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Test SolutionAssessment of white rust removal
methodAssessment of passivation performance
following outdoor exposureComments on Coating Appearance
50 g/l Sodium Dichromate + 0.1% Sulphuric Acid
Not very effective the white rust remaining was stained yellow.
Virtually unchanged white rust still remains yellow staining gone.
420 g/l Chromium Trioxide + 0.5% Nitric Acid
Effective white rust removed leaving bright. Shiny coating with black spots.
Excellent white rust resistance – no white rust, coating slightly dull.
262 g/l Sodium Hydroxide + Talc
Effective – White rust removed leaving a dark but shiny coating with black spots.Some etching which revealed spangles in the coating
Poor white rust resistance – white rust evident, coating slightly dull.
200 g/l Chromic Acid Very effective – White rust removed leaving a bright, shiny coating.
Good white rust resistance – isolated spots of white rust present, coating dull.
White Rust (or) Wet Storage Stain Removal & Passivation Methods
Prepared By
M.Sreedhar PatnaikIncharge – QA/QCVISTA