Purpose And Standard Operating Procedure Of Cobb Sizing Tester

It is vital for paper & packaging manufacturer to understand the purpose and standard operating procedure of Cobb sizing tester for quality assessment of paper or corrugated fibreboards. 

 

Purpose of Cobb Sizing Test

Cobb sizing tester determines the amount of water or any liquid absorbed by the paper, corrugated fibreboard, and paperboard in a given period of time under some conditions. Water absorptiveness is a function of various characteristics of paper or board such as porosity, sizing, etc. The high Cobb value of the papers and cardboards indicates the ability of the materials to retain or absorb the moisture. Depending upon the application of the board, the Cobb value needs to be maintained. The test includes examining of the quantity of water absorbed in a particular period of time by non-bibulous paper having a thickness of 0.1 mm.

Standard Operating Procedure for Cobb Sizing Tester

Presto Stantest manufactures the best quality of Cobb Sizing Tester as per the standard methods – TAPPI – T 441 and ISO – 1060 (Part 1) – 1966. The standard operating procedure of Presto’s Cobb Sizing Tester as per the mentioned standards is:

1. A sample of paperboard or corrugated box more than the edges of the fixture is taken. Now weigh it to nearest 0.1 gram.
2. Now place a cork sheet on the metal plate and then place the weighed specimen on it and clamp the specimen firmly to prevent any kind of leakage between the sample and the ring.
3. To ensure the leak-free clamping between the ring and the upper surface of the sample during the test, use soft elastic and non-absorbent gasket of same internal dimension as of the ring.
4. Now pour water into the fixture as per the requirement of the sample (reference 10mm marking & 25mm. marking) for 100ml & 250ml respectively and start your stopwatch immediately.
5. Let the sample inside the cylindrical ring for 120 seconds (in case of Paper) and 300 seconds (in case of corrugated boards)
6. Reject the samples that show any sign of spillage or leakage.
7. If any liquid is passed through the sheet to the rubber mat, the test is not acceptable and will be rejected.
8. The standards time period of 120 seconds on a single sheet using 10 mL of water to wet is 1 cm deep. (Time of the test can also be adjusted as per the nature of the paper).
9. Once the buzzer of the stopwatch buzz, take out the sample from the cylinder.
10. Now with the help of hand roller drain out the excess water from the sample without exerting any pressure and rotating the roller one time forward and one-time backward direction.
11. On corrugated boards, the roller is applied in the direction parallel to flutes of the corrugated board.
12. Now again weigh the sample.

Technical Specifications of Cobb Sizing Tester

The technical specifications of a Cobb Sizing Tester help manufacturers understand the machine’s testing capability, accuracy, and compliance with international standards. Below are the common technical specifications of a standard Cobb Sizing Tester used in the paper and packaging industry.

Parameter	Specification
Product Name	Cobb Sizing Tester
Application	Paper, Paperboard & Corrugated Board Testing
Test Standard	TAPPI T441, ISO 535
Test Area	100 cm²
Water Capacity	100 ml / 250 ml
Test Cylinder Material	Stainless Steel
Specimen Clamping	Manual Clamping Arrangement
Test Time	Adjustable as per standards
Timer Facility	Digital Stopwatch / Timer
Rubber Roller Weight	Approx. 10 kg
Roller Width	Approx. 200 mm
Accuracy	High Precision Testing
Body Material	Mild Steel with Powder Coating
Display Type	Digital / Manual (Model Dependent)
Usage Industry	Paper, Packaging, Printing & Corrugated Box Industry

Formula to Calculate COBB value

Cobb Value = Weight of the sample after testing – Weight of the sample before testing

It is very easy to operate Presto’s Cobb Sizing by following above mentioned, operating procedure.

If you are looking for Cobb Sizing Tester Price price then you can consult with us. We are considered to be the leading Cobb Sizing Tester Manufacturers that will provide you with high quality testing instruments to ensure zero rejections rates from your customers. To know more information about its features, price, and technical specifications, give us a call at +91 9210903903 or email us at info@prestogroup.com.

Frequently Asked Questions

Q1) What is Cobb value in paper testing?
Ans: Cobb value indicates the amount of water absorbed by paper or board material in a specified time.

Q2) Why is Cobb testing important?
Ans: It helps determine moisture resistance and quality of packaging materials.

Q3) Which standards are used for Cobb testing?
Ans: TAPPI T441 and ISO standards are commonly used.

Q4) What is the ideal Cobb value?
Ans: The ideal Cobb value depends on the application and type of paper material.