Observations

Test solutions and classification

NH₄Cl (100 g/L)

HCl (3%) et KOH (30 g/L)

HCl (18%) et KOH (100 g/L)

No visible change

Class A

Class A

Class A

Visible change on the cut edge

Class B

Class B

Class B

Visible change on the cut and uncut edges and on the workpiece surface

Class C

Class C

Class C