Friday, February 25, 2011

CHEMICAL ANALYSIS OF WATER:

             An industrial laboratory should not in general attempt to analyse water for drinking purposes. Th egardness having been determined together with other data necessary for steam raising purposes the only other data required are suspended matter humic matter iron dissolved oxygen and in rare cases sulphuretted hydrogen.

            Suspended matter.Filter I Liter though tared filter papers dry at mon more than one hundred and five deg .C. and weigh .In natural waters the residue may contain fine sand or earthy matter. In softened waters there may be suspended calcium and magnesium salts which sometimes continue to percipitate for some hours after softening. In zeolite especially from certain friable types .  There may also be iron rust from water pipes and suspended humic matter from moorland waters .  Occasionally filamentous algae are present. Suspended matter is very objectionable in all syeing processes where the dyeing liquor is circulated through packages of fibrous material whether hank cake top or beam.  Humic acid is a nuisance in neutral dyeing as it is absorbed by animal fibres almost like a neutral dyeing buff coloured dye stuff. In one case when water contained much humic matter pale blues could be obtained only by dyeing some material intended for dark shades in the water to be used for the blue shade to remove the hmic matter.  Iron is responsible for the flattening of shades with iron sensitive dye stuffs.

Iron .
         The I Liter of wather from determination of suspended matter is evaporated to dryness. Add dilute hydrochloric acid evaporate to dryness ignite moisten with conc.  HCI stand fifteen minutes add water boil filter through iron free paper and determine by any the usual colorimetric methods.  The residue from filtration is ignited and treated in the above manner.

Microscopical Ecamination :
         Some information usually more interesting than useful can be given in Wallis Analytical Microscopy or the standard work by thorpe and others may be consulted.
FILAMENT FIBRES:
         IN This pure silk is grouped with all those artificial fibres which have as a common property a single filament formation which is structureless in comparison with the natural fibres.
TURE SILK :
           
      This is a protein fibre and may be regarded chemically as a simplification of the wool protein ,the fundamental protein is a long chain molecule in which the unit NH CH CO is repeated many times. The protein is based principally on glycine and alanine residues with some tyrosine but cystine is absent and there are no cross linkages of sulphur as in wool all the cross links are salt linkages.
      Structurlly sill is uniqe amongst natural fibres in that it dose not deem to have any surface dkin or cuticle unless indeed dilk gum itself is regarded as a kind of cuticle layer.  Silk is perhaps the least complicated both chemically and physically of the natural fibres.
     It is produced by the larva of the bombyx mori moth which extrudes the filament from twin spinnerets when making its cocoon .  The filament proper consisting of the protein fibre is coated with an alkali soluble variant of fibroin termed serecin .  In the undegummed state silk appears as twin filaments which are more or less stuck together by serecin .
      In the process of reeling the silk filament from the cocoon the outer and inner layers are discarded as waste.  These layers are characterised by irregularity in diameter and especially by irregularity in the thickness of the serecin layer.  Waste silk is also provided by pierced double or feeble cocoons and by damaged cocoons.  There are several recognised qualities of silk waste. In the working up of waste the silk is degummed and carded which tears it p into short lengths of a staple corresponding roughly with the range of wool staples the carded silk is then combed on principles not dissimilar to those used in wool combing various staple lengths or drafts being produced which are spun into yarns of a fineness corresponding to the draft. such yarns are generally known as schappe and are manufactured into pile fabrics or spun silk goods. They have their analogy in viscose staple fibre . Schappe silk is often only partly boiled off.

EFFLUENTS :

The detailed treatment of effluents is outside the scope of this book but it may be said that very few effluents from texitle works are fit to be turned into a river shilst certain types such as alkaline wool scouring liquors will not be accepted by many sewage works without prior treatment. In the normal treatment of sewage it is necessary to have a fairly neutral liquid . It is an advantage for a textile laboratory to have some understanding of the prooblem of the sewage chemist . A general reviw written from the textile laboratory point of view is given in garner industrial microscopy . The textile laboratory may be concerned in oxidising sulphide effluents or arranging that mutually reacting effluents sulphide and acid effluents do not enter the same drain or in previnting the unpleasant smell from some biological retting a drip feed of potassium permanganate into the drain . The most important problem likely to be encountered is in connection with wool sxouring effluents. Here the works is faced either with payment of a certain sum to the local corporation for the acid treatment of the effluent or with the acid treatment of the effluent in the works.




Wednesday, February 16, 2011

METHODS OF COLOR MEASUREMENT

COLOR MEASUREMENT:

                          It is often desirable to record the exact color of dyed material or yarn for future reference or for transmission by cable radio or letter to some distant person or for comparison with some other specimen of dyed goods, or for the purpose of making a quantitative estimation of the change in shade brought about by exposure to light or by testing for fastness to washing which cannot be made by mere visual observation.

         Of the recording methods in use some are of direct practical interest to dyers whilst other are more suited for the scientific laboratory.Of the former type are the British color council 's dictionary of standards the Ostwald color chart the love bond   Tintometer and the Toussaint colorimeter . Belonging to the second group are the Guild trichromatic colorimeter the nutting colorimeter and the Donaldson .

         All these instruments have their special uses in the recording and interpretation of color and of color changes . There is no universal methods of color measurement which can by applied to any problem and the methods to be used for the measurement of color in any particular  instance must be decided by practical considerations.

Tuesday, February 15, 2011

TESTS FOR MIXTURES

                                            MIXTURES TESTS

       Of further tests the tirst should be to determine if the dye stuff is a mixture .A large number of commercial dye stuffs are mixtures but a competent dye house will find few of them worth buying ; the value test previously given will eliminate most of them .It is a good general rule never to buy a mixture  though dye manufacturer has after much experiment found a blend of two or which exhausts on tone in jigger or warp dyeing and such blends if tinctorially of good value are useful.In most cases however a skilled dyer will produce results as good as those given by the mixture and more cheaply with individual dye stuffs whose properties he knows precisely and which are normally kept in the dye stores.


       Dye stuff mixtures are usually prepared by blending powders and only very occasionally by salting out a mixed solution .Therefore if a small amount is picked up on the end of a spatula and blown on to a piece of wet filter paper or in some cases on to cons . Sulphuic acid in a watch glass the individual specks become separated in space and dissolved separately according to their color . It is often possible to make a rough estimate of the number of dye stuffs their proportions and colors . A small percentage of one color additional to the main dye stuff may be permitted as a legitimate addition for shade standardization whilst many dye stuffs connote be made without the presence of homologues etc.
        The average size of the molecular aggregates in a dye stuff solution varies very considerably from one dye stuff to another and as the aggregate size determines the speed at which the dye stuff passes through the pores of filter paper it is useful to put a drop of solution on to some thick filter paper and observe the way the frop spreads. A mixture usually shows rings of color the more soluble and less aggregated dye stuff travelling farther and more rapidly than the rest.

        Sharper separation may sometimes be obtained by putting the drop adjacent to a previously applied drop of strong salt solution .


       This test may be modified by hanging an inch wide strip of filter paper then (10) ins. long vertically over a dish of dye stuff solution with the lower end just dipping into the liquid. After perhaps ten minutes there will be distinct separation into zones . A mixture in which the colored zones are close together is in general likely to be better balanced as regards rate of exhaustion on dyeing than a mixture in which the zones are widely separated.Dye stuffs that contain such diluent as dextrin will climb hardly at all nor will very aggregated dye stuffs of the quick exhausting bad leveling type . Roughly speaking dye stuffs that climb to (80%)or more of the height of their solution water are good leveling acid colors a climb of (70%)indicates a neutral wool color and less than (40%)indicates a direct cotton color . There is however some overlap and some colors greatly aggregated in cold solution are well dispersed in a boiling dye bath. The capillary strip method may be used to examine the effect of salt and acid additions. Often in a mixture the addition of a suitable amount of salt will repress the climb of one component completely.


       The method may be extended into a chromatographic analysis but this is not suitable for routine examination and moreover there is little published work on dye stuffs . It is however now clear that complete and clean separations of the component dye stuffs in a mixture and also of impurities present may be accomplished in many cases be choice of an adsorbent of suitable particle size and chemical affinity coupled with a suitable elutriant.

      Other methods of examination for mixtures are 1 dyeing six hanks with zero one two four eight and (16%)of salt 2 preparing a boiling dye bath and dyeing six hanks successively for one minute each 3 dyeing one hank at fifty six to sixty deg. C. for a quarter of an hour and then exhausting the bath by dyeing with a second hank followed by dyeing at seventy deg. C.with a cotton hank . In all these cases changes in hue indicate mixtures.





Sunday, February 13, 2011

RECOVERED WOOL

SHODDY:

               Is wool recovered from long staple yarns such as stockings and knitwear. Mango is wool recovered from short staple yarns woolen and milled goods. Extract or alpaca is recovered from rags by carbonizing.
               Examination o recovered wool fibers should be stripped with hydrochloric acid to remove dyestuff used in redyeing before examination of initially dark fibers . Usually there is a mixture of fibers of various colors
possibly some non wool fibers will be present . The ends of the fibers are usually torn or rigged and brush like due to mechanical and chemical treatment .Mechanical damage is well demonstrated by staining with kit-on Red G. Scales may be broken or absent . The diameter may be irregular and fibers will bend sharply instead of curving gradually . The absence of scales alone on a few fibers does not indicate a proportion of shoddy in an otherwise apparently sound sample of wool as tip wools have no scales.


                                                        UNCOMMON FIBERS

CAT:
       Staple .
                  One to two cms ends regular pointed diameter fourteen to thirty four microns  medulla is a single series of regular cells zero miner five zero miner six micron diameter.
       Horse.
                  Generally long hairs from the mane and tail white or black very long staple showing a strong characteristic medulla frequently in commerce artificially curled by steam diameter nineteen to two hundred and fifty microns. Also short hairs one to two cms long and eighteen to hundred microns diameter are sold as horsehair . Colored horsehair is pigmented throughout its cross section dyed adulterants in cross section usually show a dark exterior and a pale interior( dyed cow-tail) .
       Musk ox.
                    Fibers two and four point and one half ins.long diameter thirteen to twenty five microns in general similar to camel hair medulla mostly absent
      Musk rat.
                    Similar to rabbit but medulla cells mostly empty .
                 

Saturday, February 12, 2011

EVALUATION AND ANALYSIS OF DYE STUFFS

FROM
            The present standpoint dye stuffs fall into the following groups.

Basic Dye stuffs
                
            These are organic bases of certain types containing free amino groups . They form salts with acids such as hydrochloric or oxalic acids , and double salts with certain metals such as zinc. For dyeing they are supplied in one or other of the above forms either pure or diluted with an inert body such as Dexedrine . For the coloring of
oils they are supplied as the free base . They dye silk ,wool,jute,and nylon from neutral ,slightly acid or soap containing baths .
            They do not dye cotton itself but as they form insoluble compounds with tannins and tannins are absorbed strongly by cotton with tannin .To obtain improved results the tannin may before dyeing be converted on the fibre into the insoluble antimony salt. They also form precipitates with many acid and direct cotton dyes and can therefore not be used in the same bath with such colors.  As a class they give very bright shades but that is almost their only virtue and they are rapidly dropping out of use.

True Mordant Dye stuffs
        
              These dye stuffs do not dye wool at all well alone but combine with chromium aluminium and iron to form lakes .The will therefore dye wool which has previously been treated with a salt of one of these metals.
They are often exceptionally fast but usually dull in shade . As their affinity is for the metallic mordant and not for the fibre they will dye any fibre wool cotton silk viscose which can be induced to become mordanted with a suitable metallic salt.     

Friday, February 11, 2011

BIOLOGICAL METHODS


BIOLOGICAL METHODS



          This article is confined to the recognitionof the effects of biological activity during the processing storage or use of textile .The technique of microbiological work and the identification of bacteria fungi and insects is highly specialized and unsuitable for routine work in a textile laboratory.

INSECTS
      
          The major enemy to textile materials in this country is the moth grub in other countries certain beetle grubs cause much damage both to textile fibres and to starchy materials mites which are not ture insects cause damage to flour and may give rise to so called dermatitis in operatives.

 MOTHS
      
          Moths themselves gave atrophied mouth parts and cannot eat it is the grub that causes damage to textile materials. Tineola Bestselling the clothes moth produces a grub which forms a silky tunnel as it moves
about and spins a silky cocoon whin fully developed . Tina pellionella the fur moth produces a grab which builds round itself a case of silk covered with small bits of fibre which is dragged along by the grub as
it moves about .Tricopbage tapietella (the tapestry moth )produces a grub which makes neither tunnel nor case but burrows in th material lining the burrows with silk .The grubs live on keratin like bodies and only cat vegetable matter when there is nothing else to eat but cannot digest it .  The majority of moths seen flying even inside the house especially in the country are not clothes moths and their grubs do no harm to textiles.
      
         Certin chemicals such as naphthalene and paradichlorbenzene are distasteful to moths and are avoided by them in sufficient concentration (but a concentration which cannot be realized in textile ware houses) these
 bodies are faral to moths . in most instances such chemicals are not fatal tithe grubs . Infected material may be sterilized by steam or fumigation by mixtures of ethylene oxide and carbon monoxide in suitable cases.

Thursday, February 10, 2011

The Toussaint Colorimeter

                                       TOUSSAINT COLORIMETER 

           This instrument works on quite a different system. in this case the pattern which is to be examined is illuminated by a strong strong standard white light. The light which is reflected from the pattern is collected by a lens and is passed through a color filter.Suppose this filter to be green and the pattern to be scarlet in color but the small amount of light which does pass through is directed on to the sensitive surface of a photo electric cell.
              The photo electric cell consists of a glass bulb which is filled with the inert GSA argon at low pressure . On one half of its inner surface there is a thin layer of potassium. Inside the bulb set at a small distance from the potassium there is a square of tungsten wire . The tungsten wire is connected to the negative . There is this an electric circuit consisting of the interval between the tungsten and the potassium.
              When a beam of light falls on the potassium this layer emits electrons which journey across the break in the circuit from the potassium layer to the tungsten wire thus causing the amount of current passing through the circuit to increase very considerably . The number of electrons emitted by the potassium is in exact proportion to the amount of light falling on it . If therefore Anny electrical measuring instrument such as a galvanometer is placed the circuit threading of the galvanometer shows the amount of light falling on the cell . The instrument therefore constitutes a very delicate and exact electric eye .The amounts of light passing through the red filter can be measured in terms of an electric current going through the circuit.  

Monday, February 7, 2011

LUMINESCENCE

           Luminescence is the general name gicen to the emission of light from a substance, adn ehich is producesd by some reaction other than burning. Chemical luminescence is consequent upon certain chemical reactions; an example is the glowing osf phosphorus in solution in olive oil. Thermoluminescence is excited by heating or cooling ; green fluorspar fragments thrown upon a hot surface shine brightly, whilst quinine gives off light on cooling from a high temperature.
          Frictional luminescence is shown by cane sugar adn by a few specimens of diamond   Crystallisation luminescence is shown by a 20% solution of arsenious oxide in boiling conc, HCI, which emits a flash as every crystal is formed . 
          From a textile point of view , fluorescence and phosphorescence are of most importance. Phosphorescent substances after having been exposed to light glow, and continue to glow, for some time after the light sourxe has been cut off; examples are luminous paint ( calcium sulphide ) and , at very low temperatures, ordinary paper . Fluorescence describes the emission of light of one wave-length when exposed to light of a different ( and usually shorter ) wave- length ; the fluorescence ceases immediately the light source is cut off , thus distingushing it from phosphorescence; an example is the yellowish green fluorescence of Rhodamine concurrently with the absorption of green light of a certain wave-lingth.

Saturday, February 5, 2011

BURSTING STRENGTH

               The machines used for this test tend to give a value which is the sum of the strength warp way and weft way. The test is particularly useful for knitted fabrics, which have no warp and weft and are extremely difficult to test by the usual fabric machines. It is also important for such fabrics as parachute silk, which in actual use are subjected to stresses of equal value both warp and weft way simultaneously. (see B.S.I. handbook No.11 (1949),P143.)
                 In one form of ball-bursting machine the fabric is clamped tightly between two annular rings, of 1.75-in .internal diameter , and a steel ball of 1-in .diameter is pressed down upon the fabric until it bursts under the pressure, which is then read , The main recommendation for this type of machine is that it can be designed to replace the jaws on an ordinary fabric testing machine. The ball burst strength in this type of machine is about 33% greater then the strip test strength of a woven fabric in the weaker direction .
                In the bydraulic burst tester a rubber dia phragm is placed over an annular ring , the fabric is placed upon the rubber diaphragm, a second annular ring is clamped down , and hydraulic pressure (using water or glycerine)  is exerted against the rubber diaphragm. The bursting strength is read on a pressure gauge at the point when rupture of either warp or weft direction occurs.  The machine has to be calibrated for the pressure required to stretch the rubber diaphragm.  In the mullen machine of this type the diameter of the cloth circle tested is 1.2 in , but it is advisable to use circles of much larger diameter in order to obtain a more average result, and to eliminate errors due to the lack of fibre slippage with circles of 1-2 ins. diameter . In all textile testing it is advisable to have the length of specimen tested as least as long as the mean fibre length in the specimen , and preferable of such a length that 90% of the fibres are held only at one end.