CollectionPlnr

Comic Bags and Boards Explained

By Alexis Pratsides, FounderUpdated

The Function of a Bag and Board

A comic bag has two jobs: seal the book away from airborne dust, humidity and contaminants, and provide a clear window that lets you identify the issue without touching it. A board keeps the comic rigid so it does not develop spine stress creases or corner bends during storage. Together, a bag and board form the minimum viable protection for any comic you care about keeping in collectible condition.

Choosing the wrong bag or board does real damage. PVC bags chemically attack ink. Acidic boards stain pages. Undersized boards buckle the cover. None of these problems are visible on the day you bag the book - they show up three years later when you pull it out for resale and find the pages have yellowed or a tide mark has appeared along the bottom.

Bag Materials: A Comparison

PVC (Polyvinyl Chloride) - Avoid

PVC bags are the enemy. They look like regular comic bags but emit hydrogen chloride gas as they degrade, which reacts with the moisture in paper and forms hydrochloric acid. This yellows pages, softens ink and creates a characteristic chemical smell. PVC bags are still sold in some general retail stores. How to spot them: they feel slightly tacky, smell faintly of plastic, and cost significantly less than archival alternatives. If a bag has no archival or acid-free labelling, assume it is PVC and avoid it.

Polyethylene (PE)

Polyethylene is a safe, acid-free material that represents the entry level of archival-quality bagging. PE bags are slightly hazy and soft to the touch. They are fine for books you read regularly or rotate through frequently, as they are inexpensive and easy to open and reseal. The practical limit is longevity: PE becomes cloudy and brittle after 10-15 years, so valuable books need re-bagging on a cycle. Most "economy" archival bags sold in packs of 100 are polyethylene.

Polypropylene (PP)

Polypropylene bags are crisper, clearer, and more durable than PE. They are the most popular choice in the hobby because they strike the right balance between protection, visibility and cost. PP bags maintain their clarity and flexibility for around 20 years. The reseal flap tends to be sturdier than on PE bags. If you are bagging a modern collection of thousands of books, polypropylene is the right default material.

Mylar (Biaxially Oriented Polyester)

Mylar is the archival gold standard, originally developed by DuPont for military use. It is chemically inert, extremely strong, and rated for over 100 years of stable storage. Mylar D (the most common variant) is used by CGC for their own internal storage. The cost is substantially higher - expect to pay 10-15 times the per-bag cost of polypropylene. Use Mylar for key issues, Golden and Silver Age books, or any book whose value justifies the investment. E. Gerber (the original manufacturer), BCW and Bags Unlimited all sell genuine Mylar bags. Beware of imitations labelled "Mylar-type" or "polyester" without specifying the grade.

Sizing Reference

Using the wrong size bag does as much damage as using the wrong material.

  • Current/Modern (1980 to present) - 6.875 x 10.5 inches with board, 6.75 x 10.5 without. The most common size. Fits the vast majority of comics published in the last 45 years.
  • Silver Age (roughly 1956-1979) - 7.25 x 10.5 inches. Older comics are taller and wider. If a current bag crinkles the top edges of your comic, you need Silver Age sizing.
  • Golden Age (pre-1956) - 7.75 x 10.5 inches. The largest standard size. Golden Age books are rare enough that you should double-check the exact dimensions before ordering bags in bulk.
  • Magazine/Treasury - oversized format for publications like Heavy Metal, Savage Sword of Conan, and Treasury editions of DC and Marvel.

Boards: What to Look For

Acid-Free vs Buffered vs Lignin-Free

These three terms appear on board packaging and each means something different.

  • Acid-free means the board has a neutral or near-neutral pH (7.0 or above). Acidic boards will stain comic pages brown over years. This is the minimum requirement for any board used in archival storage.
  • Buffered means the board contains an alkaline reserve (usually calcium carbonate) that actively neutralises acids that migrate from the comic's own paper or the environment. This is better than simply acid-free, especially for older books printed on acidic pulp paper.
  • Lignin-free means the natural wood lignin (which breaks down into acids over time) has been removed from the pulp. For long-term storage, lignin-free boards are meaningfully better than boards that are merely acid-free.

For maximum protection, use boards that are all three: acid-free, buffered, and lignin-free. The best-known brands (BCW, E. Gerber, Bags Unlimited) all offer boards meeting this standard.

Board Thickness

Standard boards are around 24-point (0.024 inches) thick. Thicker boards (42-point) offer more rigidity for oversized or heavy books. Thinner boards save a little money but provide less structural support. For most modern comics, 24-point is sufficient.

How Often to Replace Boards

Even high-quality boards absorb acids over time. For valuable books, replace boards every 3-5 years. When replacing, inspect the board - if it has yellowed or developed any smell, replace immediately. Store spare boards flat in a sealed plastic bag to prevent them absorbing moisture before use.

The Right Way to Bag and Board a Comic

  1. Lay the board flat. Place the comic face-down on the board so the back cover faces you.
  2. Slide both together into the bag, board first, with the open end of the bag at the top.
  3. Fold the flap over (or remove and reseal if the bag uses a tape strip).
  4. Check that the comic sits snugly - no bowing, no exposed edges, not crammed in tight.

Some collectors prefer to place the board behind the comic (between comic and back of bag) rather than inside. Either method works. What matters is that the board is in contact with the full back cover to provide support across the entire surface area.

Reseal Flaps and Tape

Most polypropylene bags come with a self-adhesive reseal flap. Use it. An open-top bag allows dust and moisture to enter over time. If you need to re-open a bag regularly, use a small piece of repositionable tape rather than the reseal adhesive, which can dry out and stop sealing properly after repeated openings.

Buying Bags and Boards in Bulk

For collections of more than a few hundred comics, buying bags and boards in bulk is significantly more cost-effective than buying in small packs. Standard pack sizes are 100 bags and 100 boards per pack. Most suppliers offer price breaks at 1,000 units. Reputable suppliers include BCW Supplies, E. Gerber, Bags Unlimited, and Comic Guard. All sell both polypropylene and Mylar bags alongside archival boards.

When buying in bulk, order a small test pack first to check fit against your comics before committing to 1,000 units. Bags in the same size category can vary by a few millimetres between suppliers, and a bag that is slightly too wide allows the comic to shift and potentially fold during storage.

Long-Term Archival vs Active Collection Storage

Not every comic in a collection needs the same level of protection. A useful way to think about a collection is to divide it into three tiers by how you engage with it.

  • Active reading copies - books you read, lend, or handle regularly. Polyethylene bags and standard boards are fine. Keep in short boxes for easy access.
  • Stored collection - books you keep but rarely touch. Polypropylene bags and buffered boards in short or long boxes in a stable environment.
  • Archival key issues - first appearances, high-value books, anything you might submit for grading. Mylar bags, premium buffered lignin-free boards, stored in a climate-controlled space. These books get the full treatment.

Applying Mylar protection to every comic in a 5,000-issue collection is unnecessary and expensive. Applying polypropylene to a Golden Age key issue is under-serving a potentially valuable asset. Matching protection tier to book importance is the practical approach that most serious collectors use.

Once your collection is bagged and boarded correctly, the next decision is how to store the boxes themselves. See the full guide to how to store comic books for environment and box recommendations. You can log and value every issue in your collection at CollectionPlnr Comics.