The paper stock is heavier and thicker than typical printing/writing papers. It has some rigidity but is still flexible enough to bend slightly without damage. This helps the cards maintain their shape and structure through years of being shuffled, sorted, and placed in albums. They are not as flimsy as typical photograph paper or book paper.

The paper fibers are densely packed and strongly bonded together during manufacturing to give the cards high tensile strength, tear resistance, and fold endurance. This helps the cards withstand repetitive creasing from being opened and closed as well as casual abrasions from fingertip oils and accidental rubbings against other surfaces over prolonged periods.

The paper surface has a smooth, non-porous finish that prevents ink from feathering or bleeding during printing. Minor abrasions on the surface from occasional mishandlings are less likely to damage underlying ink layers. Edges and corners tend to hold their shape nicely compared to more delicate paper types.

Bright white or cream-colored papers are most commonly used as the substrate. This provides high optical brightness for maximum color pop and clarity of the printed graphics and statistics. It also forms a high-contrast neutral backdrop that prevents distracting discolorations over time from sunlight, smoke, grime, or other aging factors.

Besides paper composition and weight, post-printing surface coatings may also be applied. Minimal aqueous coatings can protect the inks and prevent fingerprints or other marks from readily absorbing into the paper fibers. Some manufacturers have also experimented with polyester laminate or polyethylene coatings for extra barrier protection, though these tend to diminish the “feel” of a genuine paper card.

With all the above qualities optimized, baseball cards printed on specially formulated card stock can realistically be expected to retain their visual integrity, structural soundness, and collectible value for 50 years or longer with average care and storage conditions. This archival capability is a key reason for the format’s enduring popularity among both casual and serious sports memorabilia collectors.

While digital scanning and emerging NFT technologies now allow cards to taken on an additional layer digital preservation, a considerable subset of enthusiasts still prefer the tactile experience and “vintage” aesthetic conferred by physical cardboard. The paper substrate therefore remains an important factor underpinning both the user experience and long-term collecting interests associated with traditional baseball cards.

Sturdy card stock specially tailored for long-lasting print reproduction has been instrumental in enabling baseball cards to serve as cherished mementos, investments, and historical primary sources documenting the development of American professional baseball through both excellent half-century print runs and ongoing secondary markets. The paper remains deeply intertwined with the enduring cultural and financial value propositions presented by these iconic sports collector items.