PRIMEASIA UNIVERSITY

Mordant Dyes

Faisal Ibn Haque

3/1/2010

Assignment on Mordant dyes(web collection)

2010

Mordant Dyes:

The term mordant is derived from the Latin moreo, which means to bite or to take hold of. The mordant dye is attached to the textile fiber by a mordant, which can be an organic or inorganic substance. The most commonly used mordant is inorganic chromimum. Other inorganic mordants, such as aluminium, copper, iron, and tin and organic mordant, such as tannic acid , are rarely used. Since chromimum is used so extensively , mordant dyes sometimes called the chrome dyes.

Fibers most readily dyed with mordant dyes are the natural protein fibers, particularly wool; and sometimes the synthetic fibers modacrylic and nylon. (01)

Mordant dyes can be defined as those dyes that requires a mordant for application as a dye. This upon combining with a mordant imparts insoluble colour on the substrates. The question now is what is a mordant? A mordant can be a substance of organic or inorganic nature that can combine with the coloring matter and is used for fixing in the production of the color.

Most of the natural dyes in use are mordant dyes. The Colour Index classification and naming system of mordant dyes would be like this- mordant + base colour + number. Commonly used mordant dye are Hematein (natural black 1), note the numbering system. Other popular mordant dyes are Eriochrome cyanine R (mordant blue 3), Celestine blue B (mordantblue14) and Alizarin red S (mordant red 3).

Chromium salts like sodium or potassium dichromate are commercially used for synthetic mordant dyes. The diagrams below shows C.I. Mordant Black 1 with a chromium (III) ion. (02)

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Features of Mordant Dye:

Mostly mordant dyes have hydroxyl and carboxyl groups. To certain extent they can possess Amino groups.

They are negatively charged, i.e. Anionic.

Mordant dyes stain by ionic interaction like other ionisable dyes.

They ensure light-and-wash-fastness.

Prevents color bleeding.

Has the ability to brighten or changes some dye colors. (03)

Common Dye Mordants:Mordants include tannic acid, alum, urine, chrome alum, sodium chloride, and certain salts of aluminium, chromium, copper, iron, iodine, potassium, sodium, and tin.

Iodine is often referred to as a mordant in Gram stains but is in fact a trapping agent (04)

Dyeing Methods:

The three methods used for mordanting are:

Pre-mordanting (chrome): The substrate is treated with the mordant and then dyed.

Meta-mordanting (metachrome): The mordant is added in the dye bath itself.

Post-mordanting (afterchrome): The dyed material is treated with a mordant.

The type of mordant used changes the shade obtained after dyeing and also affects the fastness property of the dye. The application of mordant, either pre-, meta- or post-mordant methods, is influenced by:

The action of the mordant on the substrate: if the mordant and dye methods are harsh (e.g. an acidic mordant with an acidic dye), pre- or post- mordanting limits the potential for damage to the substrate.

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The stability of the mordant and/or dye lake: the formation of a stable dye lake means that the mordant can be added in the dye without risk of losing the dye properties (meta-mordanting). [05]

Mordant dyes (chrome dyes):

Applicability:

Mordant dyestuffs are generally used for protein (wool and silk). They are practically no longer used for polyamide fibres or for printing.

Properties:

Thanks to their good levelling properties and very good wet fastness after chroming, chrome dyes are used principally to obtain dark shades (greens, blues and blacks) at moderate cost. There are disadvantages, however, in their use: long dyeing times, difficulties with shading, the risk of chemical damage to the fibre during chroming and the potential release of chromium in waste water.

Chemical characteristics and general application conditions:

The Colour Index classifies these colourants as mordant dyes, but chromium has become the almost universally used mordant and the class is commonly referred to as chrome dyes.

From a chemical point of view they can be regarded as acid dyestuffs that contain suitable functional groups capable of forming metal complexes with chrome. They do not contain chrome in their molecule, which instead is added as dichromate, or chromate salt to allow dye fixation.

Interaction with the fibre is established through ionic bonds formed between the anionic groups of the colourant and ammonium cations available on the fibre. In addition chromium acts as a link between dye and fibre. This gives rise to a very strong bond, which is reflected in the excellent fastness obtained. Figure shows the ionic and coordination bonds in the case of wool.

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Figure : Representation of possible ionic and coordination bonds between wool and chrome dyes [69, Corbani, 1994]

The use of chrome dyes in dyeing processes requires the use of the following chemicals and auxiliaries:

potassium and dichromate or chromate formic or acetic acid as pH regulators other organic acids such as tartaric and lactic acid. They are used to enhance the

degree of conversion of Cr VI to Cr III sodium or ammonium sulphate [ 06]

Metachrome Method:

This is one one stage process in which the dye and the mordant are applied to the fiber. This method can only be used with dyes which do not form the dye mordant complex immediately on coming together; that is , the mordant and the dye anion do not form the complex until they have entered the polymer system of the fiber. To minimize the formation of the complex of the dye liquor, the mordant is added and the textile material treated with the dye liquor and temp. raised to about 500 C. At this point the mordant is added and the temp. of the dye liquor raised to the boil for 60 minutes. The method of attachment of the dye to the fiber is the same as for the chrome mordant method.[07]

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After-Chrome Method:

This method involves a two-stage process which reverse of the chrome mordant method. The after-chrome involves the application of the dye followed by mordanting. This method involnes the use of certain mordant dye, which are actually acid dyes which can be mordanted.

The dye are applied to the textile material is a aqueous solution which contain the dye and sodium sulphate. The textile material treated in this liquor by slowly raising the temperature of the dye liquor to the boil where it is kept for about an hour. At this point, the mordant is added and the temperature maintained at the boil for another 45 minutes to one hour. During this period the dye complexes are formed within fiber polymer system; the mode of attachment of the dye to the fiber is the same as for the chrome mordant method.[08]

Properties of mordant dye:

Light-fastness: The light fastness rating of mordant dyes is about 5. The presence of the chromimum in the dye molecule contributes to the very good light fastness of mordant dyed textile material.

Wash-fastness: The wash fastness rating of mordant dyes is about 4-5. The very good wash fastness of textile material dyed with mordant dye is due to the large dye molecules or lakes that are formed within the polymer system.

Dull and limited range of colours:

There is a limited range of colours in the mordant dye class and these are also relatively dull. It is through that it is the presence of the metal chromimum which is responsible for the dullness of colour and the limited colour range.[09]

Effect on the final colour:

Dye results can also rely on the mordant chosen as the introduction of the mordant into the dye will have a marked effect on the final colour.

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Cotton:

Since metallic mordants are soluble in water and are loosely held by the cotton fibres, these mordants have to be precipitated on the fabric by converting them into insoluble form, or by first treating the fibres with oil or tannic acid and then impregnating treated fabric with solution of mordant, whereby the metallic mordants are held on to cotton via oil or tannic acid.

Wool:

Unlike cotton, wool is highly receptive toward mordants. Due to its amphoteric nature wool can

absorb acids and bases equally effectively. When wool is treated with a metallic salt it hydrolyses the salt into an acidic and basic component. The basic component is absorbed at –COOH group and the acidic component is removed during washing. Wool also has a tendency to absorb fine precipitates from solutions; these cling to the surface of fibres and dye particles attached to these contaminants result in poor rubbing fastness.

Silk:

Like wool, silk is also amphoteric and can absorb both acids as well as bases. However, wool has

thio groups (-SH) from the cystine amino acid, which act as reducing agent and can reduce

hexavalent chromium of potassium dichromate to trivalent form. The trivalent chromium forms the complex with the fibre and dye. Therefore potassium dichromate cannot be used as mordant effectively.

Animal and Plant Tissues:

In Histology, mordants are indispensible in adhering dyes to tissues for microscopic examination.

Methods for mordant application depend on the desired stain and tissues under study; pre-, meta- and post-mordanting techniques are used as required.

The most commonly used stain used in diagnostic histology of animal tissues is Harris' haematoxylin as part of a haematoxylin and eosin stain.[10]

Disadvantage of using mordant dyes:

This class of dye is now used to a lesser extent , for the following reasons:

i. Colour matching is difficult as the process of mordanting means that the colour builds up gradually.

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ii. Lengthy period s of application are both detrimental to protein and polyamide fiber and rather costly.

iii. Dichromate salts such as sodium and potassium become pollutants once they are discharge into the sewerage.[11]

Ancient Dyes( red anthraquinonoid mordant dye ):

Techniques for dying ancient textiles were described by classical authors such as Pliny the Elder and Aristotle (Koren 270). Today the Edelstein Center for the Analysis of Middle Eastern Textiles and Related Artifacts at Shenkar College of Textile Technology in Ramat-Gan Tel Aviv specializes in studying those processes and analyzing ancient textile dyes.

People have been dying cloth for at least 6000 years. Archaeologists have found a number of ancient pieces of dyed fabric and other evidence for ancient textile dying. One of the most important finds was a 6000 year-old 23-foot long red-dyed linen cloth that was recently discovered in the "Cave of the Warrior," a major Neolithic site in Israel. Ancient dyed garments were also found at Masada (Orna 373). Sheep’s wool that was dyed red with madder and blue with indigo was found at Kahun, an Egyptian town for pyramid workers, dating to 1890 BC (Bahn 318). Egyptian tomb paintings at Beni Hasan also show nomadic people wearing multi-colored garments and shoes, and a model dating to 2000 BC from the tomb of Meketra at Thebes shows a weaving workshop where cloth was dyed.

Ancient dyes can be classified chemically into three groups: blue and purple indigoid vat dyes, red anthraquinonoid mordant dyes, and yellow flavonoid dyes (Koren Historico).

As seen in Table 2, red anthraquinonoid mordant dyes came from henna and madder. These dyes were water-soluble, so they ran and washed out of fabric unless a mordant was added to fix the dyes. The mordant reacted with the dye to produce a "lake," which was a large chemical complex that was not soluble in water.

As early as 1000 BC, people began to use potassium alum mordants (K(Al(SO4).12H2O) (Salzberg 3). The aluminum ion from the mordant formed a large complex with madder that was brick-red in color and

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would not wash out of fabrics (Cronyn 286). By using different mordants of chromium, tin, and iron salts, ancient dyemakers could make chocolate-purple and pink complexes (Orna Coordination 175). Acidic mordants, such as tannic acid (gallotannic acid) were also used (Koren Historico 272).[12]

Environmental issues:

The environmental properties of chrome dyes are assessed under the following parameters. Note, however, that does not consider the environmental issues related to chemicals and auxiliaries employed in the dyeing process because these issues are dealt with in a specific annex.

Parameters of concern:

Bio-eliminability Organic halogens (AOX) Eco-toxicity Heavy metals Aromatic amines Unfixed colourant Effluent contamination by additives in the dye formulation[13]

What's the difference between mordants and other chemical assistants used in dyeing?

Sodium carbonate is not a mordant! Neither are vinegar or salt. A mordant is a metal ion which attaches to the fiber, usually by being boiled together for a length of time. A dye which has no natural attraction to the fiber can then attach to the metal ion. Most but not all natural dyes are mordant dyes, which require the metal ion to be in the fiber in order for them to have any attraction to the fiber. There are also some synthetic dyes that are mordant dyes.

Mordants include alum, chromium, copper, iron, and tin. Some of these metals are quite toxic and hazardous, in addition to be environmentally damaging. Chromium is the most hazardous of mordants. The hexavalent form of chromium, in potassium dichromate, which called for in some recipes, is a known human carcinogen. Alum is the least toxic of the mordants, though it can be irritating and should be used with care.

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Tannic acid is another important mordant, a large, complex, metal-free molecule, used mainly in dyeing cellulose fibers, such as cotton. Tannic acid can be obtained from many plant sources, such as the galls on oak trees. A typical recipe for using tannic acid as a mordant calls for boiling cotton first with alum, then tannic acid, then alum again, each in a separate boiling water bath, followed by boiling with the mordant-requiring dye. I think that the alum attaches to the cotton, the tannic acid attaches to the alum, and the dye attaches to either the tannic acid or to another alum ion attached to the tannic acid. This is much more complex, and much less resistant to washing out, then the bonds formed by reacting a modern synthetic fiber reactive dye directly with the fiber.

Most synthetic dyes have no requirement for mordants. Fiber reactive dyes, such as Procion MX dye, have no need whatsoever for a mordant, because they form chemical bonds directly to the fiber. The dyeing process for these other dyes does make use of other chemicals, but not mordants. In some cases a mordant will improve the washfastness of an acid dye on wool, but there is no need to use a mordant with most synthetic acid dyes.

A low pH is useful for dyeing protein fibers such as wool, and a high pH is useful for dyeing cellulose fibers with reactive dyes. In neither case is this achieved by using a mordant. Instead, pH-adjusting chemicals (which are NOT mordants) are used, such as sodium carbonate or vinegar, though they have opposite effects from each other and are used on different fibers.[14]

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SOME EXAMPLES OF HOW USING MORDANTS CAN AFFECT MUSHROOM DYE COLORS:

SOME EXAMPLES OF HOW USING MORDANTS CAN AFFECT MUSHROOM DYE COLORS

MUSHROOM SPECIESNo Mordant(“ no knot “ )

Alum Mordant(“ 1 knot “ )

Iron Mordant(“ 5 knots “ )

Phaeolus schweinitzii

light yellow gold burnt sienna

Dermocybe phoeniceus var. occidentalis

pink rose maroon

Omphalotus olivescens

lavender purple dk.forest green

Ref: International Mushroom Dye Institutes

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List of MORDANT DYES

Sr. No. Colour indicators DYCROCHROM C. I. NAME

1YEL

LOW GMORDANT YELLOW 1

2 YELLOW H MORDANT YELLOW 10

3 ORANGE G MORDANT ORANGE 6

4 RED WR MORDANT RED 3

5 RED B MORDANT RED 7

6 BRILL RED BR MORDANT RED 15

7 BROWN R H/C MORDANT BROWN 33

8 GREEN G MORDANT GREEN 17

9 BLACK A MORDANT BLACK 1

10 BLACK T MORDANT BLACK 11

11 BLUE BLACK RSS MORDANT BLACK 17

[15]

Ref:[15] JAGSON COLORCHEM LIMITED

CHROME AND CHROMATES by Dr. Erik Sundström, Sweden

Sodium or potassium dichromates have been suggested as mordants, ever since they were used with the first synthetic mauvein dye in 1856. Potassium dichromate was preferred, since sodium dichromate absorbs moisture and becomes slimy. The dichromates are orange to brownish red and will stain the wool themselves without helping the natural dyes to fasten, and they may produce interesting color combinations.

Water soluble chrome compounds are generally either green chrome(III) salts where the chrome is the positive ion, or chromates where the negative ion is chrome(VI) with oxygen. Chromates were once regarded as innocent and even tried as medicines, but in the 1970's they were found to be so dangerous and the occupational health regulations became so severe, that they may only be handled in closed systems by personnel in full protective suits.

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The main reason is that the cells of our body are only prepared to handle water soluble ions of the kinds occurring in nature. This means among negative ions: carbonate, sulphate, chloride and hydroxyl, but not chromate, and among positive ions hydrogen, ammonia and most metals except lithium, caesium and some of the heaviest like lead, cadmium or mercury. The cell walls will keep an equilibrium by shuttling sodium, potassium, magnesium and calcium back and forth, and failure to do so leads to nervous problems. Among other metals, iron is needed for blood and muscles in rather large amounts, and zinc in small amounts for tissue repair. Metals which could be mistaken for iron must be kept out so as not to disturb the iron process, and among them are copper and chrome, and tin will be kept out so it will not be mistaken for zinc.

There is no defense against chromate ions, however, since they do not occur in nature, and they can easily enter into the cells. Once they get in, they can attach as mordants to protein to make it water repellent. Chromates are also strongly oxidizing with their oxygen burning or breaking other cell component.. When this occurs, chrome(VI) turns to chrome(III) which disturbs the action of iron. By then the immune system becomes aware that something is wrong, but has no indication of any dangerous stuff passing through the cell membrane, so it starts looking for some probable enemy to fight. You may then become allergic to something close-by, but not chromates. If you are a dyer you might become allergic to wool, a tanner might be allergic to leather, etc. Chromates are also carcinogenic and may start fires. They will also disturb the micro-organisms in water purification plants, so it is not permitted to dump chromates in the drains.

(Dr. Erik Sundström, has a Doctorate in the Science of Materials and is a Mycologist. He is co-author of"Färga med svampar", and the author of a new Swedish book about pigments of Natural Dyes.)

Manufacturer(mordant dye):

ReferenceProducer

Cas Numberor

Colour Index

ORANGE BLACK POUR CUIR SOLIDE TU 141 %

BAYER

DIAMANT BLUE FBG BAYER MORDANT BLUE47

DIAMANT BLUE SOLIDE BL 133% BAYER MORDANT BLUE7

DIAMANT ORANGE BLUE FBG BAYER

DIAMANT ORANGE RED SOLIDE BL BAYER MORDANT RED30

DIAMANT ORANGE RED SOLIDE BT BAYER MORDANT RED74

DIAMANT ORANGE BROWN R 154 % BAYER

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DIAMANT ORANGE BROWN SOLIDE TBL

BAYER MORDANT BROWN21

DIAMANT ORANGE MARINE RRS BAYER

DIAMANT ORANGE ORANGE GR BAYER MORDANT ORANGE6

DIAMANT ORANGE GREEN B BAYER MORDANT GREEN25

DIAMANT MARINE RRN BAYER

DIAMANT BLACK KW BAYER

DIAMANT BLACK PLC BAYER MORDANT BLACK8

DIAMANT BLACK PV 200 % BAYER MORDANT BLACK9

DIAMANT RED SOLIDE 3BG BAYER MORDANT RED63

ORANGE BLUE SOLIDE R CIBA

ORANGE ORANGE 2G CIBA MORDANT ORANGE23

ORANGE RED SOLIDE BL CIBA MORDANT RED33

ORANGE RED SOLIDE GR CIBA MORDANT RED40

ERIOORANGE BLUE 2GK CIBA MORDANT BLUE49

ERIOORANGE BROWN DKL CIBA MORDANT BROWN19

ERIOORANGE BROWN DKL 150 % CIBA MORDANT BROWN19

ERIOORANGE BROWN FONCE R CIBA MORDANT BROWN27

ERIOORANGE BROWN K CIBA MORDANT BROWN15

ERIOORANGE FLAVINE 3R CIBA MORDANT YELLOW8

ERIOORANGE FLAVINE 3R 150 % CIBA MORDANT YELLOW8

ERIOORANGE FLAVINE A CIBA MORDANT YELLOW5

ERIOORANGE GRIS A2BL CIBA

ERIOORANGE YELLOW O CIBA MORDANT YELLOW34

ERIOORANGE BLACK AZ CIBA MORDANT BLACK1:1

ERIOORANGE BLACK BLUE B CIBA MORDANT BLACK3

ERIOORANGE BLACK BLUE RSS CIBA MORDANT BLACK17

ERIOORANGE BLACK BLUE RSS 140%

CIBA MORDANT BLACK17

ERIOORANGE ORANGE R 165 % CIBA MORDANT ORANGE6

ERIOORANGE RED G CIBA MORDANT RED17

ERIOORANGE RED PE CIBA MORDANT RED9

ERIOORANGE VERDON S CIBA

ERIOORANGE GREEN BL 180 % CIBA

ERIOORANGE GREEN BRILLANT CIBA

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BL

ERIOORANGE VIOLET BRILLANT B CIBA MORDANT VIOLET28

ERIOORANGE VIOLET BRILLANT B 300 %

CIBA MORDANT VIOLET28

NAPHTOORANGE AZURINE B CIBA MORDANT BLUE28

CHROMAZURINE NB NEW CONCCLARIANT SANDOZ

LUXINE ORANGE YELLOW PUR 6GCLARIANT SANDOZ

METOMEGA ORANGE BROWN RLLCLARIANT SANDOZ

MORDANT BROWN63

METOMEGA ORANGE GRIS GLCLARIANT SANDOZ

MORDANT BLACK38

METOMEGA ORANGE GREEN BLLCLARIANT SANDOZ

MORDANT GREEN29

NOVOORANGE RED GRCLARIANT SANDOZ

MORDANT RED68

OMEGA ORANGE AURINE GLSCLARIANT SANDOZ

MORDANT YELLOW6

OMEGA ORANGE BROWN EBCLARIANT SANDOZ

MORDANT BROWN1

OMEGA ORANGE ORANGE G CONCCLARIANT SANDOZ

MORDANT ORANGE6

OMEGA ORANGE RED BNCLARIANT SANDOZ

PANDURANE YELLOW 2RLCLARIANT SANDOZ

PANDURANE BLACK PTCLARIANT SANDOZ

POLYTROPE BLUE RCLARIANT SANDOZ

ANTHRACENE TURQUOISE DIVERS

ORANGE BLUE L2878 DIVERS

ORANGE BLUE SOLIDE GRA DIVERS

ORANGE BROWN SOLIDE RL DIVERS

ORANGE MARINE 3R 75 % DIVERS

ORANGE VIOLET 2R EXTRA DIVERS

ORANGE VIOLET 4B DIVERS

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PONTAORANGE BLACK BLUE RM CONC

DUPONT MORDANT BLACK17

ORANGE BLUE 2JICI FRANCOLOR

ORANGE BLUE BRILLANT 3RICI FRANCOLOR

ORANGE FLAVINE SOLIDE JICI FRANCOLOR

MORDANT YELLOW5

ORANGE GRIS SOLIDE BRLICI FRANCOLOR

MORDANT BLACK79

ORANGE YELLOW JSNICI FRANCOLOR

MORDANT YELLOW34

ORANGE YELLOW SOLIDE J2RLICI FRANCOLOR

ORANGE ORANGE SOLIDE RLICI FRANCOLOR

MORDANT ORANGE3

ORANGE RED SOLIDE JICI FRANCOLOR

MORDANT RED17

ORANGE RED SOLIDE NLICI FRANCOLOR

MORDANT RED94

ORANGE RED SOLIDE NL 50 %ICI FRANCOLOR

MORDANT RED94

ORANGE GREEN NICI FRANCOLOR

MORDANT GREEN36

ORANGE GREEN SOLIDE BICI FRANCOLOR

ORANGE VIOLET RICI FRANCOLOR

MORDANT VIOLET5

ORANGE VIOLET RLICI FRANCOLOR

MORDANT VIOLET44

FRANCOLANE BLACK BLUE RFICI FRANCOLOR

MORDANT BLACK17

FRANCOLANE ORANGE 2RICI FRANCOLOR

SOLOORANGE BLUE FONCE BICI FRANCOLOR

MORDANT BLACK17

SOLOORANGE BLUE RHICI FRANCOLOR

SOLOORANGE BROWN RH ICI MORDANT BROWN33

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FRANCOLOR

SOLOORANGE YELLOW OICI FRANCOLOR

MORDANT YELLOW34

SOLOORANGE MARINE BFDICI FRANCOLOR

SOLOORANGE MARINE BNDICI FRANCOLOR

SOLOORANGE ORANGE RICI FRANCOLOR

MORDANT ORANGE3

SOLOORANGE VIOLET RICI FRANCOLOR

MORDANT VIOLET16

VERILAN GRIS 2BSICI FRANCOLOR

ORANGE GRIS B 85 %SAIA / SACOLOR

ORANGE YELLOW R 125 %SAIA / SACOLOR

MORDANT YELLOW8

ORANGE YELLOW R 55/180SAIA / SACOLOR

MORDANT YELLOW8

ORANGE MARINE 2BSAIA / SACOLOR

ORANGE MARINE 2B 135/170SAIA / SACOLOR

ORANGE RED BG 70 %SAIA / SACOLOR

MORDANT RED9

CHROMACIDE BROWN SOLIDE 2R STEINER MORDANT BROWN33

CHROMACIDE MARINE SOLIDE B STEINER

CHROMACIDE BLACK BLUE SOLIDE RF EXTRA

STEINER MORDANT BLACK17

CHROMACIDE ORANGE SOLIDE N STEINER MORDANT ORANGE1

CHROMACIDE RED ECB STEINER MORDANT RED7

CHROMACIDE VIOLET SOLIDE R STEINER MORDANT VIOLET5 [16]

Ref: 01.Textile Science_E.P.G. GOHL & L.D. Vilensky

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02&03. www.dyes&pigments.com .

04&05. www.answers.com/topic/mordant

06. unknown source

07. Textile Science_E.P.G. GOHL & L.D. Vilensky

08. Textile Science_E.P.G. GOHL & L.D. Vilensky

09. Textile Science_E.P.G. GOHL & L.D. Vilensky

10. www.answers.com/topic/mordant

11. Textile Science_E.P.G. GOHL & L.D. Vilensky

12. Cronyn J. M. The Elements of Archaeological Conservation. London: Routledge, 1990.

Koren, Zvi. "Historico—Chemical Analysis of Plant Dyes Used in Textiles from Ancient Israel." Archaeological Chemistry: Organic, Inorganic, and Biochemical Analysis. Washington DC: American Chemical Society, 1996.

Salzberg, Hugh W. From Caveman to Chemist: Circumstances and Achievements. Washington D.C.: American Chemical Society, 1991.

Orna, Mary Virginia. " Doing Chemistry at the Art/Archaeology Interface." Journal of Chemical Education vol. 74. Apr. 1997: 373-6

Orna, Mary Virginia, Adrienne W. Kozlowski, Andrea Baskinger, and Tara Adams. "Coordination Chemistry of Pigments and Dyes of Historical Interest." American Chemical Society, 1994.

13. unknown source

14. http://www.pburch.net/dyeing/FAQ/mordants_and_assists.shtml

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