Presto New Logo

What are the Defects in Preforms Identified Under Natural Light?

The look and performance of items such as PET bottles can be influenced by mild strain or stress. PET materials are widely employed in a variety of sectors for a variety of purposes. PET is used in the manufacturing of chemical, medicinal, and food packaging and many other industries. Thus, testing the defects or strains present in PET products is essential to deliver quality products to the customers.

We at Presto have come up with Polariscope strain viewer computerized model. This testing instrument is commonly utilized in PET preform and glass structural testing. It operates on the basis of the optical principle, which takes into account the refraction of light rays.

Here in this blog, we will discuss the defects in preforms that will be identified under natural light. But before that, we will provide you with brief information about Polariscope strain viewer.

Easily identify the defects in PET products with Polariscope strain viewer

The PET bottle manufacturers make the use of blow moulding process to blow the preform structure. While performing this procedure, sometimes it may happen that stress is formed in these products. Thus, conducting quality tests is of utmost importance to make sure that you deliver quality products to your customers. With the help of Presto strain viewer for PET bottlesit will be easy for you to detect the strains present in products. This is one of the highly advanced testing instruments that will be used for stress analysis in products. This testing equipment detects even a little alteration in the material distribution along with a small change in the Preform refractive index. It makes use of dual intensity light source, monochromatic light source, and sodium lamp light source. This will help you to detect the flaws present in the products very clearly.

The Polariscope Strain Viewer is primarily used to detect preform flaws including water flash, air bubbles, strain distribution, crystallization, and so on. The manufacturer can simply measure the causes of problems on the Preform and eliminate the defects to avoid rejections with the aid of this testing machine. Under polarized light, the testing machine aids in the evaluation of the sample.

Features and Technical specifications of Polariscope strain viewer

If you're seeking the best testing equipment for determining product quality and transparency, a Polariscope strain viewer from Presto Testing Instruments is a good choice. It will assist you in performing the greatest quality assurance tests possible, ensuring that your consumers never have the opportunity to complain about your products. Because of the different strain distribution, any change in the refractive index of a product will occur. This will gradually reduce the material's transparency.

Below we have listed the features of this lab testing equipment computerized model:

  • Two light intensities were offered: Monochromatic light and Sodium Lamp.
  • Sharper and clearer optical viewing experience.
  • Standard Template for viewing sample at 45º and 90º angle.
  • Large Viewing glass area.
  • High-resolution camera to take pictures with integrated POLCOM software
  • Standard reference defect pictures preloaded in software for easy reference
  • Pick & Place feature to compare test preform image with a standard image.
  • Test Report includes Reason For Defect Along With Suggested Action.
  • Inbuilt hardware/software CD.
  • Easy Data Management. Users can create product identification, company, checked by details, etc.

Technical Specifications of Polariscope strain viewer computerized model

  • The instrument provides a viewing area of 260mm x 240mm.
  • The machine works on the power supply of 220V.
  • The dimension of the testing instrument is 335x360x500 mm.
  • Standard T template Measuring Angle 45º and 90º

With these features and technical specifications, it will be easy for you to identify the defects in preforms. Now, let us discuss different defects in preforms that can be identified in natural light.

Different types of defects detected under the natural light of Polariscope

Thermal Degradation: This is one of the common defects that can be detected under the natural light of this testing instrument. The possible cause of this defect is that preform temperature is too high or mould cooling is not uniform. 

  • You can easily overcome this defect by increasing the manifold temperature.
  • Excessive crystallinity insufficient mould cooling: Another common defect that can be seen under natural light is the excessive crystallinity insufficient mould cooling. This defect will happen due to the low temperature of tip/manifold, hold pressure/time will be too low, mould cooling time will be too high or decompression time will be too low. Thus, you can easily overcome this defect by increasing the manifold temperature and decreasing hold pressure and time. You can also decrease the mould cooling time if it is too high.
  • Preform tip crystallinity: This defect will occur in preforms when the temperature will be too low and hold/pressure time will be too high. Thus, you can easily overcome this defect by increasing the tip temperature and checking the mould cooling/core.
  • Side-wall - haze non-optimum drying: This type of defect will usually happen due to poor drier operation and poor mould cooling. To make sure you will deliver error-free products, you can overcome this defect by checking the drier operation and core cooling process.

These are some of the defects that can be experienced in natural light. You can easily check the deformity in the natural light with the help of a Polariscope strain viewer. To know about this lab testing equipment price, or want to conduct a FREE online demo, then give us a call at +91-9210 903 903 or email us at Our team of technical experts will easily assist you with all your queries.

Catalogue 2023

Our latest product catalogue cum company profile is now
available to download. Where should we send your FREE copy?

News letter Image