Enamels have a durable, gloss finish and can be used both inside and outside. They have excellent hiding power, so they are suited to covering older signs. Water-based enamels can be used on heavier paper mediums such as cardboard or posterboard. Enamels are not suitable for thin paper mediums.
Bulletin Colors also have a gloss surface, but are thinner than regular enamels and do not provide as high a level of coverage. They are suitable for fresh surfaces, for redoing older signs, and for covering large surfaces. Bulletin colors should only be used on a primed surface.