Best Liners and Coatings to Prevent Rust Stains on Tea tins

Rusting tea tins can affect the flavor of the tea itself and is not conducive to storing tea. Whether it is from a humid storage environment or the natural oils in tea leaves, when moisture comes into contact with the exposed metal surface, it breaks down the protective layer of the tinplate, causing corrosion. Therefore, to prevent this, we use special linings and coatings on the inside and outside of tea tin cans to form a solid barrier that resists water and acidic tea compounds and prevents oxygen from entering. By incorporating the most effective linings, such as epoxy phenolic and polymer laminates, and exterior finishes, including polyester powders and acrylic lacquers, the synergy between the two can create custom tea cans that are rust-free, reliable, and beautiful in the long term.

Adding epoxy phenolic lining to tea tins

Epoxy phenolic resins have always been the benchmark in the anti-corrosion industry in tea tin can interior coatings. These two-component systems chemically cross-link under heat to form a dense, pinhole-free film that can firmly adhere to the tinplate. The cured epoxy phenolic layer, applied by spray or roller, has a thickness of 12 to 25 microns and offers excellent resistance to the natural acids found in black, green and herbal tea blends. It also withstands condensation caused by temperature fluctuations, ensuring that micro-cracks will not occur. Additionally, the epoxy phenolic lining complies with FDA Article 21 and EU Food Contact Regulation No. 10/2011, ensuring that no harmful compounds will migrate into the tea leaves. Including epoxy phenolic linings in a tea tin preserves the integrity of the container while maintaining the quality of the tea leaves.

Incorporating BPA-free polymer linings for health-conscious consumers

To make the lining of tea tins even more specific and safe, we can customize them with BPA-free polymer coatings. These water-based formulations cure at lower temperatures, eliminating concerns associated with BPA exposure. Despite the milder chemistry of these liners, they still offer excellent barrier properties, effectively blocking out moisture and tea oils. Polymer liners achieve uniform coverage of 15-30 microns via curtain coating or roll mill application. They also provide a smoother, more flexible inner surface that prevents cracking during can forming. This flexibility prevents delamination during deep drawing or forming; for tea producers who prioritize health and environmental stewardship, BPA-free polymer liners offer peace of mind without compromising corrosion resistance.

Polyester and acrylic outer coatings for durability

Inner linings prevent rust from the inside, while high-performance outer coatings protect tea tins from environmental moisture, mechanical abrasion, and UV exposure. Polyester powder coatings, applied at thicknesses of 50 to 80 microns and cured at temperatures of 180 to 200°C, form tough, chemical-resistant shells. Their cross-linked polymer network resists chipping, scratching, and fading, even in retail displays exposed to sunlight.

Acrylic liquid coatings cure under UV or ambient conditions. These coatings adhere well to the epoxy primer surface of custom tea tins, offering a range of gloss and matte finishes. By layering a polyester or acrylic topcoat over the primer, we achieve a modern aesthetic in tea tins that maintain their gloss and rust resistance through repeated use.

Advanced Barrier Films and Multi-Laminates

For the most demanding applications, such as high-acid tea blends or those requiring extended shelf life, we utilize multi-layer laminate liners inside tea tins. These barrier films are typically laminated from PET/aluminum foil/PET and then bonded to the inside of the tinplate. The aluminum foil layer completely blocks moisture and oxygen, while the outer PET layer provides chemical inertness and mechanical toughness. Film thicknesses range from 50 to 100 microns. This laminate liner does not require high-temperature curing, is suitable for temperature-sensitive teas, and can increase line speeds. With these advanced barrier films, tea caddies can achieve best-in-class rust resistance, ensuring that the tea leaves retain their delicate flavor.

Some tips for handling and storing tea tins

Even the best quality linings and coatings can suffer if not stored properly. To keep your tea tins rust-free, we recommend storing empty tins in a climate-controlled warehouse with an ideal temperature range of 10-25°C and a relative humidity of 40-60%. This environment helps prevent condensation. Additionally, during packaging, ensure that the filling line and sealing equipment are dry and free from steam or mist. After production, we ship in dry cartons with desiccant packs to absorb residual moisture. For consumers, it is recommended to refrigerate or store the tins in a calm, well-ventilated place to avoid humid conditions, such as those that occur after brewing. By combining powerful lining and coating technology with strict handling and storage methods, you can ensure that your tin cans remain intact and rust-free.

Linings and coatings for the best protection against rust

To protect your tea tins from rust, we use suitable liners, such as epoxy phenolic or BPA-free polymers, followed by advanced outer coatings (polyester and acrylic), and, where necessary, integrated multi-layer composite barrier layers. Through the combination of these several linings and coatings, along with stringent surface treatment and quality control, we can produce custom tea caddies that can withstand humidity, acidity and temperature fluctuations.