BACKGROUND: Hardness in water is consisted with mineral salts, including calcium (Ca(++)) and magnesium (Mg(++)). The mineral salts react with soap to form an insoluble precipitate known as metallic soap (soap scum). Since metallic soap remains tightly on the skin and is hard to rinse off, it may become one of irritants that exacerbate dermatitis. In this study, we used cation-exchange resin to prepare ultra-pure soft water (UPSW) excluding both Ca(++) and Mg(++), and investigated effect of UPSW rinsing on skin conditions in subjects with atopic dermatitis. Furthermore, antigenic activity of metallic soap was investigated by in vivo experiments. METHODS: Stratum corneum was collected from arms of healthy volunteers who rinsed soap in tap water or UPSW, and the quantity of remained soap scum was determined with a gas chromatography. After 4 weeks of bathing in UPSW, the water content of the stratum corneum and transepidermal water loss (TEWL) of volunteers with mild atopic dermatitis were measured. With atopic NC/Tnd mice, a model for atopic dermatitis, we attempted to confirm results obtained from atopic volunteers. Plasma total IgE was measured by an ELISA after immunization of mice with metallic soap. RESULTS: On skins rinsed in UPSW, soap was disappeared immediately and remained metallic soap was significantly reduced when compared to that on skins rinsed in tap water. In skins of atopic volunteers who used UPSW for bath, the water content in stratum corneum was increased

magnesium ions in hard water reacts with soap, forming insoluble stearates, commonly called soap scum or soap curd. The most common means for removing water hardness Water softening is the removal of calcium, magnesium, and a small number of other metal cations in hard water. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. Soft water also extends the lifetime of plumbing by reducing or eliminating scale build-up in pipes and fittings. Water softening is usually achieved using lime softe Water softening is the removal of calcium, magnesium, and a small number of other metal cations in hard water. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. Soft water also extends the lifetime of plumbing by reducing or eliminating scale build-up in pipes and fittings. Water softening is usually achieved using lime softening or ion-exchange resins, but is increasingly being accomplished using nanofiltration or reverse osmosis membranes. The presence of certain metal ions like calcium and magnesium, principally as bicarbonates, chlorides, and sulfates, in water causes a variety of problems. Hard water leads to the buildup of limescale, which can foul plumbing, and promote galvanic corrosion. In industrial scale water softening plants, the effluent flow from the re-generation process can precipitate scale that can interfere with sewage systems. The slippery feeling associated with washing in soft water is caused by the weaker attraction of the soap to the water ions when the water has been stripped of its mineral content. The surface of human skin has a light charge that the soap tends to bind with, requiring more effort and a greater volume of water to remove. Calcium and magnesium ions in hard water reacts with soap, forming insoluble stearates, commonly called soap scum or soap curd. Bac… Lime softening is the process in which lime is added to hard water to make it softer. It has several advantages over the ion-exchange method: silica, alkalinity… Chelators are used in chemical analysis, as water softeners, and are ingredients in many commercial products such as shampoos and food preservatives. Citric acid is used to soften water in soaps, personal care products and laundry detergents. A commonly used synthetic chelator is ethylenediaminetetraacetic acid (EDTA), which may exist as a tetrasodium or disodium salt. Due to environmental and aquatic toxicity concerns regarding widespread use of EDTA in household and personal care products, alternatives such as sodium phytate/phytic acid, tetrasodium glutamate diacetate and trisodium ethylenediamine disuccinate are finding more prevalent usage.

Soap scum can be removed by using an appropriate surfactant with a chelating agent. However, ethylenediaminetetraacetic acid (EDTA), one of the most widely used chelating agents has low biodegradability and is suspected to be toxic to aquatic life. The purpose of this research was to investigate an approach to dissolve different types of soap scum by using different surfactants with various biodegradable chelating agents. The solubilities of two soap scum (calcium stearate, Ca(C₁₈)₂ and magnesium stearate, Mg(C₁₈)₂) were investigated at various solution pHs (from 4 to 11) and different types of surfactants: methyl ester sulfonate (MES) as an anionic surfactant, alcohol ethoxylate with 9 ethylene oxide groups (EO9) as a nonionic surfactant, and dimethyldodecylamine oxice (DDAO) as an amphoteric surfactant in the presence of different biodegradable chelating agents: ethylenediaminedisuccinic acid (EDDS) and glutamatediacetic acid (GLDA). The highest equilibrium solubility of any soap scum was observed at a pH of 11 with DDAO and GLDA. In addition, the calcium soap scum system had higher equilibrium solubility than the magnesium soap scum system.