LEATHER DYEING-LEATHER DYEING PRACTICES BY EGEMEN AKTAS

REPORT OF DYEİNG PRACTİCES

BY;EGEMEN 

DYEİNG

Aims:

Aim of vegetable dyeing: From a direct dye, observe how different influence on the charge-exchange intensity, pitch, equalization, the affinity to the skin, the power of penetration and degree of fixation of the dye

Aim of dyeing crust: See the differences between a wet-blue dye on and on crust.comparar two dyesystems: crossed and crossed and see how they influence different load changers on the intensity, hue, equalization, the affinity to the skin, power of penetration and degree of fixation of the dye.

Aim of dyeing vegetal: See the differences between a set of chrome dye skins and furs to the plant.Compare two dye systems: crossed and crossed and watch changers chargedifferent influence on the intensity, hue, matching, affinity to the skin, penetrating power and the degree of fixation of the dye.

THEORİCAL PART:

Leather dyeing is a transition process between tanning and finishing. Some kinds of leathers requirepenetration of dyestuff into collagen network while certain kinds of leather need not be dyed through, it is enough to dye them on the surface. This decreases consumption of dyestuff, which is an expensive material. It is important to know how penetration of dyestuff proceeds. The processes done affect the chemical properties of leather.The result of dyeing is not only dependent on tanning agent and method used, reactions of fat, surfactant and water should also be taken into consideration.
There are some characteristics are required from a dyeing.These are ;

Levelling: Dyed leathers must have homogeneity.

Lightfastness:  Different dyes have different degrees of resistance to fadding by light.All dyes have different susceptibility to light damage because their strong colours are indications that they absorb the wavelengths that they dont reflect back.Light is an energy,and the energy that is absorbed by pigmented compounds may serve to degrade them or nearby molecules.

Fastness to migration : migration is a mistake of dyeing.İt means unhomogenius dyed leathers.

Stability to cleaning:  customers expect more stability  of cleaning from leather goods. Not enough fixation can be as a result.

Buffing fastness: finishing operations are improve the appearance of the dyeing. Properties of dye determine this property

Fastness to sweat: İts more important for clothing leathers which touches directly to skin.For these leathers leather dye must be resistant to sweat.

Dry and wet rubbing fastness: Assessment of the resistance of the finished leather surface to abrasion, scuffing and staining.. This problem is important in upholstery and shoe leathers.

 Washing fastness : Under ideal conditions all the dye offered is fixed to the leather, and subsequent washing of the dyed leather with water should not wash off any color. The dyeing is then said to be 100% wash fastness. 

Dyestuffs are soluble organic substances in acid, neutral or basic media with an unsaturated molecular structure (they are electronically unstable).  Dyestuff consists of two parts:

Chromofore part : This part is determine the colour in dyestuffs. These are 

nitro group, tiyacarbonil group ,azo group, carboxyl group ,nitrozo group                                                     ethylenic double bond group

Auxochrome part:  This part  relevant  that   dyestuff  dissolution  in the water.

Amine group,Tertiary amine group,Hydroxyl  group,Charboxyl group,Methoxyl group                                                     Seconder amine

                                                                                            

Types of Dyestuffs

–        Anionic dyestuffs:   .We use anionic dyestuffs  commonly wet blue tanning or cationic treatment in pretanning on vegetable tanning or synthetic tanning .For better penetration Ph must be under 4. İt has 2 subtittle:

•          Simple acid dyestuffs: particle size is small, low cost, good penetration, clear bright colours  but  low lightfastness , sweat fastness, washing fastness and clean fastness.

•          Direct dyestuffs:  also called substantive dyestuffs   they dye protein fibres, good covering  surface ( if the leather has stain or another problem on surface  this dyestuff  covers.) better penetration  on suede leathers .

–        Basic dyestuffs: They called ‘’ cationic dyestuffs’’   If we use these dyestuffs , Leathers must be negative charge  on retanning process.  The properties of basic dyestuffs : higher covering,  brightly tones , but low lightfastness, low dry or wet rubbing fastness . In addition  we can use  basic dyestuff with sandwich  dye system.

–        Metallic complex dyestuffs: There is 2 types of methallic complex dyestuffs.

–        1.1 Methallic complex dyestuffs : Better  lightfastness , good washing fastness . We use them for clothing leathers or glove leathers. If ph  under  5 and high temperature  we dont have good dyeing.

–        1.2 Methallic complex dyestuffs: Good lightfastness, good washing and wetting fastness.But homogenity is low and  not enough penetration.

–        Reactive dyestuffs: Usually using wool and cotton  or pollyamid fibres . dry-cleaning fastness lightfastness  and migration fastness is good. We can use at low tempreratures for dyeing with reactive dyestuffs.

–        Dispersing dyestuffs: Generaly using in  synthetic fibrils dyeing ( wool and fur products ) They have hydrofobic  characteristic. Low dissolving in water( need more grind)

–        Sulphur dyestuffs:  Generaly using in chamois and lining leather dyeings.  All fastnesses are high  and low cost . In addition   they give matt colours (not bright) 

•         Several characteristics are required from a dyestuff:

•          Fastness to alkalis : we should choose suitable  dyestuff  (stability to alkalis)

•          Performance: If we  use  same  dyestuuf have same properties  so their characteristics  be same so we can have better performance in dyeing.

•          Fixation: important for  washing fastness ,  cleaning fastness.

•          Homogenity:  for good appearance .

•          Intensity: it depends on colour  variations.

•          Stability to hard water : if not stabil than can occur stains on surface

•          Stability to acid : stability to formic acid or sulphric acids is important.

•          Solubility:  water rate is important.  For example 1/5 ,     1/ 4 water rate. And suitable temperature. Firstly cold solution (emulsion of dyestuff ) and add hot water. We don’t want precipitation

Phenomena occurring in dyeing:

Collagen contains functional groups, part of them bound in  the tanning process, and tanning agents which may possibly react with dyestuffs: in a vegetable leather these may be sugars and phenols and in mineral tanned leather these may be complexes of chromium or other metals as well as fats, surfactants or proteins. Isoelectric point of collagen lies in the range of 7-7.8 pH, that of chrome tanned collagen 6.5 pH, of vegetable tanned one 3.5pH, aldehyde, quinone and oil tanned about pH 4.5. It is essential to choose dyestuffs so as to ensure opposite charges on both substances.

1. Factor influencing in the dyeing:

–        Tanning temperature: at high temperature (60°C)

–        Tanning pH: this affects the dissociation of the charged groups on the dye and on the leather. an anionic dye in acid pH will tend to "switch off" its charge. If in the presence of a cationic group in the process of being "switched on" it will tend to form a salt-link. In the case of direct (anionic) dyes, the molecules are so large that salt-linkage is relatively unimportant, fixation taking place between pH 4-7.                      

              

–        Volume of retanning pH : Higher pH , lower penetration.

–        Temperature of retanning float : temperature causes fixation faster.

–        Water: we must use soft water. If we don’t want precipitation.

–        Dyestuff selection  :  Dyes that are used together in a dyeing formulation must be combinable with each other, as otherwise unlevel shades will result.Combinability is dependent onchemical structure,absorption rate of dyes,build-up properties of dyes,kind of retanning.

–        Amount of dyestuff:  it depends on  characteristic of dyestuff

–        Addition of dyestuff : more dyestuff ,  more washing and more formic acid .

–        Volume of dyeing float:  Effects   penetration directly . lower  volume  makes better cross section of dyeing.

–        Dyeing temperature: High dyeing temperatures increase the affinity and absorption rate of dyes (may impair levelness of resulting shades on retanned leathers) and improve fixation of dyes.Low dyeing temperatures promote distribution of dyes during dyeing process and reduce fixation of dyes.The optimum procedure is to maintain a low temperature (30 °C) at the beginning of the dyeing process and a high temperature (> 50 °C) towards the end of the dyeing process to fix the dyes.

–         Mechanical effect: Makes penetration better.

–        Dyeing time: İt depends on dyestuff selection and amount of dyestuff and addition of dyestuff

–        Dyeing pH : It depends on types of dyestuffs.

–        Addition of auxiliary products : acceleration  dyeing time

–        Dyestuff fixation: we have fixation with formic acids.

–        Fatliquoring  : Higher sulfited or sulfochlorinated fatliquors may reduce the absorption properties and/or cause stripping of dye.Depending on the kind and amount of emulsifying components, improved penetration and levelness of shade can be achieved with reduced depth of shade

DYEING METHODS

–           Sandwich dyeing:  Depth of shade is improved by adding acid or cationic dyeing auxiliary between two dye additions.

–        Dyeing without float: Effects accelerated penetration. To achieve good levelness of shade the temperature should not exceed 25 °C. Disadvantages;  may ocur damage from mechanical effect because short float,  %10 less colour power with same amount dyestuff.  %20 dyestuff consumption.

–        Dyeing with intermediate drying: if we produce leathers for  more using. We can dyeing this method. Because, one  time dyeing before the intermediate and after once again.

–        Basic dye topic:  Advantages; perfect covering of the  surface ( don’t  allow to have stains or mistakes on leather ), gives  special effects and better bright colours.Disavantages; hard egalisation , low lightfastness, low rub fastness,if  we use more amount of  dyestuff   that  blocked finishing layer.

–        Special effects:  we use  suitable  dyestuffs for together use same float same emulsion . we don’t want to precipitation. We have to have suitable temperature and right  water rate.

•         Dyeing process control:

   -pH:  we should prepare leathers in retanning and neutralisation  for suitable ph for better dyeing . We first gona have penetration then fixation. And we use acid for decrease the ph that tend to fixatıon.After dyeing Ph of the  leather should be between ph  3.8 -4.2 .

   -float exhaustion : we  must look to float carefully. Dyestuff must be penetrate in to the leather.

   -thorough dyeing of the leather : after washing , leathers  should not  leave dye on hand. And leather should have absorbed all dyestuff from the float. We don’t want  dyeing mistake on surface.In addition , we have to observe homogeneity.

DYEİNG WET-BLUE

MATERIAL AND PRODUCTS

We use  wet-blue  leathers for first practice. Wet blue leathers have to storage suitable conditions. we usually packed in plastic prior to send them out or  before start next processes.Inaddition, during the course of storage, it is subjected to fungi and yeast attack and this causes stains which are sometimes difficult to remove. When we process chrome tannage leathers  we have to control same parameters and should do some mechanical operations. For example; the first thing to learn is the final temperature of tannage, the pH index of the chrome tannage float, storage time, content in water of the wet-blue and the shaving thickness of the wet-blue.

•          To obtain leather goods from leathers in the wet-blue state, the following processes have to be carried out:

–        Sorting and shaving : we want to  choose suitable  and same quality leathers and remove the unneccessary water  inside of the leather and adjust  thickness.

–        Washing: we remove  unfixated chrome and prepare leather for  next processes.

–        Neutralisation : we aim to get the  suitable ph  for retanning  , dyeing or fatliquoring  .  Shortly , we change to pI ( izoelectiric point) for good penetration .

–        Retanning : we  can add different tanning materials to develop leather properties and get properties from th leather we want.good touching .

      

There are different methods to carry out the dyeing: A direct dyeing, dyeing without float and sandwich system.

•          The products that can work as charge changers are:

–        formic acid: is the simplest carboxylic acid. Its chemical formula is HCOOH . we usually use with 1/10  dillution rate  . we use formic acid  in several processes. Fixation  of  dyestuffs ,  pickle etc .

–        aluminium sulphate : is a chemical compound with the formula Al2(SO4)3. resistant to water and with adequate hydrothermal stability aluminium gives strength for leathers and  relevant with  shrinkage  temperature and  developing appearance of dyeing on surface shortly, gives homogeneity dyeing on surface with slow penetration. we have bright tones.

–        aluminium sulphate with different combinations with formic acid

–        cationic oil:  cationic lubricants are more resistant to change in pH . Different type of products has different effects on leather.

–        chrome salt with 33 % basicity  : most common using  basicity  chrome.  There are  only one OH  group İn its structure.so that  it occurred slowly  and deeply penetration.

–        aluminium chloride:Formula is  AlCl3H2O compound with aluminum hydrochloride  it gives firmed leathers.

DYEİNG CRUST

•          Crust leathers  dried leathers that  could  be chrome tanned or vegetable tanned or combined , fatliqoured and  treated mechanically without finishing  operations. There is not so much fungi and yeasts attack  as  wet blue storages cause of dry conditions. İn crust leathers we have to know source of the rawstocks and the operations they have been subjected to since chrome oxide content, type and amount of vegetable extract, fat percentage and pH may vary considerably from one source to another. Generally , crust is delivered by sorted amounts and thicknesses. However, it is necessary to do a eye check of their general state, and especially of the conditions of surface absorption.

•          Before the starting  process   leathers must be soaked a period of time that   it depends on  fibrils. We have to give naturel humidity on leathers with  this way.

•          The results of the dyeing will highly depend on how the leathers have been previously treated:

–        Type of tannage : it is possible  wet blue , vegetal or combined . these tannage variations effect to crust leathers.

–        Neutralisation :   we have to work suitable and optimal ph. Chemicals and leather ph must be equal.

–        Type of retannage : It depends on  what kind of leathers we want.

                     Type of fatliquor applied: we can use  sulphone , sulphate or sulphite oils or combined  among of them. It depends on softy or firmed.

          DYEİNG VEGETABLE LEATHERS

•          Vegetable tannage, the isoelectric point of collagen is approximately at pH = 3.4 – 4. The leather will show a propensity for combining with cationic or basic dyestuffs. These will grant full, bright dyeings with good covering power, but with poor levelling. In addition, their excessive use may result in bronzing (i.e. metallic reflexes). Anionic dyestuff preffered to cationic dyestuff cause of their sudden combination and ease of stressing leather defects only except top dyeing is preffered.The most suitable dyestuffs are sulphonated triphenylmethane. These dyestuffs have an amphoterous character, give full and homogeneous dyes without stressing the defects of the leather and without precipitating with the tannins.

•          Fats have to be emulsified and redistributed across the leather using tensioactives, emulsifiers and synthetic products.Resinified tans have to be removed and replaced by new tans. Since vegetable tanned leather has a reduced reactive power against anionic dyestuffs, in most cases it is not necessary to add auxiliary products .In order to fix the dyestuffs, the pH has to be sufficiently decreased to remain below the isoelectric point.

     

BIBLIOGRAPHY

·         Deri boyaları ve boyama tekniği- Prof.  Özcan SARI, Yard. Doç Dr Mehmet Mete MUTLU

·         TOPTAŞ Ahmet, Deri Teknolojisi, T.C.İstanbul Üniv. Tek. Bil.Yük.Okulu

Öğr.Gör. Erdiz Masa Üstü Yayıncılık 1993-İSTANBUL

·         http://www.buzzle.com/articles/leather-dyeing-how-to-dye-leather.html

·         http://www.swystemlogic.com/swystem/leather_dyeing.htm

•         http://www.tfl.com/web/files/whatareleatherdyestoday.pdf

·         http://www.wikipedia.org/

EXPERİMENTAL PART

1-WET-BLUE DYEİNG

Wet-blue: name that is known to all chrome tanned skins wet.

Objectives: as a direct dye, observe how different changers load influence on the intensity, hue, matching, affinity to the skin, penetrating power and the degree of fixation of the dye.

Operating Method: In a large piece of wet-blue leather lavage is performed, neutralized and retanning. From here, is to compare different dyes, so that small pieces were cut 8 to make the 8 practices described below.

Load Changers to compare: formic acid, aluminum sulfate, aluminum sulfate withdifferent combinations with formic acid, oil cationic chromium salt basicity and 33%aluminum chloride. All these products can act as load changers, and each providesdifferent results in the same dye.

Practice 1: Direct Dyeing

Skins: wet-blues


Washing: 200% Water at 35 ° C
0.2% formic acid (1:10)
Roll 10 minutes.
Drain bathroom.
Neutralized: 150% Water at 35 ° C
1% sodium formate (1:10)
1% sodium bicarbonate (1:20)
Roll 1 hour. Look pH. Drain bathroom.
Retanning: 150% Water at 40 ° C
2% anionic polymer retanning
Roll 40 minutes.
Mimosa 3%
3% synthetic phenolic retanning
Roll 45 minutes.
Drain the bath.
Dye: 150% Water at 50 ° C
1% Dye
Ride 30 minutes.
0.2-0.4% formic acid
Roll 20 minutes.
Look pH.
Drain bathroom.

Practice 2: Dyeing sandwich with different load changers

Skins: wet-blues


Washing: 200% Water at 35 ° C
0.2% formic acid (1:10)
Roll 10 minutes.
Drain bathroom.
Neutralized: 150% Water at 35 ° C
1% sodium formate (1:10)
1% sodium bicarbonate (1:20)
Roll 1 hour. Look pH. Drain bathroom.
Retanning: 150% Water at 40 ° C
2% anionic polymer retanning
Roll 40 minutes.
Mimosa 3%
3% synthetic phenolic retanning
Roll 45 minutes.
Drain the bath.
Dye: 150% Water at 50 ° C
0.5% Dye
Roll 20 minutes.
0.5% formic acid (1:10)
Roll 20 minutes.
0.5% Dye
Roll 20 minutes.
0.5% formic acid (1:10)
Roll 20 minutes.
Look pH.
Drain bathroom.

Practice 3: Dyeing sandwich with different load changers

Skins: wet-blues

Washing: 200% Water at 35 ° C
0.2% formic acid (1:10)
Roll 10 minutes.
Drain bathroom.
Neutralized: 150% Water at 35 ° C
1% sodium formate (1:10)
1% sodium bicarbonate (1:20)
Roll 1 hour. Look pH. Drain bathroom.
Retanning: 150% Water at 40 ° C
2% anionic polymer retanning
Roll 40 minutes.
Mimosa 3%
3% synthetic phenolic retanning
Roll 45 minutes.
Drain the bath.
Dye: 150% Water at 50 ° C
0.5% Dye
Roll 20 minutes.
1% aluminum sulfate
Roll 20 minutes.
0.5% Dye
Roll 20 minutes.
0.5% formic acid (1:10)
Roll 20 minutes.
Look pH.
Drain bathroom.

Practice 4: Tincture sandwich with different load changers

Skins: wet-blues

Washing: 200% Water at 35 ° C
0.2% formic acid (1:10)
Roll 10 minutes.
Drain bathroom.
Neutralized: 150% Water at 35 ° C
1% sodium formate (1:10)
1% sodium bicarbonate (1:20)
Roll 1 hour. Look pH. Drain bathroom.
Retanning: 150% Water at 40 ° C
2% anionic polymer retanning
Roll 40 minutes.
Mimosa 3%
3% synthetic phenolic retanning
Roll 45 minutes.
Drain the bath.
Dye: 150% Water at 50 ° C
0.5% Dye
Roll 20 minutes.
1% Oil cationic
Roll 45 minutes.
0.5% Dye
Roll 20 minutes.
0.5% formic acid (1:10)
Roll 20 minutes.
Look pH.
Drain bathroom

Practice 5: dyeing  sandwich with different load changers

Skins: wet-blues
% On shaved weight
Washing: 200% Water at 35 ° C
0.2% formic acid (1:10)
Roll 10 minutes.
Drain bathroom.
Neutralized: 150% Water at 35 ° C
1% sodium formate (1:10)
1% sodium bicarbonate (1:20)
Roll 1 hour. Look pH. Drain bathroom.
Retanning: 150% Water at 40 ° C
2% anionic polymer retanning
Roll 40 minutes.
Mimosa 3%
3% synthetic phenolic retanning
Roll 45 minutes.
Drain the bath.
Dye: 150% Water at 50 ° C
0.5% Dye
Roll 20 minutes.
0.3% formic acid
Roll 20 minutes.
1.5% Salt 33% chromium basicity
Roll 45 minutes.
0.5% Dye
Roll 20 minutes.
0.5% formic acid (1:10)
Roll 20 minutes.
Look pH. Drain bathroom.

Practice 6: Dyeing sandwich with different load changers

Skins: wet-blues
% On shaved weight
Washing: 200% Water at 35 ° C
0.2% formic acid (1:10)
Roll 10 minutes.
Drain bathroom.
Neutralized: 150% Water at 35 ° C
1% sodium formate (1:10)
1% sodium bicarbonate (1:20)
Roll 1 hour. Look pH. Drain bathroom.
Retanning: 150% Water at 40 ° C
2% anionic polymer retanning
Roll 40 minutes.
Mimosa 3%
3% synthetic phenolic retanning
Roll 45 minutes.
Drain the bath.
Dye: 150% Water at 50 ° C
0.5% Dye
Roll 20 minutes.
1% aluminum chloride
Roll 45 minutes.
0.5% Dye
Roll 20 minutes.
0.5% formic acid (1:10)
Roll 20 minutes.
Look pH. Drain bathroom.

Results and conclusion;

At the 1. dyeing practice we gave colorante one time and formic acid after it.At the 2. practice we gave colorante and formic acid with parties so we can see on the colour of the leather is beter darker we had beter results.at the 3. practice we used  aluminium sulfate we can see beter homogenity of dyeing and more intensity.at the 4. practice we used cationic oil so we can see leather has a softer touch silky feelingat the 5. Practice we used %33 chromium it increase cationic reactive points so intesity of dyeing be beter.conclucion:second one has more intensity than others 3th one has beter homegenity than others in addition it has more firm touch because of aluminium.4th one more intensity than 5th one and silkt touch beter softness.if we compare homogenity 2>3>1>5>4.intensity 2>4>1>3>5.so we can see dyeing with parties gives beter results and for to get different properties from the leather we can choose cationic oil or aluminium sulfate or chromium.

2. Dyes in Crust




Crust: name that is known to all chrome tanned skin dry, the plant or in combination, oily and treated mechanically unfinished.

Objectives: To see the difference between a dye on wet-blue and crust. Compare two dye systems: crossed and crossed and see how they influence different load changers on the intensity, hue, matching, affinity to the skin, penetrating power and the degree of fixation of the dye.

Operating Method: In a large piece of skin soaking crust is done. From here, is to compare different dyes, so that small pieces were cut 8 to make the 8 practices described below.

Load Changers to compare: formic acid, aluminum sulfate, aluminum sulfate with different combinations with formic acid, oil cationic chromium salt basicity and 33% aluminum chloride. All these products can act as load changers, and each provides different results in the same dye.

3.    Practice 1:Dyeing not crossed

Skins: crust of unknown origin


Soaking: 500% Water at 35 ° C
Moisture 0.5% (1:10)
Ride 30 minutes. Rest 12 h, rolling 15 min / hour.
Drain bathroom.
Dye: 400% Water at 60 ° C
1.5% Dye (1:20)
Roll 20 minutes.
1.5% formic acid
Roll 20 minutes.
1.5% Dye (1:20)
Roll 20 minutes.
1.5% formic acid (1:10).
Roll 20 minutes.
Look pH.
Drain bathroom.











Practice 2: Dyeing crossed

Skins: crust of unknown origin


Soaking: 500% Water at 40 ° C
Moisture 0.5% (1:10)
Ride 30 minutes. Rest 12 h, rolling 15 min / hour.
Drain bathroom.
Dye: 100% cold water
1% ammonia
Roll 15 minutes.
3% Dye
Roll 1 hour.
300% Water at 60 ° C
0.5% formic acid
Roll 15 minutes.
1% Oil cationic
Roll
1.5% Dye (1:20)
Ride 30 minutes.
1.5% formic acid (1:10)
Ride 30 minutes.
Look pH.
Drain bathroom.






Practice 3: Dye crossed

Skins: crust of unknown origin


Soaking: 500% Water at 40 ° C
Moisture 0.5% (1:10)
Ride 30 minutes. Rest 12 h, rolling 15 min / hour.
Drain bathroom.
Dye: 100% cold water
1% ammonia
Roll 15 minutes.
3% Dye
Roll 1 hour.
300% Water at 60 ° C
0.5% formic acid
Roll 15 minutes.
1.5% Salt 33% chromium basicity
Roll 45 minutes.
1.5% Dye (1:20)
Ride 30 minutes.
1.5% formic acid (1:10).
Ride 30 minutes.
Look pH.
Drain bathroom.

Practice 4: Dye crossed

Skins: crust of unknown origin


Soaking: 500% Water at 40 ° C
Moisture 0.5% (1:10)
Ride 30 minutes. Rest 12 h, rolling 15 min / hour.
Drain bathroom.
Dye: 100% cold water
1% ammonia
Roll 15 minutes.
3% Dye
Roll 1 hour.
300% Water at 60 ° C
0.5% formic acid
Roll 15 minutes.
1% aluminum sulfate
Roll 45 minutes.
1.5% Dye (1:20)
Ride 30 minutes.
1.5% formic acid (1:10)
Ride 30 minutes.
Look pH.
Drain bathroom.






Practice 5: Dye crossed

Skins: crust of unknown origin


Soaking: 500% Water at 40 ° C
Moisture 0.5% (1:10)
Ride 30 minutes. Rest 12 h, rolling 15 min / hour.
Drain bathroom.
Dye: 100% cold water
1% ammonia
Roll 15 minutes.
3% Dye
Roll 1 hour.
300% Water at 60 ° C
0.5% formic acid
Roll 15 minutes.
1% aluminum chloride
Roll 45 minutes.
1.5% Dye (1:20)
Ride 30 minutes.
1.5% formic acid (1:10)
Ride 30 minutes.
Look pH.
Drain bathroom.

Results and conclusion;

Most firm one is 5th one cause of aluminium clorur effect.if we compare firmness of leathers 5>4>2>1>3 if we compare intensity of colour we can see 5>2>1>3>4.we see again effect of aluminium as firmness more.And chromium is more soft and brighter.and cationic oil has more silky feeling.we can choose the load changer we want from leather properties.but i think aluminium clorur gave the best results in our practice homogenity,intensity and hue characteristics.Normally aliminium clorur is less effective than aliminium sulfate.aluminium sulfate gives more bright hues.

3. Vegetable dyes in Tanning



Vegetable tanning: a vegetable tanned leather differs from a chrome-tanned for several characteristics that influence how you make the dyeing: lower temperature results in a contraction, so it should work with lower temperatures. The vegetable tanned leather has a distinctive color ranges from brown to yellowish brown to reddish brown that strongly influences the final color of the dye. The vegetable tanned leather has a global anionic charge while the chrome-tanned leather has a cationic overall charge. Therefore the type of dyes used may be different, or at least the skin must be prepared differently.

Objectives: To see the differences between a set of chrome dye skins and furs to the plant. Compare two dye systems: crossed and crossed and watch changers charge different influence on the intensity, hue, matching, affinity to the skin, penetrating power and the degree of fixation of the dye.

Operating Method: In a large piece of vegetable tanned leather takes a soaking.From here, is to compare different dyes, for it is cut into small pieces 4, 4 to perform the practices described below.

Practice 1: Dyeing surface

Skins: vegetable tanned

Soaking: 1000% Water at 30 ° C
0.1% nonionic wetting (1:10)
Roll 10 minutes. Stand 8 hours, rolling 5 min / hour.
Drain bathroom.
Tincture: 1000% Water at 45 ° C
2.5% Dye
Roll 20 minutes.
20% Water at 60 ° C
Ride 30 minutes.
1.5% formic acid (1:10)
Roll 20 minutes.
Look pH.
Drain bathroom.


Practice 2: Dyeing crossed

Skins: vegetable tanned


Soaking: 1000% Water at 30 ° C
0.1% nonionic wetting (1:10)
Roll 10 minutes. Stand 8 hours, rolling 5 min / hour.
Drain bathroom.
Dye: 300% Water at 30 ° C
5% Dye
Roll 1 hour.
500% water at 45 ° C
Roll 10 minutes.
1% formic acid (1:10)
Roll 15 minutes.
Oil 2.5% cationic
Roll 15 minutes.
2% direct dyestuff
Ride 30 minutes.
1.5% formic acid (1:10)
Ride 30 minutes.
Look pH.
Drain bathroom.

Practice 3: Dye crossed

Skins: vegetable tanned


Soaking: 1000% Water at 30 ° C
Moisture 0.1% (1:10)
Roll 10 minutes. Stand 8 hours, rolling 5 min / hour.
Drain bathroom.
Dye: 300% Water at 30 ° C
5% Dye
Roll 1 hour.
500% water at 45 ° C
Roll 10 minutes.
1% formic acid (1:10)
Roll 15 minutes.
Aluminium sulphate 2.5%
Roll 15 minutes.
2% surface coloring
Ride 30 minutes.
1.5% formic acid (1:10)
Ride 30 minutes.
Look pH.
Drain bathroom.







Practice 4: Dye crossed

Skins: vegetable tanned


Soaking: 1000% Water at 30 ° C
Moisture 0.1% (1:10)
Roll 10 minutes. Stand 8 hours, rolling 5 min / hour.
Drain bathroom.
Dye: 300% Water at 30 ° C
5% Dye
Roll 1 hour.
500% water at 45 ° C
Roll 10 minutes.
1% formic acid (1:10)
Roll 15 minutes.
Aluminum Chloride 2.5%
Roll 15 minutes.
2% surface coloring
Ride 30 minutes.
1.5% formic acid (1:10)
Ride 30 minutes.
Look pH.
Drain bathroom.




Results and conclusion;

1th practice of leather doesnt have homogenity and intensity not a good example.the other ones we can see beter effects.in the second one deeper colour and softer structure we can see,dark and homogenius view we can see.if we compare intensity 2>3>4>1.if we compare brightness 1>4>3>2.only 1th practice we didnt use direct dyestuff we have good covering,fixing dye mistakes,full penetration and intensive colour effect in fibrils.so using direct dyestuuf is can be a good idea for vegetable leathers and firmness intensity and hue we can choose different load changers as the result of the leather good we want.

Final  comparetion and conclusion;

We always see the different effects of load changers.Vegetable leathers gives darker hues than other ones,and more homogenity cause of using direct dyestuff.and we can see less damage and more homogenity in the wet-blue leathers.we have darker and deeper colours and silky effect with cationic oil.sulfate aluminium gives more brightness itsmore effective than aluminium clorur.and we can see more firmness with aluminium clorur.and chromium give lighter colours than others more softness as usual.we use always formic acid it reduces pH below the pI value of the leather,so that the overall charge is cationic and has a greater capacity of reacting with anionic products subsequently added.its sometime decrease the basicity if given after more basic product that helps to not too bad and faster effect.

REPORT OF DYEİNG PRACTİCES

BY;EGEMEN C. AKTAS