Embossed Film

Embossing Basics

Definition of embossing:  In the broadest sense, it means to change a surface from flat to shaped, so that there are regions that are raised up from a background.  This meaning would seem to encompass areas that are normally not called embossing:  carving figures into the face of a mountain (like Mt Rushmore), or engraving a steel block.  On this website, I use the word "embossing" only as it applies to thin and malleable materials.  Since the opposing surfaces of a thin material are very close to each other, each raised area on one surface is matched by a recessed area on the the opposite side, and vice versa.  One exception to this is sometimes called "pattern pressing" or "blind embossing".  This occurs when areas of one surface are recessed while the opposite side remains flat, causing the material to become thinner in those areas.  This is typical when embossing leather, for example.

Materials that are embossed:  Just about anything that is thin, flat, and malleable can be embossed.  This includes paper, plastic film, metal foil, nonwovens, textile fabric, leather, and even glass.  These materials may be provided in continuous form (like paper unwinding from a roll), or in discrete form (cut into individual sheets before embossing).

Purpose of embossing:  Sometimes embossing is done for purely decorative reasons.  However, in most cases, the purpose of embossing is to change the physical characteristics of the material.  Embossing a metal foil with a fine texture pattern makes it much easier to handle the foil within the machine that wraps it around a piece of chewing gum.  Embossing a plastic film changes its elastic properties dramatically.  Embossing tissue paper improves absorbency and flexibility, but almost always at the expense of strength.  Embossing increases the overall thickness of the material.

Methods of embossing are often determined by the properties of the material, and how it is provided.  The material may be malleable or fluid, or somewhere between.  It may be provided in continuous form (without breaks), or in discrete lengths or pieces.

• For malleable materials, a permanent shape change is imposed simply by the application of force.  This usually has a very significant effect upon the mechanical properties of the material.  Most tissue paper is embossed this way, while the paper is completely dry.
• For fluid materials, the embossing step starts out more like casting onto a mold while the material is still fluid, and then the material is changed from fluid to solid.  This reduces the effect of the embossing upon the strength and elasticity of the material.  In the case of tissue paper, the fluid state is the suspension of paper fibers in water, the mold is the forming wire, and the material becomes more solid as the water is removed.
• Some embossed materials are somewhere between malleable and fluid.  For instance, tissue paper can be shaped after it is formed, but still very wet.  The results are much different from traditional "dry embossing".
• When the material to be embossed has been cut into discrete lengths, it is usually necessary to employ an intermittent method like stamp embossing, where the sheet is pressed between two plates.
• When the material to be embossed is provided in continuous form, without breaks, then the preferred method is rotary embossing, where the material is passed between embossing rollers.  Rotary embossing is much, much faster than any of the intermittent embossing methods.