PART A. An Overview

1. Why Decals?

It is said the first decorated T-shirt was produced in 1939 to promote the movie "The Wizard of Oz." Prior to that time, T-shirts were mostly white and considered underwear. Today, imprinting or applying a surface graphic is often all that distinguishes what are otherwise commodity products, dramatically increasing their market value. This is as true of ceramics and glass as it is sportswear. Decals are a flexible option whenever you have a surface imaging requirement.

They offer:

PRE-TESTING and certification of performance of a variety of quality assurance specifications such as metals release, durability, adhesion, and surface compatibility.

PRE-SELECTION for quality appearance requirements such as hue, gloss density, opacity, reflectance, brightness, sharpness, size, and shape.

PRE-INSPECTION for reduced manufacturing spoilage such as multiple color registration, or cosmetic flaws or defects.

LESS HANDLING since each part is touched only once even for complex and intricate graphics.

ARTISTIC FREEDOM providing detailed graphics on compound or complex surfaces.

SIMPLIFIED PURCHASING since there are fewer raw materials to acquire, inventory, and manage.

IMPROVED PLANT SAFETY by eliminating flammable printing inks or fluids, solvent odors, hazardous waste disposal problems.

Other Benefits of Decals:

PRODUCTION FLEXIBILITY AND INVENTORY CONTROL

FAST CONVERSION AND PATTERN CHANGE

SIMULTANEOUS DECORATING OPTIONS WITH WIDE TOLERANCE TO PROCESS VARIABLES

LOW CAPITAL COSTS

REDUCED FACTORY SPACE, DOWN TIME, SKILLED LABOR,
MAINTENANCE COSTS

2. How Decals Were Made

The decal starts with art work, supplied by the client or created by our own Giraphix ™design studio. Through manual or electronic means, the art is separated into black and clear positives for each printed color. These positives define the open mesh areas where the ink will pass through the screen to the decal paper.

These separations contain two types of print, half tones (small dots of varied sizes which produce shading gradients) and lines or solid areas which are scaled, repeated, and pin registered. A screen mesh and stencil emulsion which are compatible with the half tone dots and desired ink deposit are selected. The mesh is stretched taut on a frame before the emulsion coating is applied and dried. Each color's transparency is placed in contact with the framed screen under vacuum and exposed to ultraviolet light which burns and hardens the emulsion.

The unexposed (positive) areas remain soft and are washed away with water. While the screen is being produced, ink materials such as pigments, glass frit, solvents, resins, and binders, are mixed with high intensity to form a thick paste suitable for screen printing.

The pigments and glass frit, which are the only materials that remain after the firing process, are carefully selected for compatibility with the customer's ware, firing process, and end use. Printing is accomplished on automatic cylinder presses, by skilled operators. Each color is sequentially printed on specially coated decal paper and air dried, in a process that can take several days. Finally, a clear or colored cover-coat of lacquer is screen printed over the graphics to transfer the graphics during application.

Prior to shipment, each decal sheet is counted as it goes through a final quality inspection (see Inspection Criteria) and a test firing is performed. Printing and ink data along with the color separations are filed for future use and reference. The decals are shipped in a re-closable long term storage box with pertinent information printed on both the box cover and decal sheet.

3. Glass, Over-Glaze, In-Glaze

Vitricals™ are decorative markings for glass, ceramic and vitreous enamels. They are water slide decals which are applied by conventional soaking and squeegee methods. After firing, they provide a permanent surface decoration.

Vitrical™ decals can be formulated to fire onto materials ranging from low or high expansion glass to hard porcelain. The choices allow for production of many possible colors and opacities. Our state-of-the-art printing machinery can produce Vitrical™ decals in single colors. in high resolution Multiple colors (20 or more), and in process color. They can be produced from Custom artwork or from our own stock patterns.

Vitricals can be formulated to fire at many different firing temperatures which is determined by the melting temperature of the FRIT or glass portion of the printing ink.

Typical Firing Ranges
(see conversion chart)

GLASS
1. Lead Crystal: 980-1030°F
2. Soda Lime Silicate: 1050-1100°F
3. Borosilicate: 1200-1250°F
OVER-GLAZE
1. Earthenware: 1380-1470°F
2. Bone China: 1430-1500°F
3. Soft Porcelain: 1400-1520°F
4. Hard Porcelain: 1430-1580°F
IN-GLAZE
1. HIGHLY GLAZE DEPENDENT- 1800-2400°F

NOTE: While all vitreous markings are durable by nature, with good adhesion, abrasion and chemical resistance, in-glaze are the most durable and best suited for extreme conditions. They typically are used for most commercial dinnerware and many tile applications.

4. Water-Slide -Pad Transfer

Water-slide decals (Vitricall™) are applied by hand and have the most flexibility to conform to complex and compound shapes.

Heat Transfer (Vitramark™) decals are applied by machine where a soft heated pad picks up the graphics from a hot plate which has melted the wax coating on the paper. When it makes contact with the surface to be decorated, the wax re-freezes, adhering the transfer for firing.

5. A List of our Products and Trademarks

 

VITRICALS™	High quality transfers for Ceramic Glass, and Vitreous Enamel
VITRAMARK™	Machine applied markings and pad transfer equipment.
D-VISE™	A fully adjustable, rapid clamping fixture. It frees the decorators hands and permits 360 degree rotation
PHOTOCAL™	Digital output proof in decal form to produce compelling working models of your idea.
TEKNICAL™	Technical application transfers. They may possess mechanical, electrical, or chemical properties. As active decals, they combine form with function.  Touch-screen capacitors, Bake on Identification, Electrical Markings, Conductive transfers
UNIMARK™	Decals Designed for Raw glaze application

6. Finishing, Shipment, Storage, and Handling

One issue commonly questioned but more often a primary cause of defects in the fired product is decal storage method. Our fire on decals, trade-marked Vitricals, are composed of a variety of materials, each with unique and varied sensitivity to changes in environmental or atmospheric conditions. The most stable materials are the frits and pigments, which, in their powder state require extreme temperature or corrosion to change their form. However, the dry organic materials in which these powders are encapsulated and the paper onto which they are printed are quite sensitive to storage conditions. The water soluble starch adhesive paper coating and the paper fibers themselves are both sensitive to temperature and humidity.

The dry cover-coat and printing medium which act as transfer film and binder are composed of trace solvents, plasticisers, and dissolved polymers. These organics are sensitive to oxidizers and ultraviolet light. When left in open air for extended periods of time, the organics will "dry out" often resulting in decal tears during application and fired defects such as pits. (Pits in the fired ware can result from many causes, which will be discussed in a later chapter). Fortunately, "dried out" old decals can be salvaged at a fraction of their original cost by having the manufacturer print a cover-coat refresher.

Finally, decals, which are subjected to pressure, from horizontal stacking and heavy weights, can cause the decal sheets to stick together and the organic materials to bind and deform. Waxed slip-sheets and non-blocking over-coats help prevent stuck sheets. We ship slip sheeted decals in boxes and plastic bags designed to be used as permanent storage containers. The boxes should be stored closed, vertical, and in air at 55 - 80°F and 40 - 60% relative humidity. It has been reported that decals have been applied and fired successfully after being stored properly for several years.

Note: To ensure longest possible life, decals should remain stored vertically in their box. Do not expose decals to extreme cold or hot temperatures or dry and humid environments. We recommend storage at 55-80°F and 40-60% relative humidity.

Criteria for inspecting decals
The following list represents the nine criteria for which each deal is checked during final inspection.

1. REGISTRATION
Registration targets should overlap. Colors align uniformly. Abutting fits and color traps must leave no gaps around printed areas.

2. COMPOSITION
Size, shape, layout, and printed text must match the standard. There; must be no distortion, enlargement or reduction from the original.

3. REPRODUCTION
Halftone dots must show contrast, sharpness, and detail. Solid colors must be uniform and dense. The print should match the standard.

4. SHEET UNIFORMITY
No variation across the sheet or from sheet to sheet.

5. STRAY OR MISSING COLOR
There must be no extra printed areas or holes.

6. INK FLAWS
There should be no smudges, splatter, ghost images, pinholes, or fisheyes.

7. COVER-COAT FLAWS
There should be no pinholes, fisheyes, splatter, missing areas, thin coverage, lumps, smears, or off registration.

9. FOREIGN MATTER
There should be none. Fibers, dirt and airborne dust must be kept to below a minimum acceptable level.

9. CREASES OR TEARS
There can be no folds, perforations, creases, or tears in the paper through the decal.

Die Cutting
Die Cutting is a process by which individual decals or groups of decals can be cut and bundled in a defined shape. This can include center notches to help align decals during application. Our decals are not supplied die cut, but such service is available at extra cost.

Editions and Lot Numbers
Each of our decal sheets includes a lot number, typically in the form of XYYYY; Where X is a letter code and YYYY is a four digit number (132045, for example). This lot number is a key tracking number used to file process and billing information. From it we are capable of tracking: ink formulations, creative materials, printers books, and shipping records to name a few. If you cut decals from the printed sheet, it is important to keep this lot number with each separate decal bunch. It is not a good idea to combine decal of different lots until you have confirmed performances of the decals.

A look at an inspected sheet
The decal sheets, which are shipped to you, include not only the lots number information, but also an inspectors mark. This mark is a colored check of red, orange, yellow, green, bright green, crimson, purple, or blue.

Any defective decals on the sheet will be crossed out in the color of the inspector's pen. Each inspector keeps a tally of cross outs and these are subtracted from the total to yield and "equivalent sheet" for billing purposes.

For those who inventory decal sheets produced by us before October 1995, our old marking system used a blue inspector number stamp and either a black or red marking pencil.

The inspectors mark (pen color or number) allows us to track service related issues should the customer encounter any rejects. When reporting rejects to us, it is important to provide the lot number and inspectors identification.

7. Application

How to apply water slide decals
WET THE DECAL in a pan of water, which will cause the paper to curl. Remove to a flat surface and let the decal flatten (typically about 20 seconds). Tap water may be used for wetting. But, when high mineral content is present, de-mineralized water avoids fired defects. A soluble food grade starch paper coating adheres the decal to the ware before firing. Over-soaking the decal to float free of the paper must be avoided as this may cause pre-firing adhesion to be lost. Replace water when it appears cloudy. When the decal must stretch over a curve, soak the decal and/or ware in warm water allowing the decal lacquer to become more flexible and easier to apply.

 

Decorating Squeegees Application squeegees made of soft rubber or urethane are used to press the decals onto the surface while removing the water. They can be obtained in a variety of shapes. Lubricating the squeegee with the residual gum left on the paper can prevent tearing of the decal. We offer extremely durable decal decorating squeegees made from tough 70-durometer cast polyurethane rubber. These squeegees are 5 mm thick cut nominally 26 by 2.50 and feature both a hard square edge and a soft chisel edge. They are well Suited to flat or intricate hand decoration and fit comfortably to the operators hand.

D-Vises and other Fixturing Tools
Many decorators will fabricate holding fixtures for their ware to speed decal application times by freeing up a decorator's hand. Typical attributes of such fixtures include quick load and unload process, low investment cost and easy to store. We developed a fixture trademarked D-Vise which, in addition to the other attributes, offers flexibility. Standard, manual and pneumatic models rotate a full 360 degrees and can easily adjust to clamp anything from shot glasses to lamp bases.

Vitramark and other Pad Transfer Machines

   There continues to be increasing interest in the pad transfer technique of decal decorations. There are highly automated transfer machines on the market starting at prices from $18,000 to $125,000. Philadelphia Decal offers a Vitramark™ machine to introduce low cost flexible automation into hand decorating production lines or to support users of the highly automated machines at a research and development level. Machine operating principles are the same and each uses the same types of decals. Unlike the more expensive machinery, the Vitramark™ pad moves manually between indexed stations by the decorator's hand in a simple and fluid operation. 

Pad transfer utilizes a flexible heated silicon pad to pickup a multi-color decal decoration from heated waxed paper. The pad then places the decoration onto a flat, cylindrical, or irregularly shaped room temperature glass or ceramic surface where residual wax on the decal underside freezes to hold the decoration in place. Unlike waterslide decals, no drying time is required and ware is ready for immediate glass, over-glaze or in-glaze firing. Also, there is no squeegee or alignment time required. So, decorating speeds per operator are substantially increased.

Application Speeds

Application speeds can vary depending upon decal characteristics, specific ware shape, and decorator expertise. The following is a general guide.
PRODUCT	WATERSLIDE Pieces P/Hour	PAD TRANSFER Pieces P/Hour
• Spot Decal 100-200	100-200	800-1,400
• Small Bottle/Tile	150-300	1,000-2,000
• Full Wrap Mug	60-120	500-1,000
• Full Skin Collector Plate	30-60	N/A
• Lamp Base	40-80	N/A

8. Proper Firing

An understanding of the dynamics of a proper firing requires the following knowledge of decal chemistry and basic kiln technology: Remember that the objective in firing ceramic decals is to melt and fuse tiny inorganic particles of glaze pigments to the substrate in such a way as to achieve the desired appearance and properties. Each decal component has a functional purpose and can be affected by firing conditions. An improperly fired decal can result not only in poor appearance, but also in poor adhesion, detergent durability, toxic metal release, and abrasion resistance.

Our decals are produced in a screen printing process and contain organic adhesives, printing oils, and cover-coat that are designed to vaporize and combust during the firing process. These materials, when fired properly, leave no ash deposits and will not affect the final appearance and/or properties of the decoration.

Vitrical™ water slide decals are printed on a starch coated paper and applied using water which allows the decal to transfer. These decals must be thoroughly dried at temperatures less than 100°C (212°F) before firing. Otherwise, boiling water will lift and pit the decal's surface during firing.

Vitramark™ pad transfer decals use a special waxy hot melt adhesive and can be fired immediately after application. It is important that the graphical portion of a decal does not overlap the cover-coat edge of another decal.

The organic materials burn away during the firing in the range of 150-350°C (300-750°F). If the firing is too rapid, pits in the final decoration can result. This pitting due to rapid fire occurs because the colors melt and begin to fuse to the ware before the organic compounds completely vaporize and burn away leaving the organic trapped in the decal. However, unless the decal is placed in a flame, it is rarely the maximum rate limiting factor in the firing process. More typically, it is the ware which must be fired slowly due to its expansion, strength, and heat transfer characteristics.

Once the organic are burned off, only the inorganic powdered materials remain on the ware. These powders sinter, melt and fuse to the ware in the upper temperature range of the firing cycle. About 90% of the powder is glass frit or flux, selected for (among other criteria) its compatibility with the ware glaze. The other 10% are usually a variety of pigments, selected for their appearance, chemical properties, and compatibility with the frit and firing conditions.

Firing effects the decal pigments, composed of a mixture of metallic oxides. These oxides, when properly fired, exhibit their desired color. If under-fired, the powdered pigments will not fully melt and disperse in the flux. Instead, they may remain as a powder and/or produce a dull or matte surface, which will easily scrape away. Under fired colors may appear weak as well. If over-fired, the pigments may lose or change their color because of their temperature sensitivity (some pigments are sensitive to peak temperature differences of I 100°F and less). When over fired, the pigment mixture may exhibit the color of one component or it may develop an entirely different color altogether. Therefore, reliable temperature control is required to achieve satisfactory firings. If loaded sections of a kiln or belt furnace are too close to hot connective gas flows or other heat sources, they may become over-fired. In an electric box kiln, "hot spots" can occur along the upper edges and areas close to the heating elements. Proper sensor location and control equipment help maximize the capabilities of firm,-, equipment. Independent temperature recordings with sensors placed adjacent to the ware at strategic locations in the kiln provide an audit and can help troubleshoot most firing problems.

Proper firing requires both time and temperature to allow the organics a chance to bum away and the frit materials to absorb the energy necessary to melt and fuse to the ware. It's important to realize that heat energy flows from high temperature air to low temperature bodies and that in firing conditions, the surface temperature of the ware lags significantly behind the air temperature of the furnace in accordance with the ware/air heat transfer characteristics. The best way to assure proper firing is to allow sufficient time for heat to "soak" the ware at a given temperature. Thicker ware requires longer soak time. Typical glass and ceramic tableware require a five to twenty minute soak depending on thickness.

Kiln atmosphere can affect decal firing, especially during organic burnout when oxygen is required for the combustion process. Generally, fuel fired kilns, which heat by combustion, have sufficient oxygen for organic burnout. However, electric kilns require ventilation during the first stage of decal firing. Without ventilation, electric kilns tend to produce reducing or oxygen deficient atmospheres because the organics deplete oxygen as they burn away. To insure proper firing, the kiln must be free of dust and dirt particles as well. These particles can settle onto the cover-coat or the molten glaze and decal during the firing. Inorganic particles can often be observed as specs on the cooled ware; whereas organic particles will burn away but can leave pits where they rested.

Furnace and glass engineers should be available for startup and consultation when defining or troubleshooting a firing process. Philadelphia Decal offers such engineering services in addition to comprehensive product Support and laboratory testing services.

Periodic kilns - Belt and Roller Lehrs.

9. Cost guidelines

How decals are priced
Decal costs are based on three primary factors, size, quantity, and the number of colors. The first two are often very closely related because the size will effect how many decals will actually fit on a sheet or within a defined area. Customers are always encouraged to use the sheet geometry to their best advantage. We attempt to spot weak layouts and make suggestions to improve sheet yield whenever we can.

Ruled paper sheets called "Layout Forms" for layout planning, show size and spacing limits and are available on request. A computer generated Layout conformation, in quarter scale, can be taxed to represent any proposed layout (see Layout Options).

Premium for precious metals and special effects
Many unique materials may be used to distinguish a design by adding texture or otherwise enhance the appearance. Popular materials include precious metals like gold or platinum. These are printed as organometallic pastes which when fired are reduced to thin layers of high purity (23 carat) base metal. Prices are determined by metal concentration of paste and yield (printed volume per unit of area). It will fluctuate with the market prices of these materials.

For those who pay a premium for decals that contain precious metals such as gold and platinum, collection and refining of decal scrap should be considered. While it does not pay to send decorated ware to a refiner (due to the low weight yield), decals can provide yields of several dollars per pound of scrap. Therefore it is worth collecting such waste. Typically, refiners require a minimum of two 55-gallon drum of material before they will process. However, even if it takes a year to collect the material, the small amount of effort and floor space can easily pay for itself.

From our studies, we have seen substantial variation in yields from the refiners, so it is worth shopping around and sending split samples if possible. Typically, the refiner will provide collection drums and transportation of the material. Processing time is typically 3 to 4 weeks to settlement. Refiners will require you to specify what precious metals are present in the decal scrap. Obviously, gold bearing decals should be tested for gold; however, few people realize that platinum inks contain substantial amounts of gold and palladium as well. Philadelphia Decal would be happy to help you establish a gold reclaim program.

Proofing
Proofing is an exercise that results in the production of physical samples of the decal desired, usually 12 copies. It insures that all of the color development, art, and printing techniques are correct and suitable for the intended purpose. It is used to establish an approved standard to which all future production will be measured. Production decals will be printed after approval of the proof.

Proofing is not required for reorders or where line art is supplied in "screen ready" form if the colors have been tested and approved. The customer may otherwise decline it only upon the execution of a waiver.

Creative Art Services (see Girafix) and color separations are quoted separately and incurred prior to proofing.