Description

SC CAUSTIC-AD is an etching modifier, neutral powder additive for conventional caustic etch baths. Its use enables the anodizer to let the aluminum concentration in the etch bath climb until it reaches an equilibrium with drag out - usually in excess of 130 g/l. This eliminates the need for dumping or decanting the bath to reduce the aluminum concentration. A conventional caustic etch bath must be kept at a lower aluminum concentration to maintain etch quality and to preclude the possibility of sudden aluminum hydroxide or rocklike alumina precipitation.

Even at high aluminum concentrations, SC CAUSTIC-AD ensures an attractive, uniform matte finish without dumping and without danger of sudden aluminum precipitation.

Performance

SC CAUSTIC-AD provides a clean, uniform matte etch, which levels die lines and hides grain boundaries, all at a high aluminum concentration.

Operation

Operational parameters for SC CAUSTIC-AD are as follows:

• Caustic Concentration: 50 - 70 g/l (60 g/l recommended)
• SC CAUSTIC-AD concentration: 14 - 20 g/l (17 g/l recommended)
• Aluminum concentration: 20 - 150 g/l (aluminum concentration in the caustic tank higher than 150 g/l requires at least 140 g/l of caustic concentration so that precipitation from the excess amount of aluminum will be minimized).
• Temperature: 130 - 150°F
• Immersion Time: 7 - 15 minutes

Cost

• Installation of SC CAUSTIC-AD etch modifier costs approximately $0.15 per gallon of etch tank capacity.
• Maintenance costs average $0.07 per pound of dry caustic consumed in the etch process.

Benefits

• Excellent results are achieved on tubular extrusions, where heat can be a problem.
• Aluminum hydroxide is not precipitated, and caustic is not regenerated spontaneously. Therefore, bath control is more predictable.
•  SC CAUSTIC-AD contains no chromates or fluorides. and suppresses caustic fumes.