Decorative Techniques

Technical descriptions of de bossing/embossing, silk screening and foil stamping:

Embossing/Debossing
Embossing and debossing can either press a design below the surface of a material for a three dimensional effect or prepare the material for further decoration by flattening the grain of the material. This process is accomplished using heat and the pressure of a debossing press and die. The die, typically made of brass, has the designed countersunk into it and is uses with a reverse form of the composition material. This is the same as a top and bottom die or male/female die except the composition is generally cheaper than a second die. When the material is compressed under heat and pressure, it is left with a permanently lowered design.

A wide variety of materials can accept debossing including genuine and artificial leathers, coated fabrics, specialty papers, boards, and vinyl (if done dielectrically). Debossing is adaptive to a range of requirements. The debossed area may have sufficient detail to be distinguishable, or can further enhanced by additional decoration. Thus, the debossing/embossing is often combined with decorative processes such as silk screen printing and/or hot stamping. This adds more color and attention getting value to the three dimensional effect. Striking, attractive, and permanent accents enhancing the layout may be achieved with these decorating techniques.

Silk Screening
Silk Screen Printing is a stencil (direct image) method of printing and is believed to be the oldest form of printing. Several materials are satisfactory for screen printing. Nylon, dacron, organdy, and taffeta are a few fabrics used in today's commercial screen shops. The use of stainless steel and other fine wire mesh materials is also popular. Actually, any porous material through which paints can be forced will work with varying degrees of success and quality. The chosen material is stretched tightly over a frame and all seams are sealed to avoid leakage of the paints. The material is then coated by an emulsion, usually made of silver salt suspended in gelatin. When the emulsion is dry, a positive film of the desired design is placed on the coated screen. With the use of a vacuum table and high intensity light, the emulsion is "set" in all areas not covered by the black positive film - in other words, all areas exposed to the light are hardened.

The screen is removed from the light table and that area covered by the film positive is washed clean of the emulsion. This leaves the desired image that is to be printed on the product. This finished screen is then mounted on to the screening equipment. A make-ready and material stops are properly centered on the screening table so that the image will appear in the proper location of the material. The proper paint color is chosen and the screen is flooded with paint. A rubber squeegee is used to force the paint through the openings of the screen.

Depending upon the types of inks used, the coverage and the material to be screened, in the "air-dry" system it may take from a few seconds to 24 hours for the paint to be completely dry. Most commercial screen shops have some type of drying system to speed this process. Most often it is either a gas or electric drying system used in conjunction with a conveyor so that when the screened materials pass through the "air tunnel" and on to the end of the system, the paint is dry enough to stack without offsetting and smearing.

Today, many commercial screen operations exclusively use UV (Ultraviolet) drying systems. In this process, UV paint is used and the conveyor passes through a UV light tunnel, allowing the paints to dry instantly. With an air-dry system, inks frequently dry on the screen while being worked. The operator must make sure that the screen stays clean so that part of the image is not lost.

Foil Stamping 
Foil Stamping is achieved with the proper combination of heat, dwell, and pressure required to transfer colored foils from a carrier to the material being printed. The pressure and heat dwell setting required to foil stamp can be problematic in that items tend to distort the image if not properly controlled. Stamping large solid areas combined with smaller detail is not a proper foil stamping technique; the two require totally different make-ready as well as machine settings.

In production, the die is mounted to the platen (press head) which carries the radiant heat. This heat is then transferred to the mounted die. The foil is fed between the die and the material to be imprinted. Through the proper heat, pressure, and dwell the colored foil is transferred to the material.

The above is compiled from Richard D. Simmons' book, "Custom Looseleaf - A Dynamic Industry", Published and copyright by Small Business Acumen, Inc. 1992. PP: 37-39, 55-56, 76, 82-83, 102, 105-112.