What causes mtg cards to curl

Overview

Magic: The Gathering (MTG) cards are printed on specialized cardstock, which is a type of thick paper. Like most paper products, this cardstock is susceptible to environmental factors, most notably changes in humidity and temperature. When these environmental conditions fluctuate, the materials that make up the card – the paper fibers, the ink, and any protective coating – can react differently. This differential reaction is the root cause of card curling.

Understanding the Materials

MTG cards are composed of several layers. At their core is a paper pulp, often with a black layer in between to prevent light from shining through (making them opaque). This is then covered with a print layer where the artwork and text are applied, followed by a protective coating, typically a UV-resistant varnish or a similar sealant. Each of these components has a different density and moisture absorption rate.

The Role of Humidity

Humidity is the amount of water vapor present in the air. Paper is hygroscopic, meaning it readily absorbs moisture from its surroundings. When the humidity is high, the paper fibers in the cardstock absorb water and expand. Conversely, when the humidity drops, the paper fibers release this moisture and contract. This expansion and contraction cycle is the main culprit behind card curling.

The problem is exacerbated because the different layers of the card don't absorb and release moisture at the same rate. The ink and coating layers might react differently to moisture changes than the paper core. For instance, if the outer layers absorb moisture more readily or expand/contract more than the inner layers, it can cause the card to warp. This often results in a 'cupping' effect, where the edges of the card lift upwards or downwards, away from the center.

Temperature and Other Environmental Factors

While humidity is the primary driver, temperature also plays a role. Extreme heat can dry out the cardstock, leading to contraction and potential brittleness. Conversely, extreme cold can make the cardstock more susceptible to moisture absorption when it warms up. Direct exposure to sunlight is also detrimental. The UV rays can degrade the paper fibers and fade the ink over time, and the heat generated by sunlight can accelerate the drying process, leading to warping.

Improper storage is a significant contributing factor. Storing cards in damp basements, humid attics, or extremely dry environments (like near a heater) will accelerate the curling process. Being left in a car, especially during hot or cold weather, can also expose cards to rapid and extreme environmental shifts.

Types of Curled Cards

There are generally two types of curling:

• Cupping: This is the most common type, where the edges of the card lift upwards or downwards, creating a concave or convex shape. This is typically caused by uneven moisture absorption across the card's surface.
• Rolling: Less common, this is when the card warps along its length or width, similar to a scroll. This can sometimes be due to the manufacturing process or extreme environmental stress.

Mitigation and Prevention

Preventing card curling largely involves controlling the storage environment:

• Consistent Humidity: Store cards in an area with stable humidity levels, ideally between 40-60%. Using dehumidifiers or humidifiers in your storage area can help.
• Temperature Control: Avoid storing cards in attics, basements, or garages where temperatures fluctuate wildly. A climate-controlled room is best.
• Protection from Light: Keep cards away from direct sunlight and UV light sources. Store them in binders, deck boxes, or sleeves that offer some protection.
• Avoid Pressure: While tightly packed binders can sometimes help keep cards flat, excessive pressure over long periods can damage them. Ensure cards are not being crushed.
• Sleeving: Using card sleeves can offer a minor barrier against minor humidity fluctuations and protect the card surface from scratches and bends.

Can Curled Cards Be Fixed?

Fixing severely curled cards can be difficult and is not always successful. Some collectors attempt to flatten cards by placing them under heavy books for an extended period, sometimes with the help of silica gel packs to absorb residual moisture. Others might try gentle heat application, but this is risky and can easily damage the card further. For minor curling, consistent storage in a stable environment may eventually help the card relax back to a flatter state over time.

It's important to note that even perfectly stored cards can develop a slight curl over time, especially older cards. This is often considered normal wear and tear for a collectible item made of paper.