An egg wash or release agent sprayer uses roughly 50 to 150 l/min depending on the nozzle, usually at a pressure of 2 to 4 bar at the gun. Two spraying stations and the rest of a bakehouse sit comfortably on a 7.5 kW 4-in-1 screw compressor such as the K 75, which delivers 1.1 m³/min at 8 bar. The tricky part is not the flow but the cleanliness of the air: it carries the product onto the dough or the tin, and it is filtered as close to the spray gun as possible.
The air demand of the whole bakery is covered on our page on the compressor for bakeries and patisseries. Here we focus on spraying.
What is air used for in egg washing and tin release?
There are three ways to spray in bread and viennoiserie production:
- the gravity cup spray gun, similar to a low-pressure paint gun: the air atomises the egg wash or oil and projects it onto the products;
- the pressure-tank sprayer, where the air pushes the liquid towards a nozzle;
- the spray bar on a conveyor or a tin greaser, with several nozzles controlled by solenoid valves.
In all three cases, the air touches the sprayed product, then the dough or the tin. That makes it a station with indirect product contact, which needs more than the air used for cylinders.
On the product side, egg wash is delicate: it is kept chilled and must not sit lukewarm in the cup. Release agent is often an oil or an emulsion, and its mist settles everywhere around the station.
What flow and pressure does a sprayer need?
The values below are typical, for guidance only; the sprayer's manual is the reference.
| Sprayer | Consumption | Pressure at the gun |
|---|---|---|
| Low-pressure gravity cup egg wash gun | 50 to 120 l/min | 1.5 to 3 bar |
| Manual release agent sprayer | 60 to 150 l/min | 2 to 4 bar |
| Release agent spray bar, per nozzle | 20 to 50 l/min | 2 to 4 bar |
The compressor pressure, set at around 7 to 8 bar, is well above the gun pressure. A pressure regulator with gauge, fitted just before the sprayer, brings the pressure down to the value in the manual. More pressure does not do a better job: the mist drifts off the trays, you use more product and you grease the floor.
The step-by-step calculation for two spraying stations
Example of a bakery and viennoiserie business that egg-washes by hand and greases its tins on a small spray bar (guide values):
- Egg wash spray gun: 80 l/min.
- Release agent spray bar with 4 nozzles: 4 × 30 = 120 l/min.
- Divider and moulder cylinders: 60 l/min.
- Bagging machine: 60 l/min.
- Total: 80 + 120 + 60 + 60 = 320 l/min.
- Safety margin of 25%: 320 × 1.25 = 400 l/min.
- Expansion margin of 20%: 400 × 1.2 = 480 l/min.
The K 75 delivers 1,100 l/min at 8 bar, so it covers this demand with plenty in reserve. A viennoiserie line with several spray bars and an automatic sheeter may need the K 110, 1.7 m³/min at 8 bar. Spraying is continuous use for as long as the gun is open: count it at 100%, not at half like a blow gun.
Which filtration for egg wash air?
Our compressors are oil-lubricated. On the K series, the built-in refrigerated dryer and filtration remove most of the water, particles and oil aerosols. For air that touches the dough, you add a stage at the station:
- a coalescing fine filter, which stops fine droplets of oil and water;
- an activated carbon filter behind it, which captures oil vapour and odours;
- the pressure regulator after the filters, just before the spray gun.
The fine filters are chosen for at least the flow of the station, margin included: a filter that is too small makes the pressure drop at the gun. The air class to aim for under ISO 8573-1 is set with our technicians and the sprayer manufacturer. Our article compressed air in contact with dough, which filtration explains the method, and our article on fine filters describes the role of each element.
The traps specific to spraying in a bakery
- Oil mist. Sprayed release agent falls back onto the floor, the machines and the walls. Spray in a dedicated area, set the pressure as low as the job allows and provide extraction if the spray bar runs for long periods. A greasy floor is a slippery floor.
- A blocked nozzle. Egg wash that is too thick or oil that is too cold blocks the nozzle. People turn the pressure up to compensate and the spray pattern becomes uneven. Clean the gun after each production run, as the manual says.
- Water in the air. Humid air spits droplets that mark the egg wash. The refrigerated dryer of the K series deals with this; on a standalone compressor you have to add one. Our guide to the pressure dew point explains why.
- The forgotten filter. A saturated filter element no longer protects the product. Note its replacement date and change it when its manufacturer says so.
- The same hose for everything. Do not connect the sprayer to the hose used to blow away dust or pump up a trolley tyre: it carries dirt back into the gun. Keep a clean hose for the station.
- The blow gun for drying. Do not dry a floured tray or a tin with the blow gun: the flour flies up and forms a combustible cloud.
The techniques of a low-pressure spray gun are close to those of paint spraying. Our article on the HVLP spray gun explains how to read the consumption of this type of gun.
Enter your stations in the configurator, or send us your sprayer's manual with a quote request: we size the compressor and the filtration for the station with you.
For your trade: Air compressor for bakeries, patisseries and viennoiserie.