**Textile Dyeing Calculation Related Terms:**

Dyeing calculation is very important to dye the fabric perfectly. To calculate the **textile dyeing** calculation, some important terms are frequently used in the textile wet processing sector. Those terms have explained in this article.

**Different Terms Used in Wet Processing Calculation:**

There are some important terms used in textile dyeing calculation, those are explained in the following:

**1. Expression of mixtures:**

There are several ways involved to calculate the weights and volume of textiles and chemicals. The major relations are given in the below:

**a. Weight to weight (W/W):**

This expression indicates that one unit of weight is related to the weight of another substance.

**b. Weight to volume (W/V):**

This expression indicates the weight units of one substance to the volume units of another material.

**c. Volume to volume (V/V:**

This expression relates the volume of one substance to the volume of another substance.

**2. Molarity:**

When one mole or gram molecular weight of solute is dissolved in one liter of solution is known one-molar (1M) solution.

For example,

1M HCl contains 36.5 gm HCl per liter,

0.1M HCl contains (36.5×1= 36.5) gm HCl per liter,

**Again,**

1M H2SO4 contains 98 gm H2SO4 per liter,

0.01M H2SO4 contains (98×0.01=0.98) gm H2SO4 per liter,

**Again,**

1M NaOH contains 40 gm NaOH per liter,

0.001M NaOH contains (40×0.001=0.04) gm NaOH per liter.

**3. Normality:**

When one gram equivalent weight of solute is dissolved in one liter of solution is known as one-normal (1N) solution. It is calculated from the molecular weight divided by the hydrogen equivalent (maximum valence of ion) of the substance.

*You can follow the below examples-*

1N HCl contains 36.5 gm HCl per liter,

1N H2SO4 contains 98 gm H2SO4 per liter,

1N NaOH contains 40 gm NaOH per liter,

**Now,**

0.1N HCl contains (36.5×1= 36.5) gm HCl per liter,

0.01N H2SO4 contains (98×0.01=0.98) gm H2SO4 per liter,

0.001N NaOH contains (40×0.001=0.04) gm NaOH per liter.

**4. Specific gravity:**

The ratio of the weight of a defined volume (density) of a substance to the weight of an equal volume (density) of some reference substance is known as relative density or specific gravity.

For liquids or solids, it is the ratio of the density (usually at 20°C) of water (maximum density) measured at 4°C. Since the weight of 1cc water at 4C is 1gm the specific gravity of water is taken 1 at 4°C.

In a general sense, specific gravity indicates the weight of 1ml of substance.

For example, the specific gravity of sulfuric acid 1.84 means that 1ml of this sulfuric acid is 1.84gm.

**5. Determination of specific gravity:**

In the textile wet processing industry, specific gravity plays an important role to maintain process parameters. Usually, an instrument named hydrometer is used to determine the specific gravity of the solution. But it can also be calculated by using the below formula.

**Specific gravity (SG),**

= (Weight of liquid/ volume of the liquid)

Specific gravity can easily determine by putting the weight value in grams in the formula.

**6. PH of liquid:**

In practice, the PH of any liquid can be measured directly by using a PH meter. But is a big question, what does the pH mean? What is the meaning of PH-5 and PH-10?

Actually, PH is the relative amount of hydrogen ion in a solution. It is defined as; PH is the negative logarithm of hydrogen ion in a solution. It measures the moles of hydrogen ion per liter of solution.

*It should be noted here that,*

PH value in the range of (0-3) indicates strongly acidic,

PH value in the range of (4-6) indicates weakly acidic,

PH value in (7) indicates a neutral position,

PH value in the range of (8-10) indicates weakly alkaline,

PH value in the range of (11-14) indicates strongly alkaline.

**7. Use of percentage:**

In the textile **dyeing** industry, “percentage” is used to express moisture regain, pick-up dyes, and other chemicals during the treatment of textiles. In the ordinary sense, “percentage” means parts per hundred. These parts must be in the same units i.e. grams per hundred grams, mili-liters per hundred mili-liters, kg per hundred kg, etc.

**“Percentage” can be expressed as the below formula:**

Unit of final substance

**……………………………………………… ×** 100** =** % final substance based on the original weight

Unit of the original substance

**8. Parts per total amount:**

This expression is specially used in textile **printing** recipe calculation. It indicates “how many parts are in the total number of parts?” It can also be expressed by “ parts per hundred parts of total”.

*The relation is in the below:*

{(Parts/total)× 100}= amount%

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