A Comprehensive Guide to Aluminum Bottle Surface Treatment: Polishing, Painting, and Printing

Aluminum Bottle Surface Treatment

4.2.1 Semi-automatic Line Aluminum Bottles

The surface treatment of semi-automatic line aluminum bottles includes polishing, painting, and printing.

Polishing: We generally do fine polishing, which means polishing three or more times.

Painting: Divided into solid color and transparent; glossy finishing and matte finishing.

Solid color means that the base color cannot be seen; transparent color means that the base color can be seen, that is, the metal luster of the aluminum bottle.

Glossy means that it will reflect light obviously, while matte has poor reflection ability. Please see the following comparison photo:

Printing: Includes three printing methods: screen printing, heat transferred printing, and gas dyeing printing.

1. Screen printing: During printing, the ink is transferred from the mesh holes of the graphic part to the substrate through the extrusion of the scraper, forming the same graphic as the original manuscript.

Advantages of screen printing:

The screen printing equipment is simple and easy to operate. The printing and plate making are simple and inexpensive, and the adaptability is strong. Suitable for printing LOGO with simple design of 1-3 colors.

Disadvantages of screen printing:

• The amount of ink cannot be controlled: the printing color and thickness will change with the amount of ink output;

• Overprinting, cannot print gradient color patterns: screen printing can only print one color at a time, and cannot overprint complex patterns;

• Arc limitation: Screen printing, this process can only be used for relatively flat products. If it is uneven, screen printing cannot be used.

2. Heat transferred printing: This printing method is divided into two parts: transfer film printing and transfer processing. Transfer film printing uses halftone printing (with a resolution of 300dpi) to pre-print the pattern on the surface of the film, and then the printing on the film is transferred to the bottle through heating.

• Heat transfer printing versioning: Suitable for printing multiple styles with the same color and similar printing content. The versioning requires that the number of the two styles that need to be spliced ​​together is consistent, otherwise additional film waste will be generated.

Advantages of Heat transferred printing:

• The pattern is formed at once, no need for overprinting, and the pattern has strong adhesion.
• The printing effect is exquisite. 1-8 color printing drafts can be printed, and gradient color, shadow and other effects can be made.

Disadvantages of heat transferred printing:

• The plate making cost is high, and there will be film waste;

• Once the plate making is started, nothing can be changed, otherwise, it will need to be remade;

• It can only be printed on the straight body part of the bottle, and the shoulder (curved surface) and bottom of the bottle cannot be printed. For transparent colors: Since the process is to spray paint first and then print, the color of the primer will affect the color of the printing, thus causing a certain color difference.

3. Gas dyeing printing: The patterned flower paper is tightly wrapped on the surface of the product to be printed, and then baked at a high temperature of about 400℃-630℃ with the waste gas of gas combustion. The paper part is quickly carbonized, and the dye part is quickly vaporized and transferred and condensed on the surface of the processed product, and the dye can be diffused and penetrated into the inner layer of the product to be printed and dyed to form a firm printing effect.

Advantages: Can be printed on the shoulder (curved part) and bottom of the bottle.

Disadvantages:

The printing cost and plate making cost are high;

The flower paper is wrapped manually, the production capacity is low and the speed is slow;

The LOGO on the shoulder of the aluminum bottle cannot be too regular, otherwise the manual folding may cause misalignment and other problems.

4.2.2 (Fully) Automatic Line Aluminum Bottles

The surface treatment of fully automatic line aluminum bottles includes polishing and offset printing.

Polishing: Mainly for rough polishing, with obvious streaks.

Offset printing: It is a type of flatbed printing that can print 1-9 colors. In simple terms, gravure printing is a printing method that uses a rubber sheet (rubber cloth) to transfer the pattern on the printing plate to the substrate. It is named after the existence of the rubber sheet.

Advantages Analysis:

1. Short plate making time: a few hours. Usually, gravure printing machines are divided into 6-color and 9-color gravure printing machines. The gravure printing cost is usually included in the unit price and is not quoted separately.
2. High image quality: It is clearer and sharper than letterpress printing because the rubber sheet can be well in contact with the texture of the surface of the printing material.

Disadvantages Analysis:

1. If the customer's design draft contains image formats/gradient colors, there will be sawtooth phenomenon when gravure printing on aluminum bottles.
   
2. The number of colors that can be printed is affected by the gravure printing machine (some are 6-color gravure printing machines, which can only print 6 colors at most; while 9-color gravure printing machines can print up to 9 colors).
   
3. When printing on the shoulder, the pattern will be deformed because the shoulder will be slightly deformed after the automatic line is printed and the neck is reduced.

Conclusion

The choice of surface treatment for aluminum bottles depends on various factors such as the desired appearance, budget, and printing requirements. Semi-automatic line aluminum bottles offer more flexibility in terms of printing options, while fully automatic line aluminum bottles are more efficient for high-volume production.