For a glazing booth with one spray gun, a 5.5 kW screw compressor such as the S 55 (0.6 m³/min at 8 bar) is enough, provided an air receiver and a dryer are added. For two booths, or one booth plus blow guns, the K 75 is the simplest choice: 1.1 m³/min at 8 bar, with a 420 L air receiver, refrigerated dryer and filtration built in. Beyond three spray guns working together, move up to the K 110 (1.7 m³/min).
The air needs of the whole workshop, from the presses to pulse cleaning, are covered on our page compressor for ceramics and glazing. Here, we focus on the glazing booth.
How much air does a glaze spray gun use?
A glaze spray gun looks like a paint spray gun, with a larger nozzle to let through a glaze that is heavily loaded with solids. It uses air continuously as long as the operator holds the trigger, and the glazer often sprays without stopping throughout a whole batch of pieces.
As a guide, a glaze spray gun uses around 200 to 350 l/min, depending on the nozzle size, the spraying pressure and the type of gun. A high volume, low pressure (HVLP) gun tends towards the top of the range, at low pressure. Take the exact figure from the gun's manual: that is the number used in the calculation.
Do not rely on the average consumption over the day. In the booth, the gun is blowing almost all the time during a batch: count it at 100%, as our configurator does for tools in continuous use.
The step-by-step calculation
Step 1, the spray guns. Multiply the consumption of one gun by the number of guns spraying at the same time. Two booths, two glazers: two guns.
Step 2, the other uses. Add the blow gun used to dust off greenware just before glazing. It blows in bursts: count it at 50%.
Step 3, the safety margin. Add 25% for leaks, nozzle wear and network losses.
Step 4, the expansion margin. Add 20% for a future booth or a larger gun.
Example of a ceramics workshop with two booths (indicative figures, to be replaced with those from your manuals):
- 2 glaze spray guns at 300 l/min: 600 l/min
- 1 blow gun at 150 l/min, counted at 50%: 75 l/min
- total: 675 l/min
- with 25% safety: 675 × 1.25 = 844 l/min
- with 20% for expansion: 844 × 1.2 = 1,013 l/min, or about 1.0 m³/min (roughly 36 CFM)
The K 75 delivers 1,100 l/min at 8 bar: it covers this need. With a single booth, the same calculation gives (300 + 75) × 1.25 × 1.2 = 563 l/min, and the S 55 with its 600 l/min is enough.
Which model for how many booths?
| Installation | Need with margins | Recommended model |
|---|---|---|
| 1 booth, 1 spray gun, 1 blow gun | around 0.55 m³/min | S 55 + air receiver + dryer, or K 75 to have everything built in |
| 2 booths | around 1.0 m³/min | K 75, 1.1 m³/min at 8 bar |
| 3 booths, or a glazing line with spraying robots | around 1.5 m³/min | K 110, 1.7 m³/min at 8 bar |
| 4 booths or more, or glazing + presses | above 2 m³/min | K 150 or larger, to be calculated for the whole workshop |
All the models in the S and K series are variable speed. Between two batches of pieces, while the glazer reloads the booth, the compressor slows down instead of running off-load.
What pressure should you set for glazing?
Glaze is sprayed at low pressure, around 2 to 4 bar at the gun depending on the viscosity of the glaze slip and the nozzle. Too much pressure makes the glaze bounce back and creates overspray that settles all over the booth; too little gives large droplets and an uneven coat.
The compressor itself is set at around 7 to 8 bar. This reserve makes up for the losses in the network, the dryer and the filters, and keeps the pressure steady at the gun even when a blow gun is opened. Each booth gets its own regulator with a pressure gauge, set once and for all for the glaze in use. Write the setting on the booth: it is what gives the same thickness from one batch to the next.
Why does a 4-in-1 suit glazing so well?
Glazing does not forgive water or oil in the air. A drop of water dilutes the glaze and leaves a run; a trace of oil on the bisque makes the glaze crawl during firing. So, at the very least, you need a refrigerated dryer and filtration at the compressor outlet.
A 4-in-1 compressor brings all of this together on a single frame: compressor, air receiver, dryer and filtration. For a workshop without a technician, it guarantees treated air from the day it is commissioned. Our article 4-in-1 or standalone compressor compares the two options.
Our compressors are lubricated: it is the filtration at the outlet that holds back the oil carried over. Add a fine filter at the foot of each booth, just before the regulator. The air class under ISO 8573-1 is set with our technicians. The link between the air and glaze defects is covered in our article dry air and glaze defects.
Pitfalls specific to the glazing booth
- A hose that is too long or too narrow. A 15 m hose of small diameter makes the pressure drop at the gun. Bring the rigid pipework closer to the booth.
- The compressor in the booth. Glaze overspray and dust clog the air filter and the cooler. Install the compressor outside the workshop, in a clean, ventilated room protected from dust.
- Forgetting to drain. Without an automatic drain, water builds up in the air receiver and ends up at the gun.
- A blow gun on the same regulator. It makes the spray gun's pressure drop every time it is used. Give it its own outlet.
For the final choice, enter your booths in the configurator, then send us your spray guns' manuals with a quote request.
For your trade: Compressor for ceramics and glazing.