Six 16oz cups from four suppliers came back in one box last June. Same iced lemon tea, same shelf in a Brisbane cafe, forty minutes each. Three went oval at the base. Two had softened enough that a thumbprint stayed in the side wall. One was straight and still held its lid seal. Not board weight — 3 g/m² of coating and one humid night in a warehouse.
That box is why we condensation-test every cold cup mould before quoting it. Extrusion coating, glue line, rim curl, bottom disc: a swap at any of the four shows up as sweat or a soft base two weeks into a season — at a customer’s counter, not on your dock.
If a buyer asks why the cups sweat, the answer is physics and they usually don’t want it. Here’s the data anyway.
The Test We Run Before Quoting
400g ice plus 150ml water, 22°C room, 65% humidity, weighed every ten minutes for two hours. The cup sits on a paper towel so base weep shows as a ring.
A PE-lined 16oz cup at 15 g/m² inner coating gains 3–5g in the first half hour. Almost all of that is condensation on the outer wall, not leakage. The cup feels wet because it is wet — on the outside. Buyers regularly mistake it for liner failure. At 12 g/m² the same cup gains 6–9g and the base seam darkens by minute 70. At 18 g/m² you get the same 3–5g; what you buy is drying time after the drink is gone, not dryness while it’s full.
| Inner coating | 30-min gain | 120-min gain | Base seam | Typical use |
|---|---|---|---|---|
| PE 12 g/m² | 6–9 g | 11–14 g | Soft at 70 min | Iced water, short pours |
| PE 15 g/m² | 3–5 g | 7–9 g | Firm, slight absorb | Fountain soda, retail |
| PE 18 g/m² | 3–5 g | 6–8 g | Firm | Iced coffee, smoothies |
| PLA 14 g/m² | 4–6 g | 8–11 g | Firm, heat-sensitive | Compostable programs |
Our floor data, plain white 16oz, 100,000-piece lots. Your climate shifts these by a gram or two.
Why Cold Cups Fail Where Hot Cups Don’t
A hot cup has no condensation problem at all. A cold cup sits between a 4°C drink and a 30°C room. The outer wall softens as it absorbs water; the base seam carries drink plus ice on the smallest glued area on the cup; the bottom curl is where water enters first. When a buyer says “the cups leak,” it is the base. Nine times out of ten. We went to 300–320 gsm bottom discs on cold cups, and base returns fell to near zero.
12oz, 16oz, 22oz: Where Each Size Breaks
Taller cups give a hand more leverage, so the 22oz is where cheap board shows up. A full 22oz weighs close to 700g, and a rim curl over 0.3mm out of round makes the lid pop when someone carries it by the top — hence rim gauging every 10,000 pieces.
| Size | Board | Common use | FOB Qingdao / 1,000 | Cups per 40HQ |
|---|---|---|---|---|
| 12oz | 260–280 gsm | Fountain soda, iced tea | USD 33–40 | ~430,000 |
| 16oz | 280–300 gsm | Iced coffee, smoothies | USD 41–49 | ~340,000 |
| 22oz | 300–320 gsm | Cinema, large fountain | USD 52–62 | ~250,000 |
Freight excluded. Print adds 8–15%. Pulp and coating move quarterly — sanity check, not a quote.
PE or PLA: The Honest Price Difference
PE at 15 g/m² is our default. FDA 21 CFR 176.170 and EU 10/2011 compliant, cheap, indifferent to storage temperature, not compostable.
PLA at 14 g/m² costs 22–30% more, roughly USD 9–13 per thousand extra on a 16oz. It composts under EN 13432 and ASTM D6400 only if the finished cup carries the certificate naming the cup, not the film — see our compostable paper cold cups note. Nobody warns you that PLA softens near 55–60°C. A pallet in a Dubai yard in July, or a container on a Texas dock, can warp cups that were perfect in Qingdao. On hot routes ask for heat-stable PLA or ship PE and say so. I’d rather lose the order than field a claim on 200,000 warped cups.
What You Can and Can’t Do About Sweating
A 4°C drink in a 28°C room will sweat. No paper cup stops that without a sleeve. What we control is tolerance: double-side PE adds 1–2 cents per piece and buys maybe 15 minutes before the wall goes floppy, at the cost of repulpability. A lightly sized outer ply keeps the wall stiffer in hand without blocking condensation; dark print only hides the watermark rings.
If customers hold drinks outdoors past 20 minutes, a sleeve or a double wall cup is the answer. Our double wall 12oz comparison has the cost and stack-height trade-off.
MOQ, Lead Time, Shipping
50,000 per size stock white, 100,000 per design custom print. 20–25 days stock, 30–35 with print. Lids ship separately, 1,000 per carton. A 40HQ holds two sizes at 80,000+ each — enough for a distributor to test a 22oz line, not just reorder 12oz.
Shortfalls Worth Knowing
Plain kraft 320 gsm for 22oz is often weeks out of stock. Our tooling stops at 24oz; 32oz goes through a partner plant at double MOQ and 12–18% more. Adding PLA certification to a new mould takes about six weeks; start that paperwork early.
FAQ
Do paper cups for cold drinks need a coating?
Yes. Uncoated paper wicks within minutes and the seam fails. PE at 12–18 g/m² inner is standard; PLA or water-based coatings are the compostable route at a 20–35% premium.
Why do my cold cups feel wet on the outside?
Condensation, not leakage. If the cup stays firm and the base ring is dry, the liner is fine.
Can I use a hot cup for a cold drink?
Short drinks, yes. Past 20 minutes the lighter bottom disc and unsized outer wall let go faster.
How long can a paper cup hold an iced drink?
15 g/m² PE: 6–8 hours before the base seam really softens. 12 g/m²: about 3 hours. 15 is the floor I’d sell.
Is PLA safe for cold cups shipped to hot countries?
Risky. It deforms near 55–60°C and a container roof in summer reaches that. Specify heat-stable grade or ship PE.
What’s the minimum for custom printed cold cups?
100,000 per design, 50,000 stock white. Mixed sizes work in one 40HQ at 80,000+ each.
Getting a Spec That Holds
Send the size, the drink, the climate, and whether you need a compostable claim, and you get a coating spec, a board weight, and a number. Size range is on the paper cup wholesale overview; market details go in the quote form. If your spec won’t survive a Qingdao summer or a Phoenix warehouse, we’ll say so before the deposit.
— Packaging desk, Qingdao
