Barium Activity Number in Textile

Last Updated on 14/03/2022

What is Barium Activity Number?
The ability of mercerized cotton fiber to absorb more iodine, dyes, moisture and alkalis, and to undergo oxidation or hydrolysis at increased rates compared to unmercerized cotton, has been used to develop various methods of determining the degree of mercerization. The most successful method consists of measuring preferential absorption of barium hydroxide from its dilute solution by mercerized cotton. The extent of this absorption is more than that by unmercerized cotton under the same conditions. Thus ratio multiplied by 100, is known as barium activity number (BAN), barium number or baryta number.

mercerized and nonmercherized cotton

In the other way, Mercerized sample absorbs barium hydroxide (alkali) to a greater degree than sodium hydroxide and from practical point of view, barium hydroxide is more easy to estimate. The ratio of uptake for this reagent has been referred to barium activity number.

Barium activity number was measured by AATCC test method 89-1998. One gram of mercerized and unmercerized cotton yarns were each cut into small pieces, dried over phosphorous pentoxide for 5 hours, then conditioned at 65% relative humidity at 31̊C before testing and consequently treated with 30 ml of 0.25 N barium hydroxide solution in 100 ml conical flasks. After 2 hr, 10 ml of the solution is titrated against 0.1 N hydrochloric acid. A blank is also run without any yarn sample. For b, s and u being the titration readings of the blank, mercerized and unmercerized samples, respectively, the BAN may be given as in following equation.

Barium activity number (BAN) = {(b-s)/(b-u)} × 100


b = ml required for blank test,
s = ml required for mercerized cotton,
u = ml required for unmercerized cotton.

Appropriately large numbers of conditioned samples are taken, taking into consideration the moisture regain of the samples. Thus, if the moisture regains 8%, 1.08g of the conditioned cotton is weighted to get 1g of the bone dry cotton. The barium activity number of good mercerized cotton may be around 150-160.

The fabric’s barium activity number has an interesting correlation with many factors, such as the degree of crystallinity, the strength and the dyeability of the fabric, and it can be determined from its crystallinity index (measured from X-ray diffraction pattern in the fiber), strength and color strength. When the fabric’s barium activity number was under 150 or the mercerizing reaction was incomplete, the fabric’s crystallinity index was around 0.6–0.8. Once the reaction between the mercerizing agent and the fiber occurred completely as the fabric’s barium activity number was over 150, its crystallinity index decreased to 0.5 and lower. This could mean that a complete mercerizing reaction first occurred when the crystalline region located in the fiber was decreased to 50%.

The degree of mercerization of cotton fabric was measured successfully using an online near-IR spectroscopy method. The measurements were performed on a commercial Benninger Dimensa Mercerization Range, where near-IR Ml values correlated strongly with BAN values of the samples that were subsequently analyzed in the laboratory. The effect of the fabric temperature on Ml values was significant; however, either by software modification or using a direct light spectrophotometer technology, the sample temperature effect can be compensated.


  1. Principles of Textile Finishing by Asim Kumar Roy Choudhury
  2. Chemical Technology in the Pre-Treatment Processes of Textiles by S. R. Karmakar

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