Oil-drop dyeing spots
Appearance: Mostly occurring in T/R blended fabrics, there are oil droplet-like spots after dyeing, which are slightly darker than the normal parts. Observation by magnifying glass, in the fabric thick colour parts of the lint, the tip presents tiny bead shape, and more than the normal parts of the lint.
Cause: This is due to the uneven burning of the hair, dyeing spot thick colour parts, lint can not be fully burned away, in the tip of the fusion group, stronger colour absorption, so the dyeing is thicker.
Soak through spots
Appearance: The surface of the dyed fabric shows shades of colourful clouds.
Causes:
1). The receding pulp, the fine pulp is not sufficient, or the waxy material taken off by the treatment, etc., adheres to the fabric again.
2). The bath ratio is too small when bath dyeing, the heating rate is too fast, so that the dyeing solution is gelatinised.
Bleached Hole
Appearance: After bleaching with hydrogen peroxide, the fabric surface is broken by the warp or weft yarns and small holes are formed.
Cause: Rust is stuck on the fabric surface, or the water used in the bleaching bath contains iron ions, which cause the yarn to break during the bleaching process with hydrogen peroxide.
Skilteriness
Appearance: Irregular shades of colour on the fabric.
Causes: The desizing and refining of the pre-treatment process is not complete.
Mist
Appearance: Patchy stained spots, dark or light, inconspicuous in outline, varying in shape and size, occurring in different locations, and without certain rules.
Causes:
1). The fabric to be dyed is splashed with sewage or other drugs.
2). The fabric is not dried immediately after the practice bleaching, and it is piled up on the cloth cart for a long time, and some of the fabrics have air-dried water marks.
3). The embryo cloth is stained with oil, and the embryo inspection is carried out with a strong stain remover to remove the residual marks.
Colour difference
Appearance: Dyed or printed fabric, the colour of the finished product, or the colour of the printed pattern, is not exactly the same as that specified.
Causes: 1). The sample used for the specified colour sample is too small, so that the colour match cannot be made exactly the same after proofing. 2). Inaccurate weighing of dyestuffs and auxiliaries in the preparation of dyeing liquids or printing pastes. 3). The process is not fully compatible with the proofing conditions and no empirical corrections have been made.
Colour difference between cylinder
Appearance: Large batches of fabric, dyed several times in one or several cylinders, not in the same cylinder, with differences in colour and shade.
Causes: Although each vat is of the same type, its function may differ slightly. In the dyeing process, the conditions are not always the same from one operation to another.
Front and Back color difference
Appearance: Dyed full-width fabric with colour differences between the front and back sides.
Causes:
1). Pressure dyeing roller out of the edge of the fabric, the direction of travel of the fabric is not in the same plane with the pressure absorption line.
2). Press dyeing after pre-drying when the two sides of the fabric are subjected to different heat.
3). Different wind speeds on both sides of the fabric during resin processing.
Colour difference between left and right
Appearance: The full width of the fabric becomes progressively darker or lighter from the left edge to the right edge. When the two edges are folded together and compared, there is a significant difference in colour.
Causes:
1). The pressure-absorption rate of the dyeing machine rollers gradually becomes larger or smaller from left to right.
2). Poor engraving or production of the printing cylinder rollers or rollers.
3). Unequal pressure on the left and right side of the printing cylinder rollers or rollers.
4). Differences in temperature or air speed between the left and right side of the box during pre-drying, colour fixing or resin processing.
Medium thin, medium thick (Listing)
Appearance: There is a difference between the colour of the fabric near the edge and near the central part of the fabric, in shades.
Causes:
1). In the open-width interwinding dyeing machine, the curvature of the fabric expansion device is not suitable, so that the fabric does not absorb the dyeing solution at the same rate. The temperature in the dye bath is not uniform at both ends and in the centre. Uneven addition of new dyeing liquor.
2). In liquid flow dyeing machines, the fabric circulates at a slower rate, while the rate of temperature rise is faster.
3). In open-width continuous dyeing machines, inconsistencies between the central and the two ends of the rollers. The drying temperature and air speed are not uniform at both ends and in the centre. During continuous dyeing, the tension on the fabric body is not uniform.
4). Inconsistency between the centre and the sides of the fabric already formed during the pre-treatment process.
5). Uneven pressure between the centre and the ends of the fabric during rosette or rosette printing.
6). Dyeing is not followed by resin processing, or the resin is not completely dried afterwards, resulting in a long-lasting build-up.
Tailing of Ending
Appearance: A group of several or dozens of fabrics dyed continuously under the same set conditions, with a difference in shade between the beginning and end of the dyed fabric.
Causes:
1). In the pre-treatment process, a batch of fabric occurs before and after the difference of desizing, refining, bleaching, mercerising, shaping, etc.
2). When dyeing in open rolls, inconsistent dyeing rate using a combination of dyestuffs, inappropriate fabric guide and roll method, wrong dye addition, improper dyeing temperature control, all will cause the first and last colour difference.
3). During continuous dyeing, changes in the pressure absorption rate, poor stability of the dyeing solution and gradual changes in the drying temperature.
4). If the dyestuff and the auxiliaries used together are not compatible, an uneven layer of dyestuff particles and water may occur. Due to capillary action, water enters the fibres first, resulting in a change in the concentration of the dyeing solution, causing a difference in the first and last colours.
5). When dyeing with ice dyes, the dyestuff will gradually hydrolyse during the long immersion dyeing process, which will also cause the first and last colour difference.
Migration
Appearance: When the dyed fabric is dried, the water contained in the fabric evaporates and the dye moves with the water to the surface of the fabric, resulting in a change in the intensity of the shade on the surface of the fabric.
Causes:
1). The pressure absorption rate set during press dyeing is too large.
2). Excessive dyestuff used when mixing the dyeing solution, i.e. the concentration of the dyeing solution is too high.
3). Dyeing and drying for too long.
4). The drying rate is too fast.
5). No or insufficient amount of migration inhibitor added.
Warp Stripe (YarnTexture Streak)
Appearance: A rainfall-like streak in the direction of the warp yarn on the surface of a dyed woven fabric. In severe cases, this can also be seen on the fabric side of the cloth. Depending on the light and darkness of the inspection site, the direction of observation and the distance from the fabric, there may be significant or insignificant differences in the appearance of this defect.
Causes:
1). Differences in the count, evenness, twist and cross-sectional shape of the yarn used for weaving.
2). Improper choice of dyestuff, especially in the case of green dyeing.
3). If the polyester fabric is processed, it is improperly desizing before dyeing and there is a local residue of paste, which is less colourful and lighter when dyeing and shows warp stripes.
Barry Dyeing (Filling Band in Shade)
Appearance: In the weft direction of woven fabrics, or in the transverse direction of circular knitted fabrics, the colour of the dyed band is darker or lighter.
Causae.
1). The woven fabric has a dense or thinning defect.
2). Knitted fabric with uneven yarn tension or uneven number of terry loops.
3). Weaving with the same specification but with different lot numbers of filamentary chemical yarns.
4). Uneven heating of the chemical fibre yarn for knitting.
Fuel Spot (Dye Spot)
Appearance.
1). On the surface of medium and light coloured fabrics, there are tiny spots of the same colour.
2). Causes: 1). Causes.
1). Poorly dissolved dyestuff, with tiny particles remaining undissolved.
2). The dyestuff has flown during transport and has fallen on the fabric to be processed.
3). When the machine is not cleaned and the light colour is processed after the dark colour has been processed.
Rope Mark
Appearance: The fabric shrinks into a rope-like shape during rope dyeing, and after dyeing there are irregular wrinkles in shades of colour along the length of the fabric.
Causes: When dyeing with Winky or liquid flow dyeing machines, the fabric is not pre-formed or under-formed. Failure of the rolling bar to stop in the middle of dyeing. Rapid temperature increase or decrease. Dyeing bath ratio too small. Knotting of the fabric in the vat, etc.
Padding Mark
Appearance: When the woven fabric is pressed and dyed, the fabric is folded in the warp direction between the two rollers, and the pressure absorption rate varies due to the difference in thickness when passing through the pressure line. The folded part is slightly lighter in colour than the normal one. Most occur in a fabric of two cloth head part.
Causae.
1). The fabric to be pressed and dyed has already produced creases during the pre-treatment process, which cannot be completely eliminated when shaping.
2). The fabric expander of the press dyeing machine is not working, and the fabric is not opened up.
3). The seam between the pile and pile is not good, there are wrinkles or untidy phenomenon.
Uneven Dyeing on Selvage
Appearance: After dyeing the fabric, the selvage has a different shade from the fabric surface.
Causae.
1). The selvage of the fabric is too loose or too tight.
2). When shaping the fabric before dyeing, the edge of the fabric is held by a high temperature splint.
3). Curling of the fabric edge during dyeing.
4). When dyeing in open rolls, the fabric is not rolled up properly and oxidation occurs at the edge.
5). Insufficient reduction when dyeing with open-width interwinding sulphur or urn dyes.
6). Inconsistency in the rate of pressure absorption between the edge of the cloth and the surface of the cloth during open width press dyeing.
7). Insufficient washing after dyeing, residual drugs on the edge of the cloth.
Fading of Selvage or Discoloration
Appearance: After printing and dyeing, the finished fabric has a different shade of colour than normal.
Causes:
1). When processing resin, the temperature of the needle plate or splint is too high and the dye sublimates and escapes.
2). When using the rotary cylinder dryer to dry the fabric, the temperature is too high and the fabric edge is too tight around the fabric cylinder.
Edge Mark
Appearance: A cylindrical knitted fabric with abnormal dyeing on both sides of the cylindrical flat fold.
Causes:
1). Deterioration of the oil added during weaving.
2). Improper storage or long storage of the fabric, the edge of the fabric is affected by air and sunlight and becomes contaminated.
3). The temperature of the sizing frame is too high when the cylinder is being sized.
Cylinder contamination
Appearance: During the dyeing and finishing process, when the cloth passes through the cylindrical device, it is contaminated on the surface of the cloth due to uncleanliness of the circumference of the cylinder, such as sticky oil, chemicals, dyestuff and other filth. The shape is mostly in small pieces and there is a certain distance between the two contaminated areas.
Causes:
1). Oil stains on the fabric guide roller.
2). The press rollers are sticky with tar-like colour deposits, or dirt such as short fibres falling off from the fabric.
3). The drying cylinder is sticky with oil and dirt.
Dyeing Stop Mark
Appearance: Along the weft direction of the fabric or transversely, there is a trace from 2 to 10 cm wide, darker or lighter than the normal colour, and the two sides have a watermark-like shape.
Cause: When the machine stops running suddenly during normal operation due to power failure, fabric rolls or other mechanical faults, the fabric is held between the two rolls and occurs when the dyeing solution is pressed and absorbed or when the reducing solution is pressed and absorbed.
Colour spots
Appearance: The finished fabric has been packaged, after opening the fabric surface has darker spots of the same colour.
Cause: After dyeing and finishing the fabric, with sealed packaging, due to the condensation of evaporating water vapour, the dyes and processing agents with weaker wet fastness will cause them to move and form spot-like stains.
Printed crease
Appearance: On the surface of the printed fabric, there is an unprinted pattern along the warp or longitudinal direction in the shape of a shuttle or a long strip.
Causes: When printing, the fabric surface folds and overlaps, and the covered area is not printed with the pattern.
Printed pulp tube contamination
Appearance: The fabric printed on a white background is contaminated with a very small amount of printing paste in a very uniform way, mostly in the fabric of lollarisation.
Causes: 1). The mirror degree of the printing roller is not enough, easy to adhere to the printing pulp. 2). Scraper and printing cylinder contact is poor, or scraper is not often resharpened, not sharp enough. Printing on a white background Black or darker colours with larger patterns are most likely to occur.
