Identify the actual opening path
Open production clamshells and mark every route that gives product access: perimeter snap, heat-sealed flange, reusable tab, insert door, or cut edge. The VOID seal must bridge surfaces that separate during the target event. A label near the opening but attached to only one half is decoration, not evidence. If the package can be opened from several sides, determine whether one seal can protect the relevant path or whether structure, multiple seals, or another control is required.
Map the retail peg contact zone
Load a full peg with the actual product weight and spacing. Mark the hang hole, hook shaft, hook tip, label holder, neighboring packs, and the hand paths used for stocking and selection. The first 50 mm below the hang zone may flex heavily on some designs, but geometry varies and must be measured. Watch packs slide forward and backward. Avoid any position where the seal edge repeatedly scrapes the hook, another flange, a divider, or a shopper's thumb.
Give both sides enough bond area
Centering a seal over the seam does not guarantee equal support when one side has a molded ridge or tight radius. Measure the usable flat land on each half and choose a seal width that leaves adequate contact beyond the seam. Rounded corners can reduce picking and snagging. Keep the VOID message within the supported area so activation remains legible. Do not bridge ventilation holes, textured logos, recycle marks, or contaminated molding zones unless the candidate has passed testing there.
Validate the clamshell plastic
PET, rPET, PVC, PP, and other clear packaging plastics can differ in surface energy, additives, texture, recycled content, and treatment. Obtain the actual production lot and apply labels after the normal molding, filling, and cleaning sequence. Inspect wet-out, haze, edge lift, plastic stress, residue, and message contrast. A seal that works on a flat PET sheet may fail on a molded recycled-content flange. Use 5 samples per meaningful material or geometry variant before handling simulation.
Simulate the retail journey
Pack samples in the shipping case, transport or vibrate as the project requires, stock them on the real peg, slide and face them repeatedly, and include customer-like handling. A 25 units pilot across several peg positions shows contact that a single display sample misses. Record premature lift, partial trigger, wrinkles, scratches, and false residue. Then open accepted samples normally and verify clear evidence. The test should include expected temperature and humidity, not only a quiet design-room display.
Create a production placement standard
Use an annotated 1:1 diagram with two measurements from molded features, seal orientation, allowed tolerance, surface preparation, pressure method, and dwell before packing. Approve a first article at each line setup. Inspect seal position, edges, and message before case packing, and code rejects by cause. Revalidate after changes to clamshell resin, mold, flange, hang hole, product weight, case pack, retail fixture, seal, or application equipment. This protects both security evidence and shelf appearance.
Decision table
| Material or substrate route | Cost or price effect | Best-fit use or application scenario | Main risk |
|---|---|---|---|
| Side-seam seal below peg zone | Low application complexity | Clamshells with a flat side flange | Shopper finger contact may still lift an exposed edge |
| Bottom-seam VOID seal | May require package rotation on line | Top-heavy peg packs with severe hang-zone flex | Less visible during shelf inspection |
| Dual side seals | Higher material and labor cost | Packages with more than one practical opening path | More false alarms if placement is inconsistent |
| Structural heat seal plus VOID identifier | Equipment and validation cost | High-risk retail products | VOID label may identify disturbance but not carry the full closure load |
Execution steps
- Map all opening paths and measure the hang hole, peg sweep, flex zone, ribs, curves, and usable flat land on both halves.
- Select candidate positions and seal dimensions, then apply 5 samples per plastic and geometry under production conditions.
- Run a 25 units case-pack, transport, stocking, sliding, facing, handling, and opening simulation on the intended retail fixture.
- Approve a 1:1 placement standard, first-article check, reject codes, and revalidation triggers before rollout.
WowSticker Practical Experience
WowSticker recommends sending filled production clamshells and a photo of the actual peg fixture. State the resin, recycled content if known, molded finish, product weight, opening path, and required residue behavior. A screen begins with 5 samples per variant, followed by a 25 units retail-handling pilot. Record both premature activation and successful opening evidence. The VOID seal should indicate access; it should not be expected to compensate for a weak structural closure or an unsuitable peg design.
Final suitability for Where Should VOID Seals Go on Clamshell Packaging for Retail Pegs depends on the submitted artwork, construction, application evidence, quantity, site, and buyer procedure.
RFQ information to provide
- Clamshell or container size and capacity
- Finished label width and height in mm
- Plastic substrate, resin, recycled content, and surface
- Artwork file format and hidden-message design
- Order quantity and pilot quantity
- VOID transfer type, adhesive, and finish
- Destination country and retail fixture
- Water, humidity, heat, chemical, and rub exposure
- Required delivery time and launch timeline
- Target price range or packaging budget
- Product weight, hang-hole geometry, peg spacing, and opening route
Frequently asked questions
Why avoid the hang hole?
The peg and repeated sliding create flex, scraping, and concentrated contact that can lift or falsely trigger a seal.
Can the seal hold the clamshell closed?
It should primarily provide tamper evidence; the package needs an adequate structural closure of its own.
How much of the seal should bond on each side?
Use enough validated flat contact area on both halves for the selected construction; test the actual geometry rather than applying a universal ratio.
Does clear PET guarantee good adhesion?
No. Resin, additives, recycled content, treatment, molding texture, contamination, curvature, and dwell all affect results.
What should a peg test include?
Include case packing, transport, stocking, repeated sliding, facing, customer-like handling, environmental exposure, and final opening.
When must placement be retested?
Retest after changes to resin, mold, flange, hang hole, weight, fixture, case pack, seal, or application process.
Review WowSticker product options or submit controlled project details through wowsti.com.