Etching of metal surfaces (steel – aluminium)

Etching of metal surfaces

Bright pickling of steel.
1 dilute the volume of concentrated phosphoric acid 3 volumes of water. In this solution, etch objects until a shiny surface is obtained. Rinse with water and additive 3 cm3 of phosphoric acid na 2 dm3 of water.

Matt etching of aluminum.
30 g table salt and 200 Dissolve g of sodium hydroxide in 1000 cm3 of water. In heated to temp. ok. 50° C solution immerse items for a few seconds, immediately after taking it out, rinse thoroughly with water and immerse for approx. 30 s in nitric acid, diluted with water in the ratio 1:1. Rinse thoroughly first with cold, then with hot water, dry in a stream of warm air.

Bright etching of aluminum.
Immerse items to heated to 85…100° C bath composition: 155 cm3 of concentrated phosphoric acid, 17 cm3 of concentrated sulfuric acid, 13 cm3 of concentrated nitric acid, 25 cm3 of water, 1 g of boric acid, 1 g of copper nitrate. Etching time:
1…4 min. Rinse thoroughly with water and dry.

Etching aluminum to a silvery sheen.
2 cm3 of concentrated hydrochloric acid make up to 1000 cm3. In this solution, etch the objects until the desired effect is obtained. Rinse with water and dry.