Surfaces to be tested must be clean and dry before penetrant is applied. Checkmor® 240 may be applied to the area to be inspected by aerosol, brushing, flow-on, immersion, spray or by swab dependent on the circumstances. The minimum recommended contact time for the penetrant is 10 minutes. Contact times may vary according to the controlling specification.
Wipe-off technique
The surface excess Checkmor® 240 is removed by wiping away as much as possible with a clean and dry absorbent lint-free cloth or paper. This is followed by wiping off the remaining surface excess using a similar clean cloth that has been dampened with a suitable solvent such as S76. Solvent removers must not be applied directly for the removal of the penetrant if serious loss of sensitivity is to be avoided. After removal of the surface excess penetrant, components should be allowed to dry.
Developing
The penetrant inspection process is completed by the application of a developer. When colour contrast processes are used, only developers which leave a continuous opaque background layer are suitable. This means essentially that only a wet developer such as the non-aqueous solvent developer LD 7 is suitable.
Non-Aqueous Developing
The LD7 developer is commonly applied by aerosol for convenience. Aerosols must be shaken before use and a thin developer film must be applied over the test surface. Care should be taken to build up the developer layer gradually and not to apply too much developer which may result in the masking of fine indications. The recommended minimum developing time is 10 minutes before final inspection is made, but this may also vary dependent on the controlling specifications. When using non-aqueous developers, indications often appear immediately upon application, but final inspection should be made only after the full developing time has lapsed. Inspection should take place in diffused white light of at least 500 lux at the component surface.
After final inspection, components can be cleaned using S76 cleaner.
Approvals and Specifications
For approvals and specifications, please check our website at www.aerospace.chemetall.com. Safety guidance
Before operating the process described it is important that this complete document, together with any relevant Safety Data sheets, be read and understood.
