Base coating is a common process for making aluminum collapsible tubes.


As packaging material, aluminum collapsible tubes are expected to be not only functional but also decorative. Almost all tubes used for consumer products are printed with logos, texts and graphics. However, it is less known that the underlying layer on the tube surface, usually in white, is applied onto the tubes through a separate process called base coating. Why?


The materials used for printing and for base coating are actually different. The former uses ink, and the later applies resin (and pigments if the coating is colored). Polyester resin, an ideal coating material, provides significant protection to the tubes. It has great flexibility and adheres well to aluminum. When forming an excellent film on the tube, it is resistant to scratch and can protect tubes from corrosion.


The most common coated tubes are the ones with a layer of white resin completely covering the surface of the tube. However, coatings in different colors are getting more and more popular for the sake of product design. Therefore, it is fair to say that base coating has both protective and decorative purposes.


How is base coating applied? Extruded aluminum tubes will be put on the scrolls in the base coating machine after having gone through trimming, annealing and internal lacquering. Through the rolling of the scrolls, polyester resin is to be coated evenly onto the surface of the tubes to form a coating.


Coated tubes must be sent for baking, heating the coating to fuse the fine particles of the resin. The temperature on the metal tube surface is kept between 150 and 160 degree Celsius for 5 to 6 minutes. A coating of a metal-adhesive resin layer is then formed. After that, tubes will go through the offset printing process to have texts and images printed.


Base coating is an important procedure to make high quality packaging tubes. The raw materials used for base coating should conform to relevant regulations, such as ones from FDA. Finely applied base coating ensures the quality of printing conducted later on.


If you look closely at the empty aluminum collapsible tubes, you might notice that the inner wall of some tubes is lined with a band near the open end. This is called “latex lining”, one of the essential techniques that contribute to tightness of tube packaging.


Chemicals such as adhesive glue and cosmetic cream have differing technical features. Some dry fast and should be kept strictly airtight. Some react easily to moisture or air. Still others are somewhat corrosive and should be filled and stored in specially prepared containers. In all of these cases, extra tightness of tube packaging is required to ensure the shelf life of products.


To achieve extra tightness, a band made of latex is applied to the inner wall of aluminum tube near the open end. The soft latex would fill tiny slits when the open end of tube is crimped and folded. It helps sealing more effectively.  It prevents content leakage and also prevents moisture and contaminants from penetrating into the tube.


Latex lined tubes are commonly adopted to package a variety of products, including silicone sealant, rubber cement, epoxy adhesive, cosmetic cream, and hair colorant. The width of latex band can and should be adjusted to maximize the airtight effect of tube.


Please contact Xin Yi if you are not sure whether your tube requires latex lining to achieve optimal tightness.




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