Postcard Sleeves Compared: Polypropylene vs Polyester vs PVC
Sleeves are the most important supply in postcard collecting. They protect cards from fingerprints, abrasion and each other, and they make it possible to handle a collection without wear. But not all clear plastic is the same. Some sleeves are stable for decades; others can release chemicals that damage the very cards they are meant to protect.
This guide compares the three plastics you will meet most often, explains the labels worth looking for, and helps you pick the right sleeve for each part of a collection. It focuses on sleeves specifically; for boxes, dividers and albums, see our broader postcard storage guide.
The three plastics side by side
| Polypropylene (PP) | Polyester (PET) | PVC (vinyl) | |
|---|---|---|---|
| Archival when uncoated? | Yes, widely accepted | Yes, widely considered the most stable | No |
| Clarity | Good, slightly hazy | Excellent, glass-like | Clear when new |
| Stiffness | Soft to medium | Stiff | Soft and clingy |
| Static | Low | Can be higher; avoid for flaking surfaces | Varies |
| Cost | Lowest of the safe options | Higher | Low |
| Best for | Bulk of a collection | Best cards, RPPCs, display | Nothing in a collection |
Polypropylene: the workhorse
Most postcard sleeves sold to collectors are polypropylene. Uncoated polypropylene is chemically inert enough that conservation suppliers sell it for paper and photographs. It is inexpensive enough to sleeve thousands of cards, flexible enough to slide cards in without catching corners, and has low static.
Its downsides are minor. Thin polypropylene can wrinkle or crease if you pack a box too tightly, and it is not quite as clear as polyester, so scans through the sleeve are a little softer. For most collections, polypropylene is the right default.
Everyday sleeves:
Polypropylene postcard sleeves on AmazonPolyester: the premium option
Polyester film (often sold under trade names such as Mylar) is the material conservators commonly reach for when they want maximum stability and clarity. It is stiffer, so it gives a card more support, and it looks excellent in display. It also costs more, which is why most collectors reserve it for a subset of cards.
One caution: polyester can build up static charge. That is not a problem for an ordinary printed card in good condition, but it is generally advised to avoid static-prone enclosures for anything with a flaking, powdery or friable surface, such as loose glitter, crumbling hand-colouring or damaged emulsion.
Why PVC is a problem
PVC (polyvinyl chloride) is made flexible with plasticizers. Over time those plasticizers can migrate out of the plastic, leaving an oily film, and PVC can degrade and release acidic compounds. The results on paper and photographs can include sticking, staining and damage to images. This is why conservators consistently advise against PVC for long-term storage.
How to spot PVC
- The packaging does not say what the plastic is, or says "vinyl."
- A strong "new shower curtain" smell.
- A soft, clingy, slightly greasy feel, especially in older sleeves and pages.
- Old binder pages and "magnetic" photo albums from past decades. Many contain PVC or harmful adhesives.
If you inherit cards in old vinyl pages or magnetic albums, move them out carefully once you have read our guides to antique postcard albums and handling stuck cards. If a card is firmly stuck, do not force it; ask a paper conservator.
Labels worth looking for
- Material named: polypropylene or polyester (PET). If the material is not named, be cautious.
- "No PVC" or "PVC-free."
- Uncoated. Some films have coatings or additives; plain film is preferred for long-term storage.
- "Acid-free" and "archival." Useful but loosely used in marketing, so prefer brands that state the material too.
- PAT passed. The Photographic Activity Test is an international standard test for storage materials used with photographs. Products that state they passed it are a good choice for real photo postcards.
Getting the size right
Most vintage postcards are close to the standard size of about 3.5 x 5.5 inches. Later chromes and modern cards are often the larger continental size of about 4 x 6 inches. Sleeve makers usually label their products for one or the other, and some offer a slightly larger "deluxe" or oversized fit.
| Your cards | Sleeve to look for | Notes |
|---|---|---|
| Early cards, golden age, white border, linen, most RPPCs | Standard postcard sleeves | Measure a few first; sizes vary slightly between publishers |
| Later chromes and modern cards | Continental sleeves | A standard sleeve will not fit |
| Mixed collection | Both sizes | Do not force standard cards into continental sleeves to save time; they slide around |
| Thick, embossed, or add-on cards | Slightly larger or deluxe sleeves | Avoid pressure on embossing and attachments |
| Oversize, panoramic or fold-outs | Custom or larger sleeves | Do not fold to fit |
Not sure which size your cards are? Measure a few, and compare with listings for the same era:
A good sleeve has a little room on each side so the card slides in without pushing on the corners, but not so much that it shifts freely.
Top-loaders and rigid holders
Rigid holders, sometimes called top-loaders, add stiffness. They are useful for shipping, for a few special cards in a display, and for anything you handle often. They are bulky, so most collectors do not put a whole collection in them. Many people put the card in a soft sleeve first, then into the rigid holder, which reduces scuffing.
How to sleeve cards without damage
- Wash and dry your hands, or wear clean nitrile gloves for real photos and glossy surfaces.
- Work on a clean, flat surface with plenty of room.
- Open the sleeve fully and slide the card in by its edges, short side first. Do not push on a corner.
- Do not force fragile cards. If the card catches, take it out and try a larger sleeve.
- Do not seal with tape. Open-ended sleeves are standard; tape adhesives can damage paper over time.
- Store upright in a box that fits, with dividers, and not packed so tightly that sleeves buckle.
Sleeves are only part of the answer
A sleeve protects from handling and abrasion, but it cannot fix a bad environment. Heat, humidity swings and light do more long-term damage than most handling. Keep cards in a stable, cool, dry interior space, away from attics, basements, exterior walls and direct sunlight. Conservation sources commonly advise moderate, stable relative humidity rather than very damp or very dry conditions; follow the guidance of a reputable conservation organization if you are storing valuable material.
Buying sleeves sensibly
Buy from a supplier that names the material. Buy a small pack first and test the fit on your actual cards, then buy in bulk. If you sell cards, keep a supply of sleeves and rigid holders for shipping; buyers notice. Some collectors also find good-quality supplies through other collectors and dealers' lots.
The bottom line
Verdict: For most collections, uncoated polypropylene sleeves in the right size are the sensible default. Use polyester for your best cards and real photos, avoid static-prone sleeves for flaking surfaces, and get anything out of PVC as soon as you can do so safely.