Small jars are the hardest to seal
A 3-litre jar can afford a thick rim and a heavy lid. A 60 ml bottle cannot: the wall is thin, the neck is narrow, and every tenth of a millimetre of rim flatness decides whether the seal holds. Then the bottle is filled on a high-speed line, packed into a carton of sixty, and shipped for weeks — and the failure only appears when the customer opens it.
Small jars fail in three ways: moisture gets in through the thread, the liner takes a set after the first opening, and the cap loosens under vibration in transit. All three come from the same root cause — the seal is a separate part sitting on top of the lid.
What we do differently
The TPE sealing ring is co-injected into the PP lid in the same tool, so lid and gasket are one part. There is no liner to fall out, no gap behind the ring for powder to pack into, and no assembly step that can be skipped on a Monday morning. The sealing lip is moulded flat against a matching rim flatness on the body, which is why a 60 ml bottle passes the same −0.06 MPa vacuum test as a 3-litre jar.
For a pharmaceutical bottle the seal is not a feature — it is the product. Moisture ingress of a fraction of a gram over twelve months is the difference between a batch that passes and a batch that is rejected.
Built for pharmacy and supplements
Effervescent tablets, capsules, powders, granulated herbals and probiotic blends all live or die on moisture control. Our standard build for this segment includes a desiccant-sized headspace, a rim flatness held to ±0.05 mm, and the option of a child-resistant or tamper-evident cap on the same body. Oxygen-sensitive fills can be nitrogen-flushed before capping, and stabilised drug products can be quoted with a light-amber body for UV-sensitive actives.
Where else it fits
- Tablets and capsules — 50–250 ml HDPE or PET bottles, ribbed cap, desiccant headspace.
- Powders and granules — wide-mouth 82 mm option for a scoop, moulded ring keeps fine powder out of the thread.
- Creams and gels — 30–100 ml jars with a sealing disc recess and a flat lid for label wrapping.
- Serums and essences — clear body with a colour-matched ring so the seal reads as part of the design.
- Spices, seeds and samples — small shaker or screw cap on the same 50 ml body, one mould for a whole sample range.
Custom from the mould up
Capacity, diameter, shoulder profile, rim flatness, cap style and colour are all open. A new cavity takes 20–25 days; a colour change on an existing mould takes days. We quote tooling and unit price separately so you can see what you are paying for, and we send first-article samples with the dimensional report before production starts.
Packing & shipping
60 pcs per carton as standard, nested so the sealing lip carries no load. Carton size and pallet plan are confirmed against the exact bottle and cap, and loading photos are sent before dispatch on every shipment.
