subject: Double Faced Decals; What Are They And How Are They Made? [print this page] The term decal is the shortened version of the word decalcomania. A decalcomania was a decorative technique where artist's images of prints and engraving, could be transferred onto pottery to decorate stoneware. The invention of taking an artist's rendering from canvas and printing these images onto a medium to decorate ceramic pieces was attributed to Simon Francois Ravenet. Simon was from France and he was an engraver who immigrated to England. After arriving in England circa in 1750 he perfected this transfer process.
This printing process of decorating ceramic pieces was imported to the United States in about 1865. In the United States this process was popularized during the ceramic decorating craze of the mid-1870s. In the United States the word decalcomania was shortened to the version we use today "decal".
The decals today are screen-printed on a plastic substrate (screen-printing is a type of printing that last in extreme environments and resist fading by the sun). The plastic substrate can come with all types adhesive to adhere to all types of surfaces. The types plastic substrates are legion and a few are household terms, know as vinyl (AKA PVC), clear Mylar or clear polyester (clear polyester is Mylar's generic name).
There are three types of decals, the first is known as face-up decal (printing industry jargon) also know as single faced decal with back adhesive for outside window mounting. The second is known as a face down decal (printing industry jargon) also known as a single faced decal with face adhesive for inside window mounting. The third kind is the double faced decal. The face-up decal can be used in many locations and adhered to many surfaces like: windows, doors, lockers, notebooks, and automobile bumpers. The face-down decal is used to manufacture a decal with the adhesive on the face. When the decal is applied to the inside of the window the image or graphic is visible from the outside of the window.
The 3rd is the double faced decal and is really a combination of the (two) described above; using a white polyester barrier film and a clear polyester film (more on this later).
Until the middle of the 1980's double faced decals where printed utilizing only a clear polyester product. The double faced decals of this era were basically a build-up of ink on one side of the clear polyester. The double faced decal has two images one that is seen through the adhesive side of the material and the 2nd image was printing over the 1st image. If the decal was to be printed with black text on a white background and the message was "Hot Dogs Sold Here" this message was printed as a mirror image like this: "ereH dloS sgoD toH" on the clear polyester then a white field was printed over the black text in mirror image. The text was printed as a mirror image because when it was seen through the clear polyester it would look correct. The 2nd face is printed right reading bearing the same message "Hot Dogs Sold Here". This was printed on top of the a 2nd white field printed over the mirror message already printed. In between the two white fields a silver opaque ink barrier was printed so the decal would not be translucent. This is done because silk-screen inks are not totally opaque. The silver metallic ink was printed between the two white fields so when the decal was mounted to a window you would not see a ghost image of the other side.
Most double faced decals are not printed this way any more. The inks screen-printers used were engineered with lead as a component which gave the inks a certain amount of pliability. In 1979-1980 lead was eliminated as a component of screen print ink, by order of the Federal Government. The screen-print inks had to be re-formulated without lead.
When screen-printers used the new inks without the lead component to manufacture double faced decals, the many layers of inks were no longer elastic so they would regularly crack.
A new technology was invented and this new product was not an ink but a material known as a barrier film. The barrier film is a plastic sheet with adhesive that is totally opaque.
The screen-printer prints on the barrier film which is white polyester and the image printed is right reading. Then the mirror image is printed on a clear polyester film, and then the printer laminates the clear polyester to the adhesive side of the barrier film. The result is you now have two faces that read correctly.
Double faced decals have a much cleaner look, because if a vinyl decal or clear polyester decal is employed and adhered to a window these will have a large white field facing toward the inside of the retail store. The double faced decal has the image on both sides, thereby creating a pleasing advertising piece.
The double faced decals because it has a second image are viewed by the consumer when they enter the store and when they leave the retail outlet, too.
