A Tale of “Tails”

Question:

I am the plant manager of a company that has recently installed an airless spray unit to take advantage of its cost savings because of the increase in transfer efficiency. We are getting a condition that my people described to me as “tails” in the spray pattern using our new painting equipment. Naturally, the tails are causing paint film defects. We read all the articles on airless spray painting hoping to learn how to eliminate these tails. The manufacturer’s representative told us that the problem does not exist and even if it did, he would not know what to do to eliminate it. What should have been a dream-come-true, i.e. cost savings, has now become a nightmare. Is there somewhere we can go for information or someone to tell us what steps to take to eliminate this “tails” problem? B.J.

Answer:

It sounds like someone was pulling your tail and you ended up chasing it. Perhaps the manufacturer’s representative is telling you the truth when he says that he does not recognize the problem. However, any responsible rep would refer a problem such as tails in a spray pattern or any other problem he doesn’t recognize to the spray equipment manufacturer. You may want to call the manufacturer yourself to get a definitive answer. I know he will help you solve the problem because his continuing business depends on satisfied customers.

Now, back to the tale of the tails. Tails in airless spraying is a well-known problem. They are caused by incomplete atomization of the liquid throughout the spray pattern resulting in a solid stream when paint that is too high in viscosity is sprayed. This generally occurs at the outside edges of the of the spray pattern fan. Tails can often be eliminated by reducing the paint’s viscosity by thinning with solvent or by heating using an in-line heater, possibly by raising the fluid pressure. Changing spray nozzles may also eliminate this problem. In this age of regulation, adding solvents to reduce viscosity is discouraged.