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| Disc Identification & Labeling Methods |
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Inkjet Printing Inkjet printing can produce quality print results – but at the expense of some inherent drawbacks. Disc media for inkjet printing uses a semi-porous coating conducive to absorbing and holding liquid ink droplets. Inkjet disc printers can print directly to inkjet compatible discs, while standard inkjet printers can print to pressure-sensitive disc labels. Discs used for direct inkjet printing typically cost more. Replenishing inks can be expensive and some printers have proprietary cartridges preventing refills or using off-the-shelf generic brands. These two factors alone can increase disc labeling costs. Inkjet print resolution claims can be mystifying. Color printing draws ink from multiple cartridges – each forming a small dot. Dots are placed in close proximity to visually create an area of desired color. A printer claiming a 1,200 DPI resolution may draw ink from 4 (or more) cartridges to print a specified color. In this example, print resolution using four cartridges could be calculated by dividing the stated 1,200 DPI by 4 cartridges – or 300 DPI. Inkjet printing can smear when subject to moisture or high-humidity. A transparent plastic overlay on discs can prevent smearing – but adds additional cost. Finally, because inks require time to dry – sometimes up to 24 hours – shipping or handling discs prematurely can also cause ink smearing.
Silk-Screen & Offset Printing Using UV-curable inks for silk-screening discs offers colorful labeling options, typically used in large volumes. The economics associated with job set-up – making individual color-screens or plates from artwork separations – necessitates amortization over larger quantities to justify low cost. Screen-printing discs can accommodate up to six colors resulting in high quality. Modern screen printing equipment is capable of 70 discs per minute or faster. Silk-screen inks used for disc printing must be chemically compatible and stable with disc surfaces. Offset printing provides higher quality for photographic printing, but the cost is usually higher. Both methods typically utilize top-quality graphic or artwork design.
Thermal Printing Thermal transfer disc printing permeates a thin polymer onto disc surfaces. Discs are pre-coated with special formulations to enhance adhesion. The process is permanent and produces high quality. Single-color thermal printing is well suited for simple text labeling, line-art and logos. Two-color and three-color thermal printing is also possible. It’s not recommended for complex bit-maps or high resolution graphics. Thermal surface printing is inexpensive, looks professional and produces clean text and clear lines.
Thermal Retransfer Printing Thermal Retransfer is used for spot-color disc printing. It’s similar to thermal printing with an additional transfer step. It produces full-color with high-quality results – but is more expensive than screen and offset printing. A final transparent disc-overlay is often used. Depending on the specific thermal retransfer equipment and disc quantity printed – among other factors – printing full-color with thermal retransfer may be less expensive or costlier than alternative methods in quantities of 1,000 or less.
Pressure-Sensitive Labels An accepted method for full-color or black & white disc identification is with pressure-sensitive labels. Pressure-sensitive labels made with quality materials and adhesives formulated for disc-surfaces, look attractive and provide a professional appearance capable of high-resolution results. Pressure-sensitive labels are a viable disc identification alternative used in non-archive disc distribution projects. High-gloss white or transparent plastic labels can incorporate simple or complex full-color designs – including photographs. Commerical-grade pressure-sensitive labels can rival other disc identification methods – usually at less cost. Labels mounted and centered properly on discs are permanent and operate reliably in most standard tray-load drives and consumer playback equipment. Labels produced with laser printers and colored plastic toner – instead of liquid ink – permanently 'fuses' images with labels to avoid smearing. When pressure-sensitive labels are used on CD discs, they provide another benefit. Labels automatically deliver an additional layer of surface protection for the vulnerable 'reflective layer' located just below the surface on CD discs. Pressure-sensitive disc labels are durable and suitable for many labeling requirements – but SHOULD NOT be used on discs for archiving and long-term preservation having one-of-a-kind critical content. Some slot-load disc players – like those in vehicles – could experience mechanical hang-ups if labels are damaged, degrade or layers delaminate. Paper labels can absorb moisture, dry-out over time and degrade. Attempting to remove a fixed pressure-sensitive label from a CD will render the disc unusable and content will be permanently lost. Any disc having a damaged pressure-sensitive label should have its content transferred to a new disc. 919.552.5525
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