Half the buyers who write "petal closure" on an enquiry are asking for a valve. They are not going to get one. A petal closure controls nothing — it is a cover, and the difference matters enough that a specification built on the wrong assumption produces a bag that works perfectly and does not do the job it was bought for.
What it actually is
After a discharge spout is tucked up under the bag and tied, something has to protect it for the rest of the journey. A petal closure — sold interchangeably as a star closure or a petal cover — is a set of overlapping fabric flaps sewn beneath the spout. They fold inward over it and are secured, so the spout stays enclosed from the filling line to the discharge station.
The construction detail worth knowing, because it is what you are paying for: a flap is sewn between the spout and the petal closure to hold the spout in position, and a further flap secures the base. The spout does not simply hang inside a bag-shaped pocket.
What it protects against is contamination and abrasion of the product path — which is why it appears on food, feed and pharmaceutical specifications and rarely on aggregate. See food-grade FIBC bulk bags and bulk bags for animal nutrition and feed. India Pack lists Petal (Star) Closure as a secondary bottom closure option on its spout top FIBC.
The terminology problem, and how to write around it
The term is used two different ways in trade literature, and at least one source conflates it with a third device entirely:
| Usage | What it means | Who uses it |
|---|---|---|
| Petal cover | Overlapping fabric flaps sewn under the spout, folded over it as protection | The dominant usage — and the one India Pack's product page matches, listing it beside the Irish closure as a bottom-closure option |
| Petal spout | The spout itself formed in a four-petal shape that closes over the opening when not in use | Appears in Indian glossary sources |
| "Petal" used for an iris closure | A drawstring flow-control sleeve — a genuinely different device | One trade source lists "petal" and "bonnet" as aliases for iris. Do not follow it |
The fix is one line on the RFQ. Do not write "petal closure" and stop — write what you want it to do, then name the device: "protective fabric cover over the tucked discharge spout, secured, with a tie-string closure underneath". A specification that says what the part must do survives a vocabulary mismatch between two factories; one that only names the part does not.
If what you need is graduated flow control, that is the Irish (iris) closure. If you need fast, repeatable, one-handed opening, that is the B-Lock cord lock.
Petal cover, sanitary flap, or neither
| Option | What it covers | Typical reason |
|---|---|---|
| No cover | Tucked spout sits exposed under the bag | Coarse material, single-trip, contamination not a parameter |
| Petal (star) closure | Overlapping flaps fold over the spout | Product-path hygiene; the spout is held in position, not just hidden |
| Sanitary / protection flap | A flap across the whole base of the bag | Protects the base as well as the spout; reduces wear at the bottom |
| Petal closure plus a lock underneath | Cover over a B-Lock or drawcord seal | Contamination control and repeatable one-handed opening |
A petal closure is not a substitute for a closure on the spout itself. It goes over a tie-string, drawcord or cord lock, never instead of one — the single most common error in specifications that name it.
What to send the factory
Which spout the cover applies to; what seals the spout underneath it; whether the bag is lined and how the liner terminates; whether the base also needs a full sanitary flap; the hygiene standard the product path has to meet; and the antistatic type — Type C is conductive and grounded through the bag, Type D is static dissipative and is not. Full family comparison: FIBC spout closures compared. To price it: request a quote.
FAQ
Q: Is a petal closure the same as a star closure? A: Yes. Both names describe the same overlapping fabric flaps folded over a tucked discharge spout. India Pack's product page writes it as "Petal (Star) Closure".
Q: Does a petal closure control discharge? A: No. It is a protective cover, not a valve. Flow is controlled by whatever seals the spout underneath it — a tie-string, a drawcord, a cord lock or an iris drawstring closure.
Q: Do I still need tie-strings if I specify a petal closure? A: Yes. State the spout closure and the cover as two separate lines on the enquiry. A cover over an unspecified tie is half a specification.
Q: What is the difference between a petal closure and a sanitary flap? A: A petal closure encloses the tucked spout. A sanitary or protection flap covers the whole base of the bag, protecting the base from wear as well as keeping the discharge area clean. Some specifications carry both.
Related reading
- FIBC spout closures compared
- B-Lock closure on an FIBC
- The Irish (iris) closure explained
- Spout top with discharge spout FIBC
- Food-grade FIBC bulk bags for food & agriculture
- Request a quote
Sources
- India Pack — Spout top discharge spout FIBC (lists "Irish Closure or Petal (Star) Closure" as a secondary bottom closure) — https://www.indiapack.co.in/products/spout-top-discharge-spout-fibc-bag-supplier-india-35
- FIBC bulk bag 101: types of bag bottom closures explained (star closure and petal cover; sanitary flap protecting the whole bag bottom) — https://blog.nationalbulkbag.com/fibc-bulk-bag-construction/fibc-bulk-bag-101-types-of-bag-bottom-closures-explained
- Jumbo bag terminologies for customers (petal closure defined as a spout formed in a four-petal shape) — https://fibcbigbags.com/fibc-info/jumbobags-terminologies-for-customers.php
- How iris closure FIBCs stop dust and product loss (a trade source listing "petal" and "bonnet" as aliases for the iris closure - cited as evidence of the terminology conflict, not endorsed) — https://epp.vn/news/how-iris-closure-fibcs-stop-dust-and-product-loss/