Surfaces must be clean, dry free from all defective or poorly adhering material, dirt, grease, wax etc. Degrease where necessary with a suitable oil & grease remover. Rinse with clean water to remove residues. Apply a liberal coat of Dulux Trade Mordant Solution by brush and allow to dry. If the surface fails to turn black overall, the most likely cause is contamination of the surface or the presence of a factory applied pretreatment. Rinse the surface thoroughly and abrade, using a suitable abrasive paper. Remove all residues and re-apply Dulux Trade Mordant Solution. Avoid over-application as pooling of the wash will result in the formation of a fine brown deposit of copper. After treatment the surface must be rinsed with clean water to remove all residues and then allowed to dry before priming. The pre-treated surface should be overcoated with an appropriate Dulux Trade metal primer within 48 hours or before contamination can recur.