Most of the credit cards in nationwide and worldwide use are made of one of the world's most ubiquitous substances, a plastic called polyvinyl chloride (PVC). This is the same tough, versatile plastic used for plumbing pipes and many other purposes, its biggest attractions being its durability and its lack of the volatile organic compounds (VOCs) that make some other plastics unsafe. In manufacturing credit cards, a variant of PVC called polyvinyl chloride acetate (PVCA) is mixed with additives to make a tough, shiny substance offering high abrasion resistance and a porous surface capable of absorbing the printing pigment.
The PVCA is melted and pressed into large sheets, then allowed to cool. Care must be taken during this 'curing' process to prevent the formation of defects that could cause warping or bubbling of the plastic. When it solidifies, the design and text for many rows of credit cards are printed on the sheet. For large, colored areas such as background designs or company logos, dye sublimation printing is used because it allows a wide range of bright colors that will not fade even after years of use. For smaller patterns such as text or some small security features, a process called thermal printing is used because it has cleaner edges and can make more precise, detailed designs. Some print machines perform both types of printing, allowing cards to be printed in a single process.
If the cards need magnetic strips, these are applied at this time using magnetic ink printing or hot stamping. Information is encoded on these strips at this point, since magnetic encoding will not work through the lamination that comes next.
If they were issued for nationwide use at this stage, the credit cards would not hold up to wear very well. PVCA is tough, but it can crumble or crack from heavy use. To give the cards more strength, make them less crack-prone and improve their surface texture, the plastic sheets are laminated on both sides at this stage.
After lamination, any lettering or images that need to be raised above the card's surface are added by stamping. This usually is done to the card number, since it makes the digits hard to obliterate or change.
At this point, the sheet is cut into individual cards. Security features such as holograms, ghost images and embossed foil are sometimes added to make duplication more difficult.
Though this is the process used to make most credit cards, a few cards made from other materials have emerged on the market. Plastic is quite durable, but metal is more so and gives a card an unusual, high-end appearance. Some nationwide card issuers have used metal for their high-privilege cards, giving them a great look, a substantial feel and a definite flash appeal.
Anodized titanium has been used occasionally, creating a nearly indestructible card that is extremely difficult to counterfeit. Anodizing makes these cards corrosion-resistant, ensuring that they will be intact and usable far beyond the lifetime of any one customer.
In a move that is obviously intended for maximum bling, some card issuers have made cards out of an alloy including gold and palladium. Pure gold might make the point even better, but would be too soft for practical use.
Metal composites composed of plastic strengthened with metal fibers have occasionally been used for cards. This is a compromise offering low price and increased strength.
Carbon is lighter and cheaper than metal, but has greater strength than plastic. A few high-end cards are made of it, giving them heightened durability and an unusual, noticeable look.
The next time you use a credit card, pay attention to the material and how it is made. These little tools are well-designed, and many will be used for decades before finally wearing out.