Finishing – refers to the technology and material from which the front side of the pin is made
Sometimes called epola or hard enamel, cloisonné is stamped out from a sheet of copper. The stamping leaves recessed areas, or pools, which are filled with enamel powder and high fired at 800 - 900 degrees. After cooling, the surface of the pin is ground down to a smooth finish and then the copper usually is plated. Nowadays the manufacturers use a cheaper technology called Imitation Cloisonne – I think the main difference is in the filling material and the lower firing temperature. The final vision is the same and only a specialist can catch the difference.
The process is like of cloisonné enamel, but the areas of color are filled with soft enamel (sometimes paint). Unlike cloisonné, the areas of color rest below the metal strip surface, which can be felt when you run your finger over the surface. I use the same term for photo etched pins. In the photo etch process, only the shape of the piece is stamped out. The design on the face of the pin, is chemically etched into the base metal, then color-filled by hand and baked or just painted.
When stamped out pins or photo etched pins are colored with soft enamel or painted and after that are covered with protective epoxy
Screen printing, (silk screening) is produced by applying each color to the metal base using a "silk screen" process. A very thin epoxy coat protects the color material from scratching.
Offset printing, allows for bleeds and blends of colors, as is used in magazines. The colors are printed in the traditional CMYK process. This style can be used for complex art and photo reproduction. An unlimited amount of colors can be used.
The printing process as above is applied on a paper or plastic label which is fitted into the pin area and then covered either by epoxy or other plastic material.
A campaign button is used in an election as political advertising for (or against) a candidate or political party, or to proclaim the issues that are part of the political platform. Political buttons date as far back as President George Washington. Usually they have been attached to the buttons hence the name came. Nowadays they are widely used and have pins on the back and are celled pin-back buttons.
Closure – refers to the type of fastening the pin to the lapel.