Induction seal liner questions, answered
The questions buyers ask us most — how induction sealing works, choosing structures, MOQ, materials, samples and printing. If yours is not here, ask our engineers directly.
What is an induction sealing liner and how does it work?+
An induction sealing liner is a multi-layer membrane that sits inside a cap and hermetically seals a bottle after the filling line. Sealing happens without touching the product: an induction coil above the capper emits an alternating magnetic field, the aluminium foil layer inside the liner heats up, the heat-seal layer melts onto the bottle mouth, and seconds later it cools into a tamper-evident weld.
The result is a seal that blocks oxygen, moisture and leaks, keeps the product fresh, and shows the customer instantly if the pack has been opened.
One-piece vs two-piece induction liners: which should I choose?+
Both are induction liners, but they are built for different caps and different opening experiences:
| One-piece | Two-piece | |
|---|---|---|
| Structure | One fused membrane | Foil membrane + separate backing disc |
| Best for | Plastic screw caps, most liquids | Deeper caps, oils and thicker products |
| After opening | Whole liner comes out with the cap | Foil stays on the bottle, backing stays in the cap |
| Cost | Lower | Slightly higher |
If your cap has enough depth for a one-piece liner, start there — it is the economical default. Two-piece is the safer choice for lubricant and viscous-product bottles.
What is your MOQ for induction seal liners?+
MOQ varies with liner diameter and structure, so we quote it per size. As a rule of thumb, small diameters carry higher piece-count minimums and large industrial diameters lower ones.
Send us your bottle mouth diameter (or the cap neck finish) and we will come back with the exact minimum, unit price tiers and sample options — usually within one working day.
Which bottle materials are compatible — PET, HDPE, PP, PVC, glass?+
Yes — one liner platform, different heat-seal layers matched to each resin:
| PET / PETE | Dedicated PET-seal layer |
|---|---|
| PE (HDPE / LDPE) | EVA heat-seal layer |
| PP | PP-compatible seal layer |
| PVC | PVC-seal layer |
| Glass | Wax-bond / heat-seal structures |
Because seal strength depends on your bottle resin, cap torque and filling temperature, we always validate with sample liners on your own line before volume production.
Do you provide free samples? How long is the lead time?+
Yes. We make structure-validation samples in your diameter free of charge — you only cover the courier cost. Samples let you test the seal on your own filling line before committing to volume.
For mass production, typical lead time is 7 days after order confirmation, and we welcome small trial orders for first runs.
Can you print our logo or anti-counterfeit marks on liners?+
Yes — both. We do surface printing on the sealing layer and steel-stamp embossing, which stays visible on the sealed foil after opening and is widely used on lubricant and agrochemical packs as an anti-counterfeiting feature. Coloured foils are also available.
Minimum print runs apply and depend on the print size and colours. Send us your artwork and target diameter, and we will confirm the print options and minimum quantity for your design.
Why does my fertilizer bottle cap bulge? Do vented liners help?+
Bulging means gas is building up inside the pack. In fertiliser and some agrochemical products, temperature swings and slow reactions release gas; the pressure has nowhere to go, so the cap domes or the seal creeps.
Vented seal liners solve this with a one-way membrane welded into the foil: gas escapes out, but liquid cannot come back through. The pack stays flat and leak-free while remaining sealed. If your product ferments, off-gasses or ships through hot climates, ask us about vented liners.
What sizes of induction liners do you offer?+
We die-cut liners from 9 mm to 182 mm in diameter, covering everything from small vials to large pails, and any custom die-cut shape is possible. Common closure neck finishes — 18, 24, 28, 38, 48, 53, 63, 70, 89 mm and so on — are routine.
Tell us the bottle mouth or neck finish and we cut to match, including odd sizes outside the standard ranges.
Still weighing structures?
Send your bottle mouth diameter, cap type and product. Our engineers will recommend a build-up and post sample liners for your own line test.