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Tinplate Deodorant Spray Cans: Aluminum Salt Formula Triggers Inner Coating Blistering and Peeling, Causing Deterioration and Discoloration of Deodorant Sprays
2026-06-11
After deodorant sprays are launched on the market, numerous consumer complaints keep coming, including turbid and discolored liquid, strange metallic odors and even can leakage. After tracing the root causes, damaged inner coatings of tinplate deodorant spray cans become the main problem. Aluminum salts widely used in product formulas greatly accelerate coating failure and product deterioration, which has troubled many daily chemical manufacturers for a long time.
1. Aluminum Salts: Hidden Corrosion Risks in Aerosol Can Internal Coating Anti-Aluminum Salt Corrosion
1.1 Physical and Chemical Properties of Aluminum Salt Ingredients in Deodorant Sprays
Aluminum chlorohydrate is a core functional material for deodorant and antiperspirant sprays, which has been widely used in the daily chemical industry for years. Its aqueous solution has a pH value of about 4.5 with mild corrosivity. It works by forming aluminum ion deposits on sweat glands to inhibit sweat and remove odor. Most formula developers focus on product efficacy and user experience, while ignoring the continuous chemical reaction when the material contacts tin-coated tinplate Aerosol Cans for a long time.
When aluminum salt molecules touch the inner wall of cans, continuous hydrolysis will occur and produce acidic substances. These acidic media constantly erode the tin plating layer and break the balance between coatings and metal substrates, kicking off various coating failures.
1.2 Complete Evolution from Coating Damage to Product Deterioration
Minor coating damage will gradually evolve into large-scale quality issues. The whole failure process follows a clear sequence:
- Acidic media slowly penetrate the interface between coatings and metal substrates and weaken the original adhesion of coatings.
- Water vapor and soluble salts accumulate in interface gaps, forming tiny invisible blisters on the coating surface.
- Blisters expand and connect with each other, eventually leading to coating warping and partial peeling.
- The tin plating layer and metal substrate are directly exposed to spray liquid, resulting in continuous precipitation of iron ions and tin ions.
- Metal ions mix into the liquid, causing discoloration and metallic odor. Severe corrosion will further lead to perforation and leakage of cans.
Can standard coatings completely avoid such problems? In fact, ordinary coatings can hardly resist the dual impact of aluminum salt formulas and high temperature & high humidity storage, which explains why most quality failures break out intensively after months of warehousing.
2. Two Main Blistering Mechanisms for Deodorant Spray Can Coating Protection
Epoxy phenolic coating is the most commonly used inner coating material for tinplate deodorant Spray Cans. It delivers reliable adhesion and resistance to common acids and alkalis, but blistering still occurs when exposed to aluminum salt formulas, mainly caused by two mechanisms.
2.1 Osmotic Blistering: Physical Damage Caused by Accumulated Salts
During filling and sealing, a small amount of soluble salts such as chlorides and sulfates in formulas will remain in the gaps between coatings and metal surfaces. In long-term storage, obvious osmotic pressure difference forms inside and outside the gaps. Water vapor penetrates the coating and accumulates at the interface, eventually forming blisters of different sizes. Welds, curled edges and other connecting parts of cans have more gaps where salts tend to stay, so these areas are high-risk zones for blistering.
2.2 Wet Adhesion Failure: Chemical Reaction Destroys Coating Bonding Force
Massive hydrogen ions produced by aluminum salt hydrolysis keep lowering the pH value at the coating-metal interface and break the coordination bonds between coating resin and metal oxide layers. The originally firm coating structure gradually loosens and peels off partially. Many practitioners have noticed that cans filled with aluminum salt deodorant sprays have a much higher failure rate than those filled with common water-based products, and the root cause lies in this chemical adhesion loss.
Temperature difference during long-distance transportation and high humidity in warehouses will further speed up chemical reactions and advance coating failures.
3. Aerosol Can Coating Adhesion Test and Standard Corrosion Resistance Tests
A complete set of quantitative testing systems has been formed in the industry to evaluate the overall protection performance of coatings and predict the compatibility between cans and aluminum salt formulas in advance. Details of major tests are listed below:
| Test Item | Testing Purpose | Reference Standard | General Qualification Requirement |
|---|---|---|---|
| Tape Pull Adhesion Test | Check dry and wet adhesion strength of coatings | ASTM D3359 | No large-area coating peeling, adhesion reaches Grade B or above |
| Neutral Salt Spray Test | Evaluate overall anti-corrosion performance of coatings | Industrial General Standard | No blistering or obvious rust after 480 consecutive hours of testing |
| Scratch Expansion Corrosion Test | Assess anti-corrosion expansion ability after coating damage | Special Standard for Aerosol Cans | Corrosion expansion width within limited range |
| Formula Immersion Aging Test | Simulate real working conditions after long-term filling | Custom Aging Scheme | No coating blistering or peeling after 6/12/24 months immersion |
| Electrochemical Impedance Monitoring | Track metal corrosion progress under coatings in real time | Material Corrosion Standard | No sharp decline of impedance and no pitting signal |
These tests help eliminate unqualified cans before mass production and reduce product deterioration risks fundamentally. Scanning electron microscope can also observe the cross-section of coatings to check hidden defects such as gaps and delamination at the interface.
4. Performance Comparison of Three Mainstream Inner Coatings
Different inner coating resins show distinct performance in anti-aluminum salt corrosion, moisture and heat resistance and process adaptability. Combined with the actual application of tinplate deodorant spray cans, the comparison is as follows:
| Coating Type | Acid Resistance | Long-term Adhesion Retention | Blister Resistance | Moisture & Heat Resistance | Applicable Formula pH Range |
|---|---|---|---|---|---|
| Epoxy Phenolic | Good | Gradual attenuation | Average | Excellent | 5.0~9.0 |
| Organosol | Fair | Stable | Good | Weak | 5.5~9.5 |
| Modified Epoxy | Outstanding | Almost no attenuation | Excellent | Good | 4.0~10.0 |
Epoxy phenolic coating is cost-effective and the first choice for general-purpose cans. Organosol has better flexibility and higher tolerance to chloride ions, suitable for scenarios with frequent can deformation. Zinc-reinforced modified epoxy features higher crosslink density and optimal protection against weak acid formulas containing aluminum salts, widely used for high-end deodorant spray products.
5. Practical Case: Quality Crisis Caused by Improper Coating Selection
SAILON is an experienced manufacturer focusing on customized tinplate deodorant spray cans, and we have dealt with numerous real cases from daily chemical manufacturers. One of our partners adopted standard epoxy phenolic coated cans for mass production of deodorant sprays. Half a year after product launch, the brand received a large number of customer complaints about discolored liquid and metallic odor.
Laboratory tests proved that the iron ion content in finished products exceeded the industrial limit, which was caused by gradual coating peeling after long-term contact with aluminum salt formulas. We designed a new double-layer composite coating structure with inner organosol and outer epoxy phenolic coating, and optimized the process for aerosol can internal coating anti-aluminum salt corrosion according to the formula, storage environment and transportation routes. After 24-month full-cycle aging test, no blistering or peeling occurred on coatings, and product quality remained stable completely.
6. Inspection Checklist for Procurement and Quality Control
Follow the points below to inspect suppliers and set cooperation standards, so as to avoid potential quality risks:
- Require suppliers to provide complete test reports of full-cycle immersion aging with target aluminum salt formulas
- Verify three core indicators: dry film thickness, surface pinhole quantity and dry & wet adhesion of coatings
- Obtain cross-section SEM images of aged coatings to check the bonding condition between coatings and metal
- Check metal ion test data of finished product leachate to ensure compliance with industrial safety standards
- Clarify the notification rules for coating material and painting process changes, and require full re-test after any adjustment
7. Frequently Asked Questions (FAQ)
- Will cans be corroded inevitably if formulas contain aluminum salts? Not exactly. Corrosion is determined by coating material, painting technology, film thickness and storage conditions. With targeted protective coatings, tinplate deodorant spray cans can keep stable even when filled with aluminum salt deodorant sprays for a long time.
- Which parts of tin-coated tinplate aerosol cans are most vulnerable to coating failures? Welds, curled edges and can necks have more gaps where salts and water vapor accumulate easily. These positions are high-risk areas for coating blistering and peeling, and need key attention during inspection.
- How to quickly confirm whether can coatings match existing deodorant formulas? Carry out short-term formula immersion test combined with salt spray test. Qualified results of the two tests prove good compatibility between cans and formulas.
- What is the ideal warehouse environment to slow down coating corrosion? Keep the warehouse well-ventilated and dry, and avoid long-term sealed environment with high temperature and humidity. Stable ambient conditions can greatly slow down the chemical reaction between aluminum salts, coatings and metal substrates.
8. Build Long-term Can Protection System from the Source
From various failure cases, we can see that aluminum salt formulas are not difficult to apply. Mismatched coating solutions are the real cause for failure of tinplate deodorant spray cans and product deterioration.
SAILON has been engaged in customized aerosol can production for years. We keep optimizing coating systems and production technologies for daily chemical products with aluminum salt formulas such as deodorants and antiperspirants. We provide one-to-one customized inner coating solutions based on clients’ formula pH, filling specification, storage & transportation conditions and expected service life. We eliminate risks of coating corrosion and product deterioration at the production stage, and help partners maintain stable product quality and market reputation.