Paint booth glossary
Paint booth terms in plain English
39 words you'll hear from painters and technicians, explained simply. Jump to a letter below, or follow the links to our guides for more detail.
A
- Air makeup unit (AMU)
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The unit that pulls in outside air, filters it and, on heated booths, warms it to replace the air the booth exhausts. If it struggles, the booth can lose pressure or temperature.
Air makeup unit problems →
B
- Bake cycle (cure cycle)
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The part of the booth's operation after spraying when it heats up to a set temperature to cure the finish. Many booths also change how air moves during the bake.
Bake cycle problems → - Burner
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The gas-fired heater that warms booth air for spraying and baking. Burner, gas and ignition work is for a qualified technician only.
Booth heater and burner service →
C
- Ceiling filter (diffusion filter)
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The final filter in the booth ceiling, mostly on downdraft and semi-downdraft booths. It catches fine dust and spreads incoming air evenly over the work.
Choosing intake, ceiling and exhaust filters → - CFM (cubic feet per minute)
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A measure of how much air a fan moves, or how much air passes through the booth, in a minute.
- Color rendering (CRI)
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How true colors look under a light source compared with natural light, usually given as a number up to 100. Higher is better for color matching.
Booth lighting problems → - Control panel
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The panel that runs the booth: fans, heat, lights, modes and safety interlocks. Electrical faults here are for a qualified technician.
Control panel and electrical faults → - Crossdraft
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A booth where air comes in through filters at the front (often in the doors) and travels lengthwise past the work to exhaust filters in the back wall.
Downdraft vs. crossdraft vs. semi-downdraft →
D
- Damper
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An adjustable plate inside the ductwork that controls how much air flows. Dampers are used to balance booth pressure and to switch between spray and bake modes.
Paint booth damper problems → - Door seal (gasket)
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The rubber or foam strip around booth doors that keeps unfiltered shop air and dust from leaking in.
Door and seal repair signs → - Downdraft
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A booth where clean air enters through the ceiling and is pulled down past the work and out through a pit or floor grates. It keeps overspray moving away from the work.
Downdraft vs. crossdraft vs. semi-downdraft → - Ductwork
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The metal ducts that carry air into and out of the booth. Paint buildup inside exhaust ducts restricts airflow and adds fire risk.
Ductwork buildup and leaks →
E
- Exhaust filter
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The filter that catches overspray before air leaves the booth through the exhaust fan and stack. Loaded exhaust filters cut airflow and raise booth pressure.
Paint booth exhaust filters →
F
- Face velocity
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How fast air moves across the open face of a booth or through the work area, usually measured in feet per minute (fpm).
- Fan belt
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The belt that connects a motor to a fan. A worn or slipping belt quietly cuts airflow. Belts should only be serviced with the booth locked out, by a trained person.
Fans, motors and belts → - Filter loading
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Paint and dust building up in a filter as it works. The more a filter loads, the harder air has to push through it, and the higher the pressure reading climbs.
Understanding spray booth filters → - Filter monitoring
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Reading the pressure across booth filters continuously instead of checking a gauge by hand, so you know when filters are actually due.
Smart Filter Monitoring → - Flame rod (flame sensor)
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A metal rod that sits in the burner flame so the burner's safety control can confirm the flame is lit. If the flame can't be proven, the control shuts off the gas.
Burner won't ignite? → - Flash time
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The wait between coats, or before baking, that lets solvent or water evaporate from the paint. Cutting it short can trap solvent and cause defects.
Speed up cure times without defects → - Foot-candle (fc)
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A unit of light falling on a surface. One foot-candle is about 10.76 lux.
Booth lighting problems →
H
- HVLP (high volume, low pressure)
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A type of spray gun that uses more air at lower pressure so more paint lands on the part and less becomes overspray.
I
- In. w.c. (inches of water column)
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The unit booth gauges use for very small air-pressure differences. It's tiny: one pound per square inch equals about 27.7 in. w.c.
How to read a manometer → - Intake filter
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The first filter the outside air passes through, at the air makeup unit or booth intake. It catches outdoor dirt before air reaches the ceiling filters.
Spray booth intake filters → - Interlock
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A safety connection that stops one thing from running unless another is working. For example, preventing spraying unless the exhaust fan is running.
L
- Lockout/tagout (LOTO)
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Shutting off and locking out a machine's power so it can't start while someone works on it. Required before servicing fans, belts or electrical parts.
- Lux
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The metric unit of light falling on a surface. Booth lighting is often compared in lux or foot-candles.
Booth lighting problems →
M
- Manometer (pressure gauge)
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A gauge that shows a pressure difference, such as across a set of filters or between the booth and the shop. It reads in inches of water column (in. w.c.).
How to read a manometer → - Moisture separator (water trap)
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A device on the compressed-air line that collects water so it doesn't reach the spray gun. Drain it regularly.
Water in your air lines? →
N
- Negative pressure
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When the booth is at a lower pressure than the shop, so air is pulled in through every gap. In a closed booth that also pulls in dust.
Air pressure balance →
O
- Overspray
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Paint that misses the part and stays in the air. The booth's airflow and exhaust filters are there to carry it away and catch it.
P
- Paint arrestor
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Exhaust filter media designed to capture paint overspray before air leaves the booth.
Paint booth exhaust filters → - Plenum
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The open chamber above the ceiling filters (or behind a filter wall) where incoming air spreads out before it flows into the booth evenly.
Plenum and airflow distribution → - Positive pressure
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When the booth is at a slightly higher pressure than the shop, so air leaks out of gaps instead of in. Most closed booths are set slightly positive to keep dirt out.
Air pressure balance → - Pressure balance
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Setting the air coming in and the air going out so the booth sits at the right pressure. Done by adjusting dampers and fan speeds.
Why your booth is losing pressure →
S
- Semi-downdraft
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A booth where air enters through the ceiling near the front and flows down and back to exhaust filters low in the rear wall.
Downdraft vs. crossdraft vs. semi-downdraft → - Side-draft
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A booth where air enters through the ceiling and exits through exhaust filters low in the side walls instead of a floor pit.
Booth types explained → - Static pressure
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The resistance a fan works against to push or pull air through filters and ducts. Rising static pressure across a filter usually means it's loading up.
How to read a manometer →
T
- Transfer efficiency
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The share of paint that actually lands on the part rather than becoming overspray.
V
- VFD (variable frequency drive)
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An electronic drive that changes a motor's speed. On booths it lets fans run at different speeds for different modes and start smoothly.
Cut booth energy and gas costs →
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