Part of our series on mason jars wholesale — read the overview first if the format is new to you.
Bulk mason jar lids come in two standard sizes: 70 mm for regular-mouth jars and 86 mm for wide-mouth jars. Before asking for a quote, fix three things: the mouth size, the construction (two-piece disc and band, or a one-piece cap), and the plastisol grade that matches your thermal process. The lid, not the glass, is what holds the vacuum through a shelf life of 24 months or more, so it should be specified before the jar drawing is frozen.
70 mm regular mouth and 86 mm wide mouth compared
Both figures describe the outside diameter of the sealing surface on the jar. The standard is tight enough that a well-made 70 mm lid seals on any correctly made 70 mm jar. Regular mouth runs from 4 oz jelly jars up to 1 quart; wide mouth is the usual choice for the 16 oz, 24 oz, and 32 oz jars used for pickles, salsas, and meal-prep products.
| Specification | 70 mm regular mouth | 86 mm wide mouth |
|---|---|---|
| Outside diameter of sealing surface | 70 mm | 86 mm |
| Usual jar capacities | 4 oz to 32 oz | 16 oz to 64 oz |
| Tinplate thickness of the flat lid | 0.15 mm to 0.18 mm | 0.15 mm to 0.20 mm |
| Plastisol compound weight | approx. 0.9 g | approx. 1.4 g |
| Typical products | Jams, sauces, juices | Pickles, salsas, whole vegetables |
The choice reaches beyond appearance. It sets the capping equipment you need and the lid stock you carry. Regular-mouth jars tend to behave better on older cappers, and their lids are more widely stocked. Specialty finishes such as 63 mm and 58 mm serve hex jars and economy formats, but the two main sizes usually make up more than 85% of a buyer's closure consumption in a year.
Two-piece lids or one-piece caps
Pick the construction from the process, then discuss cost.
Two-piece disc and band
The traditional closure is a flat tinplate disc carrying a ring of plastisol, plus a separate threaded band. In the retort or water bath the band presses the disc onto the glass while air escapes. Once the jar cools, vacuum holds the disc by itself, so the band can stay on for shelf presentation or come off for shipping.
The disc is a single-use sealing part, which means every fill gets a fresh gasket; the band is a reusable mechanical part. For products that are truly heat-processed at 100°C to 121°C, including shelf-stable low-acid and acidified foods, this is the safest and most widely accepted system and the one we suggest.
One-piece caps
Here the thread and the sealing surface are a single stamped or moulded part. Polypropylene versions resist rust, go through the dishwasher, and can take a foam or induction liner in place of plastisol. They suit refrigerated products, dry goods, fermentation and household reuse.
Metal one-piece continuous-thread caps, deep-drawn with a plastisol gasket, cope with a hot-fill-hold product such as pasta sauce filled at 85°C to 90°C.
Continuous thread and lug finishes are not interchangeable
A continuous-thread (CT) cap has one unbroken helical thread and needs a full 360 degrees or more of rotation to apply. A lug cap carries three, four, or six short lugs on its skirt that catch interrupted lugs on the jar and close with a quarter turn of about 60 to 90 degrees.
Lug closures apply faster on rotary cappers and give steadier torque, so they are the usual choice for high-speed commercial canning. CT is the norm on home-canning-style mason jars and in smaller runs. A lug cap cannot seal on a CT finish however hard it is forced, and because the glass finish is moulded differently for each, the closure system has to be chosen before the jar drawing is final.
CT mason lids follow the 70 mm and 86 mm standards above. The lug and twist-off cap formats run from 38 mm through 82 mm, with pasteurization-grade and retort-grade plastisol. If you are still weighing lug, CT, crown and cork, our guide to choosing a closure for a glass container matches each family to the finishes and thermal processes it suits; it is worth reading before a first sampling round.
How the plastisol seal and vacuum button work
The seal is formed by heat and air pressure, not by how tightly the band is screwed down. Plastisol is a PVC-based compound laid into the groove at the edge of the electrolytic tinplate disc. In processing it softens and flows into the tiny irregularities of the glass sealing surface. As the jar cools, vapour in the headspace condenses and internal pressure falls. Atmospheric pressure, roughly 101 kPa, then presses the disc into the gasket, which sets in the shape of that particular jar.
Compound quality therefore outweighs every other lid variable. If the plasticizer content is inconsistent, the compound either fails to flow at process temperature or migrates into the food across a 24-month shelf life.
The raised circle at the centre of the disc is the vacuum button. A good seal pulls it down with a click, and it rests roughly 3 mm to 5 mm below its unsealed position. A button that has popped back up means lost vacuum, and the jar is rejected wherever that is found: on the line, in the warehouse or on the shelf. It gives a co-packer and a retailer the same tool-free pass or fail check.
A button formed to flip at approximately 25 kPa to 35 kPa below ambient is sensitive enough to reveal a marginal seal, yet it will not give false failures from normal handling or altitude changes up to 1,500 m.
Matching lid tolerances to the jar finish
The jar finish and the lid each have a tolerance band, and a seal needs the two to overlap. On a 70 mm finish the critical dimensions are the sealing surface diameter, held to plus or minus 0.3 mm, the thread lead angle, and the glass thickness under the gasket.
Put a jar from the tight end of its range under a lid from the loose end and the interference can crack glass at capping. Reverse the pairing and the closure feels tight but loses vacuum within 72 hours. Each part passes its own supplier's inspection; the pair fails, and nobody sees it until filled goods are in distribution.
Sourcing jar and lid together is the dependable fix, which is why we check the closure against the mason jar specification from the first drawing. Buyers who split supply should, as a minimum, obtain finish drawings from both suppliers, confirm that both cite the same tolerance standard, and run a 500-unit pilot fill before committing to a full container.
Tests to write into the purchase specification
An order with no test criteria invites disputes. These checks belong in the specification itself:
- Seal integrity. Test lids go onto jars, through your actual thermal cycle, then sit at 37°C for 14 days. Vacuum retention, button position and gasket adhesion are checked afterwards.
- Torque. Application and removal torque are read on a calibrated meter against an acceptance window that depends on diameter.
- Migration and food contact. This is the check most often skipped. Plastisol compounds must meet FDA 21 CFR 175.300 for resinous and polymeric coatings and, for Europe, EU Framework Regulation 1935/2004. An overall migration limit of 10 mg per square decimeter applies.
- Corrosion. High-acid fills such as pickles at pH below 4.0 need an enamel system rated for acid contact. A 48-hour acid-resistance test on lids drawn from each lot guards against rust-spot complaints six months into shelf life.
What sets the price and how to plan supply
Lid cost follows three things: tinplate, order volume and decoration. Tinplate is a commodity, so quotations move with the steel index. Figures are worked out per project.
Closures run best as a programme, not as a string of spot orders. That means one annual specification covering dimensions, tinplate grade, compound type, print artwork and test criteria, a rolling forecast so tinplate can be reserved ahead, and a line audit once a year, in person or by video.
The lid should also be considered with every jar decision. When a brief calls for canning jars in amber or green glass, we check that the enamel and print colours of the lid are specified to suit the glass, since a clashing closure undoes the effect the coloured jar was chosen for.
To start or re-qualify a closure, send a jar drawing or a physical jar, the thermal process with temperature and hold time, and an estimate of annual volume.
Frequently asked questions
What is the minimum order for bulk mason jar lids?
It is quoted per project. The lid size, the tooling, any printing and the quantity all shape the answer.
Will standard lids fit jars from another glass maker?
Standard 70 mm and 86 mm CT lids are dimensionally standardized, so they fit most jars built to the same finish specification. Fitting is not proof of sealing, though. Glass plants hold slightly different tolerances on the sealing surface and thread profile, so validate the pair with a trial fill.
How do pasteurization-grade and retort-grade lids differ?
In the plastisol compound and the enamel. Pasteurization grade uses a standard compound for processes up to about 100°C, such as water-bath canning of jams and pickles. Retort grade is formulated to survive 121°C for hold times of 60 to 90 minutes without softening too far or losing adhesion afterwards, and it carries an enamel rated for that stress. A pasteurization lid in a retort is a frequent cause of failed seals, so state the whole thermal cycle in your enquiry.
Can flat lids and bands be printed or embossed?
Yes. Flat lids take lithographic printing in up to 6 colors. Bands can be lacquered in a custom colour or embossed with a brand name. Print always goes on the outside, over a base enamel; the inside keeps a food-grade lacquer and the plastisol gasket.
How should bulk lids be stored, and for how long?
Keep them in the sealed original cartons in a dry warehouse between 10°C and 30°C, out of direct sunlight and away from chemical vapours. The disc and band stay stable for years. The gasket performs best in its first 24 months, so check the date code on the carton and rotate stock first in, first out. Long spells above 70% relative humidity can start corrosion under the enamel edges before the lids ever reach the line.
What documents should come with a shipment?
Ask for a certificate of analysis for the lot, covering dimensional inspection, torque data and seal-test results, together with a declaration of conformity to FDA 21 CFR 175.300 and EU 1935/2004 for the plastisol compound. Third-party migration reports should be no older than 6 months.
Are plastic mason jar lids suitable for real canning?
No. Most one-piece plastic lids with foam liners are rated for hot fills up to about 85°C, not for water-bath or retort cycles, and a foam liner does not form the hermetic vacuum seal that plastisol does. A product that must stay shelf-stable at ambient temperature for 12 to 24 months needs a metal closure. For refrigerated or dry products, plastic lids are durable and easy for consumers to live with.