Plastic films can be seen everywhere in our life, such as fresh-keeping films and document bags in supermarkets, or greenhouse films and agricultural films in farms. There are also many kinds of commonly used plastic films. Among them, low density polyethylene (LDPE) film is widely used in agricultural film covering, industrial and commodity packaging because of its soft texture, non-toxic under long-term use below 80 degrees, convenient processing and good chemical stability.

Due to the high requirements for film transparency in the field of production and application, we generally use haze and transmittance to characterize its optical properties. There are many factors affecting the determination of haze and transmittance, including sample preparation, sample surface state and so on. Today, the color spectrum colorimeter mainly focuses on the influence of the sample surface state on the detection of light transmittance and haze of LDPE film. The main three points are as follows:
① Scratch on sample surface
First measure the haze value and transmittance value of a certain sample with cs-700, then treat the surface of the sample, repeatedly measure the haze and transmittance, and investigate the influence of surface scratch on the front transmittance and haze.
It is found that abrasion has a great influence on haze and a relatively small influence on transmittance. Therefore, the scratch should be avoided in both film production and film sample testing.

Contaminated by dust

② The sample surface is contaminated
The same thickness sample shall be measured. The surface pollution has a great influence on the haze value of the sample and a little influence on the transmittance. Both surface scratch and pollution increase the haze value. For light transmittance, it usually decreases, but some plastics such as PC and PS increase slightly due to slight scratch and polluted surface. This is because part of the incident light irradiated on the sample is reflected, slightly scratched and polluted, which reduces the reflection and increases the transmission. If the scratch and pollution are further aggravated, the light transmittance will decrease.

③ Difference of sample thickness
For the same kind of products, samples with different thicknesses are used, and the Haze Meter cs-700 is used to measure their light transmittance and haze. With the increase of sample thickness, the light transmittance shows a downward trend, but the haze increases. Why? Because the thickness increases, the more light is absorbed, so the light passing through the sample becomes less, and the light transmittance decreases accordingly. At the same time, The increase of thickness increases the light scattering, resulting in the increase of haze. It can be seen that it is meaningful to compare the transmittance and haze of the sample only at the same thickness.

To sum up, the above three points are not only the key to the detection of film haze and light transmittance, but also need to be paid attention to during transportation after the quality of the product is passed. It is worth mentioning that in fact, each kind of transparent plastic has its specific spectral selectivity, and the determination results are different with different light sources. However, the color spectrum Hazemeter cs-700 can easily solve this problem because it can provide cie-a, cie-c, cie-d65 and other measurement light sources. At the same time, it follows ASTM and ISO standards to meet the needs of customers for different test light sources and escort the detection of haze and transmittance!