Deep Analysis of Formulas Stored in Cosmetic Tubes
Compatibility of Tube Material with Formula
Plastic Cosmetic tubes are usually made of PE (LDPE, MDPE, HDPE), laminated plastics, or multi-layer materials. Each material affects how the formula behaves over time:
LDPE (Low-Density Polyethylene):
- Flexible and squeezable, ideal for lotions, gels, and facial cleansers.
- Chemically resistant to mild acids and bases but may absorb fragrance oils over time.
- Best for formulas with moderate viscosity; very thin liquids may leak or oxidize faster.
HDPE (High-Density Polyethylene):
- Rigid and durable, resistant to most chemicals.
- Ideal for thicker creams and ointments.
- Low permeability prevents water loss from hydrating formulations.
Multi-Layer Laminated Tubes:
- Often combine PE with barrier layers like EVOH or aluminum foil.
- Excellent for formulas sensitive to light, oxygen, or moisture.
- Protects serums, sunscreens, and antioxidant-rich creams from degradation.
Key Point: Formula stability depends heavily on tube compatibility. Active ingredients like retinol, vitamin C, or niacinamide are highly sensitive to light and oxygen, making laminated or opaque tubes essential.
Impact of Tube Design on Formula Stability
The squeeze tube’s closure system—whether screw cap, flip-top, or airless—affects product exposure and lifespan:
- Standard Screw Cap or Flip-Top Tubes: a. Adequate for non-oxidizing formulas. b. May allow slight air exchange, which can accelerate degradation of sensitive actives.
- Airless Cosmetic Tubes: a. Perfect for highly active formulas. b. Minimize air exposure, prevent contamination, and extend shelf life. c. Essential for serums, anti-aging creams, and oxygen-sensitive skincare.
- Dual-Chamber Tube or Multi-Chamber Tubes: a. Allow two incompatible components to remain separate until use (e.g., vitamin C + hyaluronic acid). b. Increase product freshness and efficacy.
Formulation Types and Storage Considerations
Different cosmetic formulations have unique storage needs in cosmetic squeeze tubes:
a. Creams and Lotions
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Water-in-oil (W/O) creams: Less likely to leak through PE tubes, relatively stable.
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Oil-in-water (O/W) creams: Can sometimes interact with PE over long periods if surfactants are strong.
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Best Practice: Store in opaque tubes to protect against light and minor air exposure.
b. Serums and Actives
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Serums often contain vitamin C, peptides, or botanical extracts that are oxygen-sensitive.
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Recommended Packaging: Airless tubes or laminated tubes with minimal headspace.
c. Gels and Aloe-Based Formulas
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Hydrophilic gels are prone to microbial growth if exposed to air repeatedly.
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Solution: Use tubes with hygienic dispensing tips and preservatives compatible with PE.
d. Sunscreens
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UV-sensitive formulas require tubes with high barrier properties or opaque plastics.
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Tube material must be compatible with emulsifiers and chemical filters to prevent leaching.
Chemical Interactions and Migration
Even inert plastics like PE can interact with certain formulations over time:
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Fragrance Oils: Can penetrate and soften PE, altering texture.
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Surfactants or Solvents: Strong surfactants may weaken tube integrity in thin-walled designs.
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pH Sensitivity: Highly acidic (vitamin C) or alkaline (some exfoliating gels) formulas can accelerate plastic degradation if not properly layered.
Solution: Multi-layer laminates or barrier coatings prevent migration and maintain product stability.
Temperature and Storage Stability
Cosmetic tubes are also subject to environmental stress:
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Heat: High temperatures can increase pressure inside the tube and accelerate chemical reactions.
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Cold: Some formulas may separate or harden, especially in single-layer PE tubes.
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Light: Transparent tubes allow UV penetration, which can degrade sensitive actives.
Recommendation: Store tubes in controlled environments and select opaque or UV-resistant materials for light-sensitive formulas.
Hygiene and Preservation
Tubes provide a more hygienic option than jars because users rarely touch the product directly. However:
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Repeated Squeezing: Can introduce air and microorganisms if the formula is water-rich.
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Preservatives: Formulations should be compatible with the tube material and designed to remain stable over the shelf life.
Airless tubes or multi-chamber tubes minimize microbial contamination while preserving formula integrity.
Comparison Table of Tube Materials and Formula Compatibility
| Material | Ideal Formulas | Barrier Protection | Sustainability | Key Considerations |
|---|---|---|---|---|
| PE / HDPE tube | Lotions, creams, gels | Medium | Low | Affordable, flexible, widely used |
| Laminated PE tube | Serums, sunscreens, sensitive actives | High | Medium | Excellent for light/oxygen-sensitive formulas |
| PCR Plastics tube | Lotions, shampoos, body creams | Medium | High | Slightly opaque, must test sensitive actives |
| Aluminum tubes | Sunscreens, ointments, high-value actives | Very High | High | Requires lining for acidic formulas |
| Bioplastics (PLA, sugarcane) tube | Mild lotions, shower gels | Medium | High | Heat sensitive, limited solvent resistance |
| Kraft Paper Tubes | Masks, scrubs, powders | Medium-High (if laminated) | Very High | Inner liner needed, less flexible |
Key Insights for New Materials
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Sustainability is growing in importance: PCR plastics, bioplastics, and kraft paper align with eco-conscious consumer trends.
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Barrier protection matters: Aluminum remains the top choice for highly sensitive, light/oxygen-prone formulas.
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Material-formula compatibility must be tested: Bioplastics and kraft tubes may require additional liners for water- or oil-based products.
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Design flexibility: Plastic and PCR plastics allow squeezable tubes, while aluminum and kraft tubes may need specialized dispensing mechanisms.
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Marketing value: Using eco-friendly materials adds brand storytelling opportunities for “clean beauty” and “green” campaigns.
