Aluminum is not inert. Put an aggressive aqueous formula in direct contact with bare metal and over time you can get corrosion, discoloration, hydrogen generation and metal pickup in the product. An internal coating is the layer that keeps the liquid off the metal, and it is one of the least visible and most consequential decisions in an aluminum bottle.
What our published products currently carry
The catalog records the coating for each format, and the options differ by use:
- The AB330-S 330 mL beverage bottle is listed with a food-grade lacquer on aluminium 3004.
- The AB400-R, AB500-R and AB750-S are listed with an epoxy-phenolic internal coating on aluminium 99.5.
- The MC1000-W wide-neck canister is listed as natural finish on aluminium 5754 — appropriate for dry or low-reactivity contents such as powders and tablets, not a general-purpose choice for liquids.
Those are the coatings we hold as standard. If your formula needs something else, that becomes a tooling and qualification conversation rather than a dropdown selection.
When you can go without a coating
Dry goods are the easy case. If the package never sees water, the corrosion pathway is largely absent, which is why an uncoated canister is a reasonable starting point for powders and tablets. Low-water, non-conductive products such as anhydrous solvents or oil-based formulations are also far gentler on the metal than aqueous ones.
The moment water and ions are in the formula, treat the coating as required until testing says otherwise. Conductivity is a useful proxy: a formula that conducts electricity has ions in it, and ions are what carry the electrochemical reaction.
When a coating is not enough on its own
A coating is a continuous film, and continuous films have weak points. Three that come up repeatedly in review:
The neck and the thread area. Forming leaves the finish region hard to cover uniformly, which is why a coated body and an uncoated neck can behave very differently over shelf life.
Scratches and handling damage. Decoration happens on the outside, but filling-line handling, caps threading on, and secondary packaging pressure all happen on the inside.
The liner and the closure. The SC24-01 aluminum screw cap is listed with an EPE liner. The seal assembly is part of the contact system; a coated bottle with the wrong liner can still underperform.
How to actually specify one
Do not start from the coating name. Start from the formula and the claim you have to support:
- State the pH, whether it is aqueous, and the conductivity if you know it.
- State the fill temperature — hot filling is a very different coating stress than cold filling.
- State the shelf life you need and the storage temperature range.
- Ask for the coating to be evaluated against those four inputs, and keep the report.
Compatibility and migration requirements vary by market, and the applicable rules depend on where the filled package will be sold. We do not publish a compliance status for a coating until it has been confirmed for the stated use, so treat any coating listed here as a starting specification and the sampling review as the point where it gets signed off.
Bring the formula and target market to the customization discussion or request a quote and the coating review starts from your inputs rather than from a guess.