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Test Method for Dry Weight of Grey Fabrics without Pulp

May. 13, 2020

In textile business negotiations and contract signing, there is often a requirement for the gram weight of grey fabrics. The gram weight of grey cloth refers to the dry weight of grey cloth per square meter, referred to as the dry weight of grey cloth. It is an important technical index of grey cloth and the main index for economic accounting of fabrics.

According to the size and specific conditions of the grey fabric sample, it can be divided into two test methods: weighing method and calculation method.

Grey Fabrics

The calculation method needs to know the weaving shrinkage ratio of warp and weft yarns.

Sometimes the deviation of the warp and weft yarn shrinkage ratios is large, resulting in a large error in the calculation results. 

In general, the laboratory and testing centre of the grey fabrics factory use a more accurate weighing method to test the dry weight of gray fabric without pulp.

Apparatus and tools required for measuring the dry weight of grey cloth by weighing method: balance (pallet balance or electronic balance), induction cooker (usually 1500W), copper pot (or beaker), measuring cup, glass rod, concentrated sulfuric acid, iodine Light preservation), oven, etc.

First, preparation of dilute sulfuric acid solution:

Dispose more than 95% of concentrated sulfuric acid into a certain concentration of dilute sulfuric acid (according to the proportion of 500ml of water added to 100ml of concentrated sulfuric acid): first inject a certain amount of water into the beaker, measure the appropriate amount of concentrated sulfuric acid in the measuring cup, take the measuring cup in the left hand and the right hand Take the glass rod and slowly pour the concentrated sulfuric acid into the beaker water while stirring. After cooling down, pour the configured dilute sulfuric acid into a small glass container and place it tightly.

Note: Since concentrated sulfuric acid will evaporate and splash during the stirring process, the operator should wear plastic gloves and masks.

Second, the test steps are as follows:

1. Sampling cloth:

use the disc sampler to take the sample of the grey cloth (area of 100 square centimetres) or use scissors to cut the sample cloth into a rectangle or square, use a ruler to measure the length and width of the sample cloth, and calculate the sample cloth Area (cm2)

2. Boil the sample fabric

(According to the proportion of 10 grams of gray cloth corresponding to a minimum of 700 ml of water) measure the water needed for the test sample cloth into the copper pot (or beaker), and then put it on the induction cooker to heat it. After the water boils, put the sample cloth to cook 10 minutes, use a glass to help remove the sample cloth and wash it with clean water.

3. Dilute sulfuric acid, desizing

(According to the proportion of 10 grams of gray cloth corresponding to a minimum of 700ml of water) Then use a measuring cup to measure the water required for the test sample cloth and add it to a copper pot (or beaker), put it on the induction cooker and heat it to boiling, (according to 700ml of water corresponding to 14ml of dilute Proportion of sulfuric acid) Measure the amount of dilute sulfuric acid in the measuring cup, add the sample cloth to boiling water, cover and cook for 40 minutes, use iodine solution to detect whether the sample cloth is desizing is clean, if not, continue to cook, Until the slurry is removed, remove the sample cloth with a glass rod and rinse it with clean water.

4. Sample drying

Open the oven, lay the sample cloth on the oven partition and bake for 1.5-2.0 hours, weigh the dried sample cloth with a balance, and calculate the dry weight of the sample cloth.

5. Calculate the weight

Due to fiber loss during desizing and cleaning, correct the loss factor to calculate the dry weight of grey fabric without pulp.

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