Start with the rule that settles a good share of these holders: a semi-rigid going in for grading goes out bare. Nothing on the plastic, number on the mailer instead. That leaves two cases: holders you ship to buyers, and holders in your own stock.
A semi-rigid is a transport vessel. It flexes in your hand, the top half-inch flares open on purpose, and the card is meant to come back out at the other end. That is three reasons a Serial Seal™ behaves differently here than on a rigid top loader. The seal is one die-cut size either way, so everything below is about placement.
What you are actually sealing
A Card Saver I from Cardboard Gold measures 3-5/16" x 4-7/8" — 3.3125" x 4.875", or 84.1 x 123.8 mm. Those figures come from retailer listings and packaging copy, not from a published spec. Card Saver II, III and IV exist at other sizes; we will not quote numbers we could not confirm, so measure yours if it is not a CS1.
The material is 9 mil crystal-clear plastic, so a loaded edge is roughly 0.018" of wall plus the card — call it 0.04" to 0.06". It springs rather than sitting rigid, which matters below.
The top 1/2" is a deliberately flared lip. It bows outward so the card goes in top-first without catching a corner. That lip is the point of the design, and it is not flat. Nothing you stick across it stays stuck.
Where the seal goes
Use a FOLD, over a long side edge. Not the top.
The seal is 0.75" x 1.77" die-cut. Wrapping it over an edge does not hand you half of 1.77" per face — the edge eats part of the length. Landing per face is (1.77 - T) / 2, where T is the thickness of the edge you are wrapping. On a loaded Card Saver, T is about 0.05":
(1.77 - 0.05) / 2 = 0.86" of landing on each face.
That is 26% across the holder's 3.3125" width, and the seal's 0.75" covers 15.4% of the 4.875" side edge.
In our own handling, a fold starts feeling loose below roughly 0.55 to 0.58 inches of landing per face. That is what the bench has taught us, not a published spec — wrap one on your own holder and pull at it before committing to a placement. At 0.86" there is margin either way.
Place it at mid-height of the side, at least an inch below the lip, so the fold sits on flat parallel walls.
| Placement | Landing per face | Verdict |
|---|---|---|
| Fold over a long side edge (4.875") | 0.86" | Use this. Flat parallel walls on both sides. |
| Fold over the top edge, below the lip | 0.86", but the lip eats 0.5" of it | Over half the face contact lands on flared plastic that does not touch. Skip it. |
| Fold across the lip itself | Effectively none | The two halves spring apart. It tents and self-peels. |
| Single, flat on one face | 0.75" x 1.77" flat | For inventory marking. It crosses no opening. |
When a single makes more sense
If the holder is not going anywhere — stock in a box, or show inventory numbered against a list — a SINGLE on the back face is the better call. You are not bridging an opening, you are giving the holder a number that matches a row in your record. Lay it flat, clear of the card window, and log it.
You need not decide the split in advance. Folds and singles come off the same run, and the sequence does not care which pile a number lands in — you sort that at the bench, as each holder ships or goes back in the box. On the builder that is one quantity for both piles, not two orders.
Step by step
- Load the card and seat it fully. Always first. Once a fold is on, working the card past it is how corners get dinged.
- Decide fold or single. Going out to a buyer: fold. Sitting in inventory: single.
- Wipe the holder with a dry microfibre. Semi-rigid plastic picks up finger oil off the shelf and adhesive hates it.
- Pick your edge — a long side, mid-height, at least 1" below the lip. Mark it with a fingernail to keep a batch consistent.
- Peel the liner and land the seal on one face first, held square. Placing both faces at once gives you a skewed wrap.
- Roll it over the edge with a thumb and press the second face down, burnishing outward from the fold so no air is trapped.
- Photograph it. One dated shot, serial legible, card visible in the same frame.
- Write the number against the order or the inventory row before you do anything else. A serial you did not record is a decoration.
A holder going out for grading goes out bare
We do not seal semi-rigids that are being submitted. Graders publish their own requirements and revise them, so check the current instructions from whoever you are sending to. Our rule does not depend on knowing them: assume anything applied to a submission holder comes off at the other end, with your card inside it, on a holder that gets discarded there anyway.
Put the number on the outer package instead. Sealing a shipping package covers where a fold goes on a mailer flap.
The standing rule does not bend: never put adhesive on the card itself. Seal the holder, the bag, the box or the package. A Card Saver's opening is at the top, so keeping the seal down the side keeps it well away from a card edge.
What the seal is
A seal does not prove a card is real, does not prove a holder was never opened, and does not authenticate anything. It is thin printed film with adhesive and a number on it.
Someone can take the seal off a Card Saver and put a different one on. With this format they need not bother — the holder is cheap and the card slides straight out of the top, so a fresh holder and a fresh seal is the easier route. The stock is thin holographic vinyl on permanent adhesive and tears rather than lifting in one piece, which matters only in that changing your mind means replacing the holder. None of it changes what the product does.
What it does is carry a number. You chose the prefix and the starting number, we printed the run sequentially, and no two seals in your order share one. The number is worth something because you photographed it on this holder on this day and wrote it down against the order. Skip that and you have a decoration.
If your layout carries the VOID IF DAMAGED line, what that line is and is not is covered there rather than on every format page.
How many do you need
A good slice of what passes through your hands here takes no seal at all: submissions ship bare, so every holder headed to a grader counts as zero. Subtract that pile; two are left, and only one is a running cost.
Holders going out to buyers take one fold per holder per journey — three cards to one buyer in three Card Savers is three folds, and a holder that returns from a grader and later ships is a second fold, not a reuse.
The shelf is a one-off. Every holder in the box gets a single, gets written into your list, and never gets renumbered. Two hundred on the shelf is two hundred seals, once, and then that line reads zero — a first-order cost, not a monthly one.
So it is one addition: the shelf as it stands, plus outgoing holders per month times the months covered. A shelf of 200 with fifteen a week going out — 65 a month, 780 across a year — is about 980, and that sits past the 600 rung, so the whole run is 40c each — 984 seals, the next whole twelve, is $393.60. Smaller bench: 60 on the shelf and four a week is a bit over 260 a year — 300 seals is $135.00, 45c each. Between them, 600 is $240.00 at 40c.
Sixty seals is the minimum order, $30.00 at the 50c list rate, so a bench that lands under that buys sixty anyway.
The rate applies per order, one tier at a time, so a year's count bought at once sits on a lower rung than the same count split across the year. No code to enter; the tier lands at checkout.
Common mistakes
- Sealing across the flared lip. The lip springs outward and the body does not. The seal tents, lifts within a day or two, and you end up doing it twice.
- Sealing a holder that is being submitted. Send it bare and put the number on the mailer.
- Sealing before the card is fully seated. Once the top is bridged, getting the card in or out means flexing it past the seal.
- Placing the seal where the holder flexes most. Repeated flex under an adhesive patch crazes 9 mil plastic. Mid-height on a side edge flexes far less than a corner.
- Sealing the holder when the real question is the package. What arrives at the buyer's door is a mailer problem.
Questions people ask
Can I put a seal on a Card Saver I am submitting for grading?
We do not. Check the current instructions from the company you are sending to — they set their own and revise them. Either way, assume anything on the holder comes off there, with your card inside it. Seal the mailer instead.
Should I seal the top edge or the side?
Side. A seal across the flared top sits on two surfaces that separate. A fold over a long side edge lands (1.77 - T) / 2 per face — about 0.86" on a loaded holder — on flat parallel walls.
Is a top loader a better thing to seal than a Card Saver?
For a card that is staying put through a sale, yes. A top loader is rigid, flat and cheap, the card never sits near adhesive, and one seal size covers every point thickness. Semi-rigids are a transport format — seal one for the journey, not for storage.
Ordering
60 Serial Seal™ minimum · From $30.00 · As low as $0.30 each in bulk.
Numbered holographic vinyl, twelve seals to a pack — $6.00 a pack at list. Sixty is the smallest order — $30.00, 50c a seal, a rate that holds until 120; 120 drops to 45c ($54.00), 600 to 40c, 1,200 to 36c, 2,400 to 33c and 4,200 to 30c, the floor for every run above it, applied at checkout with no code. Self-serve runs top out at 10,008 ($3,002.40); bigger runs we quote rather than post — ask us. No setup, die, or design fees. Commercial license and copyright included. Take a gallery design on the builder, or run your own logo through add a logo. Ship more than one format? The map.
Serial Seal is an independent printer. We are not affiliated with, endorsed by or sponsored by PSA, Beckett, CGC, SGC, Ultra Pro, BCW, Cardboard Gold, eBay, Whatnot, TCGplayer or any card manufacturer. Brand names are used only to describe the products they make. Nothing here is legal advice.