How to Determine Carpet Thickness by Shirley Thickness Tester

Last Updated on 06/04/2021

Name of the Experiment:
How to determine carpet thickness testing by Shirley thickness tester.

Carpet is a floor-covering textile having surface formed from yarns or fibers projecting from a substrate. Fabric thickness is a parameter of fabric which involves handle, creasing, wrinkle resistance, thermal resistance and other fabric properties. A carpet is compressible and therefore it is necessary to specify at what pressure its thickness is to be measured.


  1. To determine the thickness of carpet and understand its related facts.

Anderson and Clegg state: Thickness as estimated by eye is similar to that measured by an instrument at low pressure, and by measuring thickness at increasing and decreasing pressures in the range exerted by a human foot, pressures of the order of 0-12 lb/in2 normally being encountered, we can obtain a measure of the behavior of carpets to imposed loads. Essentially the determination of fabric thickness consists of the precise measurement of the distance between two plain parallel plates when they are separated by the cloth, a known arbitrary pressure between the plates being applied and maintained. It is convenient to regard one of the two plates as the pressure foot and the other as anvil. The Shirley thickness tester has such two parallel plates. The upper plate serves as a collar and supports for the additional load which produce pressure. The dial gauge is graduated in mm which indicates the thickness of the carpet.

carpet thickness testing
Fig: Carpet thickness testing


  1. Shirley thickness tester
  2. Carpet
  3. Knife
  4. Scale.

Machine specification:

  • Name: Shirley thickness tester
  • Manufacturer: Shirley Developments Limited, Manchester.


  • Testing atmosphere: Relative humidity – 65%±2% & Temperature – 270±20C.
  • Present atmosphere: Relative humidity – 68% & Temperature – 290C.

Working Principle of Shirley Carpet Thickness Tester:

  1. At first we will take our sample carpet and cuts it with a knife.
  2. Place the carpet on the lower plate and bring down the upper plate on it.
  3. Load the dead weight on the collar and takes the reading from the dial gauge.
  4. Now add the other additional weights one after another on the collar to increase the weight.
  5. And take the readings from the dial gauge.
  6. After taking the last reading we will wait for 5 mins for the action of the weights on the carpet.
  7. Then we will again unload the weights from the collar one by one and take the reading of the thickness.
  8. From the beginning thickness and the last thickness of the carpet after compression we will find out the compression of the carpet and the recovery percentage.


S/nAdding load (gm)Total load (gm)Thickness (mm) after loadingThickness (mm) after unloading
190 (dead wt.)9012.812.5


Compression = (12.8 – 12.5) mm = 0.3 mm

………………..12.8 – 12.5
Recovery = ——————– x 100%

= 2.4%

Compression of the carpet = 0.3 mm and recovery = 2.4%.

Graphical Representation:
We can make a chart of loading and unloading on carpet thickness by placing the values of load or unload in Y axis and thickness in X axis. It is shown below:

Graphical Representation of carpet thickness test

The thickness of the carpet is compressed very little and so it may say that its load bearing capacity is good and its durability will be long. Again its recovery percentage is poor which indicates that if it is bended once it will not serves long which indicates that its service ability is poor.

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