Why the painted stainless steel water cup with spray painting can pass the dishwasher test, but powder coating can’t?

Foreign trade-type water cup factories will meet customers' requirements that the sprayed stainless steel water cup must pass the dishwasher test, especially the factories that are mainly engaged in the European and American markets. As a company with nearly 20 years of experience in the production of water cups, we often encounter such requirements from customers. The surface of some customized water cups is spray-painted, and the surface of some customized water cups is powder coating. Regardless of the spraying process used on the surface of the water cup, there will be customers who require a dishwasher test. But why the painted stainless steel water cup with spray painting can pass the dishwasher test, but powder coating can’t?

After many years of customer requirements, it was found that painted stainless steel water cups are easier to pass the dishwasher test, while water cups with powder coating are difficult to pass. This problem has puzzled us for a long time, especially the customer insisted that purchasing other water cups with powder coating can pass the dishwasher test, which makes us even think it is our own problem, perhaps the problem of the material or the problem of the processing method.

For this reason, we did not hesitate to purchase the plastic powder that is said to have the best performance in the world and many plastic powders whose abbreviations can pass the dishwasher test. At the same time, the baking temperature after spraying was tested for multiple temperature values. After hundreds of tests, we found that some plastic powders do have a certain degree of improvement through baking at a suitable temperature, and no more than 10 cycles of testing were found to meet customer requirements. But once it was tested according to 60-120 cycles, none of the sprayed water cups passed the dishwasher test.

What is the reason why water cup with powder coating cannot pass the dishwasher test? After many times of analysis and discussion, and through the analysis of experts, we finally concluded that the failure of the plastic sprayed water cup to pass the dishwasher test has little to do with the plastic powder and baking temperature and time.

The main reason is that the plastic powder is granular, and the surface of the water cup will have an uneven matte feeling. Dishwashing liquid blocks are added when the dishwasher is washing. When cleaning, the dishwasher cannot clean the surface of the sprayed water cup, and there will be very little detergent residue.

At the same time, since the dishwasher needs to be cleaned at 70°C, the long-term temperature environment will cause the residual detergent to corrode the surface of the water cup. The longer the test, the more obvious the effect will be, and the surface of the spray water cup after taking it out will appear mottled like a white mist. The painted water cup is precisely because the dishwasher has no detergent residue during cleaning, so after many tests, the similar situation will not appear.

Dongguan Zhanyi Commodity Technology Co., Ltd. mainly produces various types of drinking utensils such as stainless steel water cups, plastic water cups and kettles. Our company has a complete automatic paint spraying and powder coating production line, which can be processed in customized colors according to customer requirements. As of December 2020, we have provided product innovation services to more than 200 customers around the world. Global buyers are welcome to visit our official website, and we will have professional customer service staff online to provide you with services.