Selective Coating / Masking
It is possible to prevent anodising where it cannot be tolerated, but this is a relatively expensive operation and it is usually cheaper to anodise a large area unnecessarily than to stop-off.
Masking or stopping off is carried out by a variety of means:
- Plastic or rubber bungs and plastic screws are used for threads and holes.
- Special adhesive tapes can be used to mask flat surfaces or external diameters.
- Special lacquers can be painted onto surfaces that are accessible to the brush.
- The component may be immersed into molten wax. The wax is allowed to dry and it is scraped or otherwise removed from the areas to be anodised.
- Mechanical masks may be specially made for a particular job
Applying lacquered masking media
Because there are several methods available a suitable masking technique is usually found, however each of these methods have their advantages and disadvantages, they are often used in conjunction with each other to overcome a wide variety of problems. Critical areas that are either to be anodised or to be masked should be clearly identified. Specific discussions on masking, jigging and anodising are essential to obtain optimum results.
Masking is labour intensive and can be very expensive.
A combination of processes may be applied to one component by using suitable masking techniques.