a result of fluctuations in manufacture where viscosities or other factors have moved slightly or where rapid temperature changes have occurred, usually towards colder temperature such as in winter.
A quick test to determine if it is the paint causing the two heavier lines either side of your spray pattern tailing effect or a fault with the airless paint sprayer causing the tailing effect is to try spraying a different brand or type of paint to see if it still tails. Success with a different brand does not prove there is a problem with the former brand as these issues can occur with any brand from time to time.
If testing your airless spray paint machine with a different paint eliminates the spray pattern tailing effect some options to try which may assist in reducing or eliminating the tailing effect with the paint at fault could be to warm the paint if it is cold, try thinning the paint slightly, some painting contractors have success by adding methylated spirits to water-based paints and a product from the Flood company called Floetrol Acrylic Paint Conditioner will often eliminate tailing in airless spray paint fan patterns.
If your airless spray paint machine tails with other types of paint as well try several other airless spray tips to see if there is any difference, check the actual pressure while your airless spray machine is spraying and if there is a huge pressure drop check that the airless spray tip being used is not too large for the actual airless spray machine model. Each airless spray machine manufacturer specifies a maximum airless spray tip size that can be used with each model of airless sprayer.
Should all the above options not reduce or eliminate the tailing and airless spraying pressures appears to be too low while spraying with the airless sprayer, follow the pump checking procedures for your airless pump to identify any faulty valves or other components.
If the machine is operating at pressures close to specifications and tailing is still occurring in the spray pattern refer to the paint manufacturer for recommended actual spraying pressures and recommended spray painting equipment for that paint.
I have seen numerous paints especially acrylic paints being sprayed many times over the years through an airless paint sprayer with a faint tail evident on either edge of the spray pattern which has not been affecting the final job. If you are able to spray at a pressure at or just above where tailing in the spray pattern is overcome then it is highly likely that the optimal spraying pressure for your paint and airless spray machine is achieved. This will result in reduced paint over spray and reduced wear to your airless spray pump, airless spray gun and airless spray tip