Airless Sprayer Glossary of Terms

Here is our glossary of some common terminology regularly used with airless paint sprayers and within the airless spray painting industry in general. Many of these terms you may know already, but hopefully you can increase your airless vocabulary with this list of meanings.


Refers to spray equipment which uses high pressure, rather than air, to atomize coating materials for spray-on application.
Airless Sprayer
Normally a piece of equipment containing a high pressure pump powered by gas, electricity or gas-hydraulic for spraying liquid materials and coatings onto a surface.
Shop Airless Sprayers
When a liquid is broken apart into minute particles or fine spray.
When the paint spray fan reaches the end of a surface, such as an outside corner, and the fan continues beyond the surface, paint is "blown-by" the target surface in a cloud of droplets
Bounce-back / Back-spray
when the painter directs the airless spray fan at the surface, sometimes the droplets will rebound from the surface. This is the result of excessive pressure and excessive velocity beyond the amount needed to atomize the coating.
A trademarked name of a patented pressure actuated valve made by Graco that shuts of the paint supply to the spay tip that is on an extension pole to keep "spitting" from happening after releasing the trigger.
Purchase CleanShot Valve
Dead band
This is the area in time between pulling the trigger on the spray gun and the pump staring to pump again. Most mechanical pressure controls allow about a 300 psi drop in pressure before turning the pump on. Graco's SmartControl is an electronic pressure control that reduces this pressure drop to about 50psi. The second generation, Smart Control 2.0, reduces this even further to a near zero dead band.
The dead-band results in a fading spray fan followed by a burst to the full, set pressure. The dead-band is more noticeable when spraying thinner materials and/or at lower pressures. The EPC gives a more consistent and even fan pattern and eliminates a few moving parts which can result in less long-term maintenance costs.
A pump design that uses a circular or oblong flexible synthetic membrane, sealed at its outer edges and connected in its middle to a reciprocating rod (or motor rod) or pulsating hydraulic fluid. As the membrane moves in response to the rod or hydraulic fluid, fluid is loaded and dispensed through the check valves.
Electronic Pressure Control
A pressure regulation device that uses electronic components, rather than electric or mechanical components, to provide precise pressure regulation.
This is the spray itself, the shape of the spray.
Fan Size
The spray fan size is normally measured top-to-bottom and 12" from the surface being sprayed. The fourth digit in a Graco spray tip part number is usually the one that determines fan size when multiplied by 2, example; a LTX413 tip would have an 8" fan.
See Also; Tip Sizes, Tip Sizing, Tips on Tips
Refers to clear and gloss finishes such as lacquer or polyurethane on cabinets, banisters, furniture etc.
More about Fine Finish tips
Fine-Finish Tip
A specially designed tip for better atomization at low pressures. Graco's RAC X Fine Finish SwitchTips have a pre-orifice for finer atomization.
Acronym for Gallons Per Minute.
Inlet Ball
The ball portion of the inlet valve of the fluid section of an airless sprayer that acts as a check valve when suctioning paint. Normally on the lower / bottom end.
Inlet Tube
The tube that goes into the material to be sprayed that leads to the inlet side of the pump / fluid section.
See Also: Return Tube
Mil Build
The thickness of the coating during or after spraying.
The one-piece seal that goes between the Graco RAC tip guard and the tip.
The hole in the tip that the material passes through on its way to the surface being sprayed. The size of the orifice regulates the amount of material that passes through thereby controlling the amount of product dispersed. Also See: Fan
When paint or other coatings are atomized, the tiny droplets form a cloud that may go beyond the edges of anything being sprayed.
The material used to make a liquid tight seal
Pole Gun
A spray gun on an extension pole used to spray in hard to reach places. Also used in lieu of standing on scaffolding.
Pressure Control
The device on an airless sprayer that regulates the pressure of material output to the hose and spray gun.
Pressure Roller
Similar to a conventional paint roller but designed to attach to an airless hose or gun and deliver, at a low pressure, a coating through the roller cover thereby eliminating the need to dip the roller into a tray of coating. Shop pressure rollers
Pressure Switch
See: Pressure Control
This is the act of getting the material to be sprayed into the pump and removing air from the system in preparation to spray.
  • 1. The entire sprayer
  • 2. The fluid section of the sprayer
Pump Armor
A pump preserver by Graco which is used after thoroughly cleaning an airless sprayer to help protect the fluid-section from rusting / deteriorating while it is not in use. Purchase Pump Armor
RAC (IV, 5, X)
RAC is an acronym for Reverse-A-Clean, the ability to spin the tip at a 180 rotation to blow out a clogged tip.
RAC IV, 5, and X refers to the different types of spray tips.
Also See: Tip Sizes and Tip Sizing
Return Tube
The smaller tube on a airless paint sprayer that returns material to the container during the priming of the pump.
When spraying a textured surface the pattern might not fully coat the entire surface. Shadows are overcome by spraying the surface from the opposite direction filling in the shadowed areas.
An advanced microprocessor on Graco sprayers control delivers:
  • A consistent spray fan at all spraying pressures.
  • Zero dead band (no pulsating, steady consistent pressure) at lower spraying pressure, ideal for fine finish spraying.
  • Graco's WatchDog™ System automatically shuts sprayer off when paint supply bucket is empty to prevent sprayer damage
Spray Fan
The pattern of spray created by the airless sprayer and tip. Usually long and narrow in shape with a new, average sized tip. The fan may become an oblong oval or oval after tip wear and even a circle after extreme wear. See fan size.
More about airless sprayer tip sizing.
Spray Tip
The final piece of the spray equipment that the coating material passes through and normally causing atomization which creates a spray from the liquid. Different tip orifices mixed with various pressures atomize the material in numerous ways creating a wide range application scenarios. More about sprayer tip sizes
Throat Seal Liquid
Liquid compound that is placed in a small cup that surrounds the top of the pump rod to keep the packings wet and lubricated and also keeps overspray, that may come in contact with the rod, from sticking to it and causing damage to the packings. Buy Throat Seal Liquid
Tip Extension
A tubular extension that attaches to the sprayer gun in place of the tip guard. The tip guard then attaches to the end of the extension. Available in many lengths and used to paint (average height) ceilings without a ladder, spraying decks without bending over, under eves etc.. Being away from the tip also reduces the amount of paint you get in your face and on yourself! Shop Tip Extensions
Avoid poison oak at all times! Don't eat yellow snow. ;-) See: Spray Tip
Tip Guard
The piece attached to the spray gun around the tip to help prevent direct contact with the tip thereby preventing injection injuries. See Also: Airless Safety
See: Throat Seal Liquid
A measurement of the resistance of a liquid to deform and/or break / shear apart under stress. Most people think of this as thickness or thinness. There are many ways to measure viscosity, The Zahn Cup is probably the most recognized device and method as well as accurate.
Whip Hose
A short, usually smaller diameter section of high-pressure airless hose that goes between the spray gun and the main hose to provide more flexibility and control and also reducing hand fatigue. Shop Whip Hoses
Zahn Cup
Device used to measure viscosity of a liquid. Widely used in the paint industry to keep coatings consistent between batches being manufactured as well as for measuring materials that are being thinned for various reasons.