In the early days there were many HID lamps where the caps became loose due to the high operating temperature. The reasons was that there was no cement type that had both good adhesion to glass and to metal. Since basing cement is extruded onto the inner wall of the cap shell, in the 1980s one of the Sylvania engineers was inspired by the then popular multicolour striped toothpastes, and patented the concept of a composite capping cement. If i remember rightly the white cement is silica-rich and forms a good bond to the glass, while the green is shellac-rich and forms a superior bond to the metal. Of course during life half of the cement will lose its adhesion on one side, but it can no longer crumble and break away due to the adjacent stripe that mechanically fixes it in place. The result is a considerable improvement in cap torsion strength at end of life.
Soon after this development a further improvement in single-component high temperature capping cements was made by Glassbond of the UK. It has since become standard to use that (or the lampmakers’ own-made slight variants), and the striped lamps were not made for very long.