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Surface Preparation for structural bonding - Metal bonding

Thoroughly clean the surface with a suitable solvent to remove all grease, oil and dirt. Grit blast surface area with 8-40 meshgrit, or grind with a course wheel or abrasive disc pad to create increased surface area for better adhesion (CAUTION: An abrasive disc pad can only be used provided white mesh is revealed).  

The desired profile is 3-5mil, including defined edges (Do not ‘feather-edge’ epoxy).  Note: For metals exposed to seawater or other salt solution, grit blast and high pressure water blast the area, then leave overnight to allow any salts in the metal to ‘sweat’ to the surface. Repeat blasting to ‘sweat out’ all soluble salts. Perform chloride contamination test to determine soluble salt content (should be less than 40ppm). Clean the surface again with a suitable solvent to remove all traces of grease, oil, dust, or other foreign substances from the grit blasting. Repair surface as soon as possible to eliminate any changes or surface contaminates  

In summary:

1. Degrease 
2. Abrade (for best results) 
3. Degrease  
4. Apply primer  
5. Allow primer to dry to just tacky (approximately 40 - 90 minutes @ RT) 
6. Cast PU and allow material to cure

A properly prepared substrate is essential to achieve consistent bond performance. 
A suitable solvent or cleaning agent prior to the application of the primer should remove all oil, grease and other soluble 
material from the substrates.  
Rust or scale or other lose debris should also be removed by mechanical or chemical methods.  
Grit blasting, mechanical abrasion or chemical etching will aid the adhesion of the primer to the substrate, and will significantly 
increase bond strength. 

Primers can be applied by; dipping, brushing or spraying.  
Spraying may involve the dilution of the material with a suitable solvent  

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