By Crossave · Updated: August 2026
As with trading cards (see the dedicated guide), well-chosen comics and manga can lose value quickly if they are stored badly — and buying from abroad adds risk, because the item has travelled further in packaging you did not choose. This guide covers what to do as soon as it arrives.
Mylar (archival polyester) offers a gas barrier roughly 350 times better than ordinary polyethylene and is rated by manufacturers to last up to 150 years without replacement — the trade-off is the higher cost, and the fact that it does not reseal as neatly as an ordinary bag. Polypropylene is cheaper and more practical for everyday use, but should be replaced roughly every 5-10 years and tends to crease over time. The rule of thumb most specialist dealers use: Mylar for anything worth more than $30-50, polypropylene for the rest.
Current/Modern comics use bags of 6⅞ x 10½ inches (about 17.5 x 26.7 cm), slightly narrower than Silver Age ones (7⅛ x 10½ inches, about 18.1 x 26.7 cm) — a small difference, but enough to leave an issue either cramped or loose in the wrong bag. For thicker issues there are "thick" versions of the same eras (7 x 10½ for Current, 7⅝ x 10½ for Silver Age): the era and the thickness are two separate choices, not one. Backing boards follow the same logic with slightly different measurements between "regular" and "current" formats — it is worth checking the stated size before buying a box of bags rather than trusting that one size fits everything.
Unlike a bag, a manga's obi (see the first-print guide) should not be removed to "protect it better" separately: specialist dealers recommend keeping it on the volume, storing everything upright in a cool, dry place, and handling it as little as possible. For graded copies the obi stays sealed inside the slab together with the volume, so the question no longer arises after certification.
One risk shared by comics, manga and trading cards: PVC bags — cheaper, and sometimes used by less careful sellers — release plasticisers over time that slowly damage paper and ink. The same independent study cited in the Pokémon storage guide applies equally here: if a comic or a manga arrives in a bag you are not sure about, re-bag it straight away in a genuinely archival one.
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