the word mordant has its origin in the french language

8/3/2019 The Word MORDANT Has Its Origin in the French Language

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ASSIGNMENTFROM:- FAIZ BADAR VASIFEP#:- 094203TEXTILETO:- MAM WASIYA.B.S 3 rd YEARAPPLIED CHEMISTRY EVENINGSUBJECT:-MORDANT DYES.

MORDANT WORD ORIGIN The word MORDANT has its origin in the French language, meaning

"to bite." Mordants are basically mineral salts which binds dyes

into fiber. Over the years many amazing substances were applied

as mordants. That includes arsenic and many other deadly

chemicals.

Mordant Dyes

These are special acid dyes in which certain metal atom can be introduced

during dyeing. These are water soluble dyes and affinity for silk, wool and

polyamides. Mordant dyes require a mordant in their application and thesedyes upon combination with the mordant deposit on the fiber in the form of

insoluble color. Most commonly dyes have hydroxyl or carboxyl groups and

are negatively charged (anionic) in nature.

Properties of mordant dyes1) These dyes are economical dyes and are generally used to produce dark

shades such as dark greens, dark blues and blacks.

2) The interaction between fiber and dye is established through very strong

ionic bonds, which are formed between the anionic groups of the colorant

and ammonium cations on the fiber. Chromium or the metal ion acts asbridge between the dye and fiber , which gives rise to a very strong

linkage , resultinginto excellent fastness properties.

3) Mostly mordant dyes have hydroxyl and carboxyl groups. To certain

extent they can possess amino groups.

4) They are negatively charged, i.e. Anionic.

5) Mordant dyes stain by ionic interaction like other ionisable dyes.


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6) They ensure light-and-wash-fastness

7) Prevents color bleeding.

8) Has the ability to brighten or changes some dye colors.

Mechanism of dyeingSince these are a special class of acid dyes , which are soluble in water

andapplied to the fiber from an acidic bath. When a solution of an acid

mordant dye is mixed with a solution of potassium dichromate in the

presence of sulfuric acid , chromium ion from dichromate forms a complex

with the dyes , this complex is insoluble in water ,and hence precipitates on

the fiber.

There are three different methods of application of chrome dyes on thefiber,

Chrome Mordant method

After chrome method

Meta chrome method

Application of mordant dyesChrome-mordant processIn chrome mordant process, the fiber is first treated with potassium

dichromate in the neutral bath or in the presence of either sulfuric or formicor oxalic acid. When sufficient amount of chromium is taken up by fiber , it

is taken out , squeezed and entered in the dye bath containing acid mordant

dye. The dye form an insoluble complex with chrome present on the fiber .

After chrome methodIn this method the substrate is first treated with the dye , the dye is exhausted

by the addition of an acid , and after complete exhaustion the material is

taken out squeezed and then run in a solution containing potassium

dichromate and an acid. Metal dye complex is formed on the fiber , which isinsoluble.


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Meta Chrome processThis is a single bath process , in which the material is treated with in a bath

containing acid mordant dye , potassium dichromate and ammonium

sulphate.The dye along with potassium dichromate and ammonium sulphate got

absorbed by the fiber and evenly distributed but no complex is formed

because the pH is not suitable for the chemical reaction to take place.

In the second step of the meta chrome process, when the dye bath is heated ,

ammonium sulphate is converts into ammonia and sulphuric acid , which

makes the bath strongly acidic and potassium dichromate in the presence of

strong acid now react with the dye molecule forming an insoluble complex

on the fiber.

Most commonly used mordant dye The most commonly usedmordant dye is undoubtedly hematein (natural black 1), whose status as a

natural product supercedes its mode of dyeing, apparently. Others are

eriochrome cyanine R (mordant blue 3) and celestine blue B (mordant blue

14), both used as substitutes for alum hematoxylin but with a ferric salt as

the mordant. Alizarin red S (mordant red 3) is valuable for the demonstration

of calcium, particularly in embryo skeletons.

REFRENCE:-

*http://dyeingworld1.blogspot.com/2010/01/mordant-dyes.html

*http://dyes-pigments.standardcon.com/mordant-dyes.html

*http://www.jagson.com/mordant_dyes.htm
http://dyeingworld1.blogspot.com/2010/01/mordant-dyes.htmlhttp://dyes-pigments.standardcon.com/mordant-dyes.htmlhttp://www.jagson.com/mordant_dyes.htmhttp://dyeingworld1.blogspot.com/2010/01/mordant-dyes.htmlhttp://dyes-pigments.standardcon.com/mordant-dyes.htmlhttp://www.jagson.com/mordant_dyes.htm

the word mordant has its origin in the french language

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