Acid-removable skin matrix acidizing

Acidic bathroom cleaners have some distinct advantages on common bathroom soils. First, the main matrix for the soil referred to as soap scum is soap that has been precipitated by water hardness ions. Imbedded in this matrix may be skin flakes, lint, dirt, etc. (see Figure 13.7), but the waxy precipitated soap serves to hold the mass together and make it adhere to surfaces. Acids can work to reverse this chemical reaction, turning some part of the soap fatty acids into liquid components (notably oleic acid). This serves to soften the soil overall and thereby make it more easily removed. Second, if there were any ion bridging of the soil to a receptive... 

Soap scum tends to be built up as fine layers of calcium or magnesium fatty acids on the bathroom surfaces, gradually dulling the surface and serving as a matrix for trapping other soils, such as sloughed skin cells, dirt, lint, and mildew. Many bathroom surfaces are fabricated to be shiny, and the soap scum, which is white or cream colored, tends to become apparent when the shine is dulled. As the more popular bathroom colors are pale or white, it is hard to see the soap scum itself on the surface, owing to the lack of color contrast. Soap scum is much more apparent on dark surfaces (like black ceramic tiles) or on transparent surfaces (like transparent shower doors). It is therefore somewhat hard for the consumer to determine that the soap scum has been completely removed from the surface except by the reappearance of the native shine of the surfaces. 

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