The outside of a vacuum flask is just steel and paint. What actually decides how your drink tastes, how clean the bottle stays, and how hygienic it is — is the inside. Two finishes dominate the market: the traditional bare stainless interior smoothed by electrolytic polishing (electropolishing), and the premium ceramic-coated interior sprayed over the same stainless body. This is how they really compare — not with marketing words, but with independent SGS test results.
The actual SGS / FDA / LFGB report scans — tap any report to open the full multi-page PDF you can forward straight to your buyers:
The Traditional Way: Electropolished Stainless Interior
Most standard insulated bottles use a bare food-grade 18/8 (304) stainless interior finished by an electrolytic process that smooths and brightens the steel. It is the long-standing, low-cost approach. Its limits are subtle but real: some people taste a faint metallic note (especially with water or coffee), tea and coffee can stain and leave odour over time, and acidic or chloride-rich drinks sit directly against the bare metal. The video below shows that traditional electrolytic interior process.
The Modern Way: Inner Ceramic Spray-Coating
A ceramic interior coating is a food-grade, chemically inert layer that is sprayed onto the inner wall and cured, so the drink rests on a smooth, glass-like ceramic surface and never touches bare metal. That single change drives every advantage below - and unlike a slogan, the performance has been measured in an independent lab. Here's the actual inner ceramic spray-coating process on our line:
The SGS Test Data (Independently Verified)
Jupeng's ceramic-coated interior has been tested by SGS, the world's leading inspection body. These are the actual results we can supply with your order:
| Test | Standard | Result |
|---|---|---|
| Antibacterial - E. coli | JIS Z 2801:2010 | Rate >99.9% (Pass) |
| Antibacterial - S. aureus | JIS Z 2801:2010 | Rate >99.9% (Pass) |
| Food-contact safety (US) | FDA 21 CFR 175.300 - total extractives | Not detected - Pass |
| Primary aromatic amines | EU 1935/2004, (EU) 10/2011 | Pass |
| Lead & cadmium / heavy metals | 84/500/EEC, CM/Res(2013)9 | Pass |
| Overall & specific migration | (EU) 10/2011 / 2020/1245 | Pass |
| Sensory (odour & taste) | EU 1935/2004 | Pass |
The antibacterial numbers are the headline: against both Escherichia coli and Staphylococcus aureus, the ceramic surface achieved a greater-than-99.9% antibacterial rate under the JIS Z 2801 standard (which only requires an activity value of 2.0; the coating measured 6.2 and 5.7). That's a hygiene claim a bare-stainless interior simply cannot make.
Head to Head
| Ceramic-coated interior | Electropolished stainless | |
|---|---|---|
| Taste | Neutral - no metallic note | Good; some detect metal |
| Antibacterial | >99.9% (SGS, E. coli & S. aureus) | Not antibacterial |
| Acidic / flavoured drinks | Ideal - inert surface | Drink contacts bare metal |
| Staining & odour | Resists tea/coffee stain | Can stain over time |
| Cleaning | Smooth, non-porous, wipes clean | Standard |
| Look | Glossy white or coloured | Bright steel |
| Cost | Modest premium | Lowest cost |
On heat retention the two are similar because both keep the vacuum layer - in our own testing a ceramic-lined bottle held 95°C water at about 68°C after 6 hours and 42°C after 24 hours. The ceramic layer doesn't sacrifice insulation; it adds the interior benefits on top.
Which Should a Brand Choose?
If you compete on price in the everyday tier, electropolished stainless is proven and perfectly usable. If you want a differentiated, premium product - one that tastes cleaner, stays more hygienic, and comes with SGS antibacterial and food-safety reports your retailers will love - the ceramic-coated interior is the upgrade buyers can actually taste. Many brands run both: stainless for the value line, ceramic-lined for the hero line.
Jupeng manufactures both electropolished-interior and ceramic-coated interior insulated bottles, in a range of interior colours, from 500 pieces - with SGS, FDA, LFGB and EU reports available. Ask Beyond for a ceramic-lined sample and the test documents, and taste the difference yourself.
Want a ceramic-lined insulated bottle for your brand? Talk to Beyond at Jupeng — factory-direct pricing, SGS / FDA / LFGB / EU test reports on hand, MOQ from 500 pcs, 30-day production. We usually reply within 24 hours.
Explore our 10-model inner-ceramic-coating range — no metal taste, FDA/LFGB certified, MOQ 500, your branding.
View Ceramic Range → Get a QuoteWritten by the Jupeng Drinkware team — Yongkang, Zhejiang, China. Manufacturing drinkware since 1998. Contact Beyond: [email protected] | WhatsApp +86 156 5791 8881