Sodium chloride concentration, penetration

The simplest way of dyeing a fiber is by a direct dye. The dye is dissolved in water so that its concentration is about 0.02 to 0.1 per cent. The amount of dye depends on the weight of the cloth. For light shades the amount of dye is 0.05-0.3 per cent, and for deep shades 4-10 per cent, of the weight of the cloth. A small amount of sulfated alcohol soap is added to reduce the surface tension of the solution and thereby aid in the penetration of the dye. Inorganic salts are added to the dye bath, such as sodium chloride for cotton dyes and sodium sulfate for wool dyes, in amounts varying from 5 to 10 per cent. The fiber is steeped in the dye bath and heated at 80-100° until the proper shade has been... 

The penetration or addition of chloride-bearing salts changes the chemical composition of the pore solution, depending also on the type of salt (i. e. sodium chloride or calcium chloride). This is due to chemical or physical binding of chloride and hydroxyl ions for instance, sodium chloride increases the OH concentration (and thus the pH), while calcium chloride decreases the pH [9]. 

From the table it will be seen that in case the concentration of NaR is large in comparison to that of NaCl the latter will scarcely penetrate the membrane. On the contrary, if the concentration of NaCl is very large compared to that of NaR, the latter will scarcely affect the diffusion of the sodium chloride. 

Alternatives to Sulfites. To meet the needs of the food industry for alternatives to sulfites, a number of browning inhibitor formulations have been marketed. These products are mostly combinations of AA, EA, or their sodium salts with such adjuncts as citric acid, sodium or calcium chloride, phosphates, cysteine and potassium sorbate (23-29). Commercial browning inhibitor formulations vary widely both in AA or EA content and in recommended use levels (Sapers, G. M., Eastern Regional Research Center, Philadelphia, PA, unpublished data). These sulfite substitutes are considered to be less effective than sulfites because they do not penetrate as well into the cellular matrix (11). Furthermore, AA is easily oxidized by endogenous enzymes (18) or by autoxidation, and in the course of its intended role as a browning inhibitor, may fall into a concentration range where it exerts pro-oxidant effects (30). To enhance their effectiveness, the sulfite substitutes may be used in conjunction with modified atmosphere or vacuum packaging (29,31). 

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