Testing dyed materials

Dissolve 10 mg of Congo Red in 40 mL of water, add about 0.1 mL each of 10% solutions of sodium carbonate and sodium sulfate, heat to a temperature just below the boiling point, and introduce a piece of test fabric. At the end of 10 min remove the fabric and wash in warm water as long as the dye is removed. Place pieces of the dyed material in very dilute hydrochloric acid solution and observe the result. Rinse and wash the material with soap. 

If a dyed material is under test, the stripping of dye will be necessary before the test can be carried out. Alternatively, degradation can be determined by titration using an anionic dye which precipitates Methylene Blue from solution. 

The strike-levelling test is designed to determine the rate of strike and the ability of partly dyed material to level. A liquor containing the dye under examination is made up so that it shall yield a shade equivalent in depth to one of the following. 

Phis test is intended to assess the resistance of dyed materials to concentrations of active chlorine, similar to those which may be present in swimming baths. A solution containing 20 mg of active chlorine per litre is prepared by first diluting 13 3 ml of sodiunj hypochlorite, containing 150 g per litre of active chlorine, to 1000 ml with distilled water, and then adding 10 ml of this to 1000 ml of a solution buffered to 8-5 with 51 ml of 0-1M sodium hydroxide solution l 0-0144 g of potassium chloride >per litre. 

The dyed material is sewn between two pieces of doth of the same fibre. The test solution contains 1 g of sodium chlorite (80 per cent) per litre and, before the test, sufficient acetic acid is added to bring the pH to 3 5. The specimen is wetted out in the solution and subsequently immersed in it at 80 2°C (176 4 F) for 1 hour, using a liquor ratioof 50 1. The sample is then washed in cold running water for 10 minutes and dried at a temperature below 60 C (140 F). 

The purpose is to test yams intended for use with wool, and which should withstand dyeing by all the methods that may be used for the protein fibre. The yams should be knitted into fabrics for the preparation of the samples. A pieee of the dyed material measuring 10 cmx 4 cm is placed between two pieees of undyed cloth and sewn round the edges. One undyed pieee should be of the same fibre as that of the sample undergoing test, and the other seleeted as follows ... 

Filtered-Particle Inspection. Solids containing extensive inteiconnected porosity, eg, sintered metallic or fired ceramic bodies formed of particles that ate typically of 0.15-mm (100-mesh) screen size, are not inspectable by normal Hquid penetrant methods. The preferred test medium consists of a suspension of dyed soHd particles, which may be contained in a Hquid vehicle dyed with a different color. Test indications can form wherever suspensions can enter cracks and other discontinuities open to the surface and be absorbed in porous material along interior crack walls. The soHd particles that form test indications ate removed by filtration along the line of the crack at the surface where they form color or fluorescent indications visible under near-ultraviolet light (1,3). 

The soil used in the experiment was a low plasticity sandy material with a PI of about 11%. The variations in hydraulic conductivity probably reflected zones of material that contained more sand in some places and more clay in others. Tests have been performed on a couple of liners in the field where liquid flowing into the soil liners has been dyed and traced by cutting a cross section or trench through the liner. The result seems to indicate that dyed liquid finds a defect in the top lift, moves down and spreads along a more permeable zone between lifts finds another defect, moves downward, spreads finds another defect and so forth. 

Technical Tests.—To ascertain the suitability of a starch for use in the dressing of textiles, samples of fabrics dyed with sensitive colours (benzopurpurin, Turkey red, logwood black) or of bleached fabrics are treated with the starch the dry materials are examined as regards feel and change of colour, while the general appearance is compared with that of the same material dressed with a standard starch. 

For the dyeing test it is hence necessary to vary the procedure in accordance with the fibre to be dyed and the colour desired. In general, comparative tests are made with a standard alizarin and that under examination, using strips of cotton material (calico) mordanted in different ways, namely ... 

With dyed linen, hemp, ramie and jute materials, there are no such precise standards of fastness as for cotton. In general, however, linen, hemp and ramie products are examined, in the manner described above, by most of the tests indicated for cotton materials. Goods made of jute arc usually only tested to ascertain if they withstand the action of water without losing their colour. 

Production tests on the textile material to be dyed fastness testing. 

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