Acidification
Under acidification is understood:
In concrete construction
- Removal of limescale deposits , veils, efflorescence or impurities on concrete surfaces by using dilute acid solutions (e.g. hydrochloric acid ).
- Process for the production of exposed concrete surfaces: Dilute acid solutions are used to remove the top layer of cement stone and to obtain exposed aggregate concrete or sandstone-like surface structures (which can also be produced by sandblasting ).
- Measure to improve the adhesion of (alkali-sensitive) paints on highly calcareous surfaces
In metal construction
Pretreatment of galvanized surfaces (" zinc primer ") to improve the adhesion of paints and varnishes .
In textile technology / finishing
When completing neutralization (chemistry) of an alkaline process (mostly a coloring) with z. B., reactive, sulfur, and naphthol dyes . Mostly organic acids such as. B. acetic or formic acid is used, but hydrochloric acid for naphthol dyes. The amount used for acetic acid (60%) is 1 to 2 g / l.
Acidification is important to strengthen the substrate-dye bond (reactive dyes), to prevent a subsequent change in color (post-oxidation) (sulfur dyes) and to dissolve uncoupled diazo compounds, decomposition products and metal hydroxides (naphthol dyes).
See also
- To dye
- Pickling
- Acid pretreatment in the textile industry