Buyer guide
How to choose a PET preform for your bottle
Choose a PET preform by what you will fill, then by the neck finish your cap fits, then by weight and colour. This guide is for anyone starting or expanding bottle making.
Updated
A preform is injection moulded, then your blow moulding line reheats it and stretch-blows it into a bottle mould.
This is the two-stage process. Stage one is injection moulding. Nawkiran does this at its plant in Baidyabati, West Bengal, and supplies the preform.
Stage two is stretch blow moulding, on your own line. The line reheats the preform, stretches it and blows it out against the walls of the bottle mould.
Blowing does not change the neck finish. The neck of the preform is the neck of the bottle, so the finish you buy is the finish your cap must fit.
Pick the family by the product in the bottle: water and beverages, carbonated drinks, oil and liquor, wide-mouth food, or refillable fridge bottles.
Packaged drinking water and general beverages
Use 3 Start/Alaska, the catalogue range for packaged drinking water and general beverage bottles. Neck finishes: 26/22 mm and 28 mm. Weights: 7.1–33.1 g.
Carbonated soft drinks
Use PCO 1810 or PCO 1881, both 28 mm finishes. The catalogue lists 1810 PCO for pressure-rated CSD and carbonated beverage bottles, and 1881 PCO for modern lightweight carbonated bottles. PCO 1810 weights: 13.5–31 g. PCO 1881 weights: 10.5–52 g.
Edible oil, liquor and pharma with aluminium roll-on caps
Use ROPP (Roll-On Pilfer-Proof), the finish made for aluminium roll-on caps. Neck finishes: 25 mm and 28 mm. Weights: 10.5–30 g.
Wide-mouth jars for food, confectionery and FMCG
Use Jar, the catalogue range for confectionery, dry-food, pharma and FMCG jars. It has the widest mouths in the catalogue. Neck finishes: 7, spanning 38–120 mm. Weights: 5.5–101.5 g.
Refillable fridge and dispenser bottles
Use Fridge Bottle, the catalogue range for reusable fridge and water-dispenser bottles. Neck finishes: 4, spanning 29–46 mm. Weights: 25–55 g.
Buy caps and preforms made for the same neck finish, because a closure is made for one specific finish.
Check the finish name on your caps before you choose a family. The millimetre size alone is not enough: the catalogue lists a 28 mm neck under 4 families: 3 Start/Alaska, PCO 1810, PCO 1881 and ROPP.
If you already run a capping line, keep the finish of the caps you use today. If you are starting from scratch, choose the finish first and then buy caps for it.
Carbonated drinks have two 28 mm choices, PCO 1810 and PCO 1881. Their caps are not interchangeable.
A heavier preform gives a bigger or stronger bottle, and your blow-mould maker or bottle design sets the exact weight.
Nawkiran lists weights in grams for every neck finish. These are the catalogue ranges by family.
- 3 Start/Alaska: 7.1–33.1 g
- PCO 1810: 13.5–31 g
- PCO 1881: 10.5–52 g
- Jar: 5.5–101.5 g
- Fridge Bottle: 25–55 g
- ROPP: 10.5–30 g
Preforms come clear (natural) or tinted, and you choose the colour in your enquiry.
Nawkiran has supplied green, blue, pink, yellow, violet, amber, orange and red tinted preforms. Clear means no tint is added.
Name the colour you want when you send the enquiry.
Nawkiran has made hot-fill versions of some preforms, so ask when you enquire.
Say in your enquiry that you need hot-fill, with the family, neck finish and weight you have in mind.
Send the preform family, neck finish, weight, colour, order quantity in kilograms, and your city and state.
Send these on WhatsApp and Nawkiran replies with a quote.
- Family: 3 Start/Alaska, PCO 1810, PCO 1881, Jar, Fridge Bottle or ROPP.
- Neck finish: as the catalogue lists it, for example 28 mm.
- Weight: in grams, from the size chart.
- Colour: clear, or the tint you want.
- Order quantity: in kilograms.
- City and state.
These are the 8 terms used in preform catalogues and in this guide.
- Preform
- A small PET piece made by injection moulding. A blow moulding line reheats it and stretch-blows it into a bottle or jar.
- Neck finish
- The shape of a preform's mouth: its opening, thread and support ring. A cap fits one finish only. The catalogue gives it in millimetres.
- Support ring
- The ring around the neck, below the thread. Machines hold and carry the preform and the bottle by it.
- PCO
- Plastic closure only. A group of neck finishes made for plastic caps. PCO 1810 and PCO 1881 are the two PCO finishes in the catalogue, both 28 mm, for carbonated drinks.
- ROPP
- Roll-On Pilfer-Proof. A neck finish made for aluminium roll-on caps, used for edible oil, liquor and pharma bottles.
- 3-start thread
- A thread that begins at three points around the neck, so three threads run side by side. 3 Start/Alaska is the catalogue family named after it.
- Stretch blow moulding
- The second stage of making a bottle. The preform is reheated, stretched with a rod and blown with air into a bottle mould.
- rPET
- Recycled PET. Nawkiran is developing rPET-ready options for customers who want to reduce virgin-resin use. Final performance, compliance, colour and pricing depend on the application and resin mix.