Spray guns painting Easter eggs

Hühnerhof Wiesengrund dyes millions of eggs each week, and its busiest time is Easter. However large quantities are also produced at other times of year since dyed eggs are such a popular choice for snacks or light meals. Supermarkets and discounters offer them ready-packaged, or they can be purchased loose in bakeries, butcher shops, and at farmers’ markets. 

Large dyeing plants use two different methods to add color to white eggs. Mottled effects are produced using a roll dyeing method, while spray dyeing achieves extremely uniform, higher-quality surfaces. “When it comes to colored eggs, you really eat with your eyes, even though the color doesn’t actually influence the taste. That’s why a flawless appearance is an important selling point. The quality standard by which the consumer measures all painted surfaces is set by the automotive industry, with its shiny high-gloss coatings. The same goes for dyed eggs,” explains Martin Wüst, Technical Director at Hühnerhof Wiesengrund. The company dye shop has around 100 spray guns, which lose alignment and therefore need to be manually readjusted. The egg’s white shell can show through if too little lacquer is applied, while too much lacquer can produce ugly streaks. Hühnerhof Wiesengrund therefore engaged integrator Eugen Fuchsberger GmbH & Co. KG to find a better solution in partnership with Dürr.

For the spray dyeing method, the eggs sit upright on small spindles. They are automatically passed in front of a rig with 30 spray guns, turned, and at the same time sprayed with a lacquer based on natural resin, alcohol, and food dyes using air atomization. The stroke frequency required for this is very high. With the guns used previously, the exposed needles clogged easily. “We looked at the situation on the ground with Fuchsberger, went through possible modifications in theory, and reviewed the most promising idea in a real-life setting,” says Sascha Zolldann, Area Sales Manager at Dürr, in describing the approach. The very first test in the dye shop showed that the automatic → EcoGun AS Auto Mini FS can reliably handle the short cycle without losing alignment or dripping thanks to its fast switching pulse. The result was confirmed after a station in the plant was equipped with a total of twelve Dürr spray guns.

Hen’s eggs have a very small surface area, but the demands involved in coating them are still high. “Colored eggs are presented to customers in butcher shops or bakeries on well-lit counters, and they form an opinion about the quality from the outer appearance. We’re very happy with the homogeneous color, level of shine, and color intensity we get with the EcoGun,” says Martin Wüst. The EcoGun AS Auto Mini has been specially developed to achieve as good a spray pattern on small areas as the big painting robots do on car bodies. Apart from plain colored eggs, the spray gun can also produce special effects like stripes in all the colors of the rainbow. With its flat round spray pattern, the spray gun applies with a high degree of precision. As a result, the color transitions look as sharp as if the egg had been stenciled. Something the Easter Bunny would need a delicate touch and even more patience for!