Instructions for Non-Ferrous metals: When bonding metal to metal, priming is unnecessary. Clean surfaces. To achieve a permanent bond, rough up highly polished surfaces slightly by sanding. Use concentrated Weldbond and delay bonding until maximum tackiness has occurred- no more than 3 to 4 minutes. The strength of the bond you get will depend on the size of area you're working with. The larger the surface area, the stronger the bond. Curing time is most important. Avoid bonding small weight-bearing surfaces.