Publication date: 2025-05-19
HDPE and LDPE films are the most popular materials used in the production of plastic bags, packaging, and technical films. Although both belong to the polyethylene group, they differ significantly in appearance – especially in terms of transparency.
In this article, we explain:
- how HDPE and LDPE film transparency differs,
- why LDPE is also not perfectly transparent,
- what influences the optical properties of films,
- why this matters in practical applications.
What is film transparency and why is it important?
Film transparency is the ability of the material to transmit light in a way that allows the contents of the package to be seen. The higher the transparency, the more visible the product inside.
In industries such as:
- food (bread, vegetables, frozen goods),
- cosmetics,
- medical,
film transparency is one of the key parameters when choosing the right material.
HDPE vs LDPE – differences in transparency
| Parameter | HDPE (High Density Polyethylene) | LDPE (Low Density Polyethylene) |
| Material density | High (0.94–0.97 g/cm³) | Lower (0.91–0.93 g/cm³) |
| Crystallinity | High | Lower |
| Film appearance | Milky, matte | Transparent with slight haze |
| Light transmission | Low | Higher than HDPE, but not fully transparent |
Conclusions:
- HDPE will always be more matte and milky.
- LDPE is more transparent but will never achieve full clarity like PET or CPP film.
Why is LDPE never fully transparent?
Despite its lower density, LDPE has an amorphous-crystalline structure with branched polymer chains. This causes partial light scattering, resulting in the characteristic slight haze of LDPE films.
Thin LDPE films can be very transparent but will always have a subtle milky effect.
Factors affecting HDPE and LDPE film transparency:
- Film thickness – thinner films are more transparent.
- Processing conditions – temperature, cooling speed, calibration.
- Clarifying additives (masterbatch) – improve LDPE optical properties.
- Raw material quality (regranulate vs virgin) – lower quality regranulates can reduce transparency.
- Surface treatment (e.g., corona) – enhances visual effect but does not change material structure.
When to choose HDPE or LDPE?
✅ HDPE – where strength, stiffness, and cost matter.
✅ LDPE – where appearance, transparency, and flexibility are key.
FAQ – Frequently Asked Questions
Can LDPE film be fully transparent?
No. Due to its structure, LDPE can never be perfectly clear like glass. However, its transparency can be significantly improved with clarifying additives and optimized processing.
Why is HDPE film matte?
This is due to its high crystallinity and density. Light scatters on the crystalline phase boundaries, giving a milky, matte appearance.
Do films made from regranulate have worse transparency?
Yes, especially if the regranulate comes from low-quality waste or is poorly filtered. High-quality regranulates can achieve properties comparable to virgin material.
Summary
HDPE and LDPE differ not only mechanically but also visually.
LDPE has higher transparency but is never fully clear.
Choosing the right film depends on the application – transparency is just one of many parameters.
At Uniplast, we help select the right film for each customer's specific needs.
Learn more: www.uniplast-folia.pl/produkty
Request a quote: uniplast@uniplast-folia.pl
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