Semi-automatic Cobb Water & Oil Absorption Tester (ACT) - OpTest

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Semi-automatic Cobb Water & Oil Absorption Tester (ACT)

The Cobb semi-automatic instrument is used to determine the liquid permeability of paper and board which is very important in packaging papers, although this test is used in many types of papers. The instrument includes a cylinder, roller, and the stopwatch in a compact solution. This Unger based system can be used with water and oils. It has the advantage of making the testing process easier and more accurate. The built-in stopwatch starts at the beginning of the test and notifies the operator 15 seconds before the end. Ideal equipment for laboratories where many tests are carried out continuously.

Product Name Semi-automatic Cobb Water & Oil Absorption Tester (ACT)
Product Code PTA-090119
Standards/Methods TAPPI T 441, ISO 535, EN 20535, BS EN 20535, DIN 53 132, SCAN P12
Test Material Paper
Manufacturer The PTA Group / IDM (PTA)
Availability from OpTest Exclusive to Canada

• Unger type Cobb equipment
• Sample test area 100 cm2
• Valid for water and oil
• Timer with automatic start and pre-notice and end of test alarms (batteries included)
• The cylinder vessel can be turned over for a better immersion of the sample
• Manufactured under standard specifications
• Integrated pressure rolls with a mass of 10 ± 0.5 kg, standard specification
• Glass made vessel bottom for a better observation of the liquid absorption
• Robust construction in stainless steel
• Cutting template and pad to facilitate the samples preparation (included in standard supply)
• CE mark
• Weight (equipment only / with packaging): 20 kg / 30 kg
• Dimensions (W x L x H - equipment only / with packaging): 430 x 380 x 270 mm / 580 x 450 x 380 mm


The Cobb equipment allows to measure the liquid amount that penetrates in a paper sheet. It is the calculus of the weight of the absorbed liquid in a specified time per 1 m2 of paper. Pour 100 ml of liquid in the cylinder vessel. Weight the dry sample (adjusting to the nearest milligram) and place it, with the face to be tested, in contact with the perimeter of the vessel. Turn the vessel 180º by means of the lever. The timer will activate automatically. The liquid contained inner the cylinder will be now in contact with the sample. When the sound alarm is active, means that the programmed time for pre-notice has expired. Return the vessel to its initial position. Open the vessel cover, remove the tested wet sample and place it, with its wet face upwards, on a bottling paper. This bottling paper must be previously positioned on the movable support-basis Once expired the determined time since the beginning of the test (see times according to applied standard), place a second bottling paper over the sample. Eliminate the exceed of liquid from the sample by passing the 10 Kg roller twice (one time forward and another time backward) over it. Be careful not to apply an additional pressure to the roller when passing over the sample. Afterward, fold the sample, with the wet side to the interior part, and weight it again. Therefore, it will be possible to calculate, in grams per meter square, the increment in mass that has suffered the sample due to the liquid absorption. Besides of the Cobb equipment, to carry out a complete Cobb test, it is necessary to have blotting papers from 200 a 250g/m2 and an analytic scale with an accuracy of 0,001 g.


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