What it is
Pre-painted galvanized iron (PPGI) is GI or GL coil coated with a paint system (polyester, PVDF) for finished roofing, cladding, and appliance panels. Two hidden specs stack here — the zinc/aluminum-zinc substrate coating AND the paint film thickness — giving suppliers two layers to shortchange.
Grades & standards buyers order
| Grade | Standard | Notes |
|---|---|---|
| PPGI (zinc substrate) | EN 10169 | Painted over hot-dip galvanized base. |
| PPGL (Al-Zn substrate) | EN 10169 | Painted over aluzinc; better corrosion but often confused with PPGI. |
| Paint: RMP / PVDF | — | PVDF lasts far longer outdoors than cheaper polyester; a common downgrade. |
How it's sold: Sold by metric ton in coils; specify substrate coating (g/m²), top/back paint thickness (microns), paint type, and RAL color.
What drives the price
- Substrate coating weight (as GI)
- Paint type (PVDF >> polyester) and film thickness
- Top + back coat microns
- Color and gloss matching
Lock these into the contract before you pay
Substrate coating g/m²
PPGI hides a galvanized layer that can be under-coated just like bare GI.
Paint type and micron thickness
Thin polyester sold as thick PVDF is the classic PPGI downgrade.
RAL color and gloss
Color mismatch across coils ruins a finished roof.
Scams most common to ppgi
Coating-Weight & Galvanizing Fraud
Both the zinc substrate and the paint film can be thinned below spec while invoiced full.
Bait-and-Switch Quality
PVDF sample, polyester production; premium color sample, off-shade production.
Forged Mill Test Certificates (MTC / EN 10204 3.1)
Paint and substrate figures on paper the coil does not meet.
Red flags in a quote or sample
- PVDF price that matches polyester (too good to be PVDF)
- No micron figure for paint film
- Substrate coating weight omitted
Already paid and something's wrong?
If you received off-spec ppgi, a certificate that doesn't match, or your supplier has gone quiet after a deposit, move quickly. Recovery odds drop with every day that passes on a wire transfer.
Buying ppgi from China: FAQ
What grades of ppgi can I buy from China?
The most commonly ordered grades are PPGI (zinc substrate), PPGL (Al-Zn substrate), Paint: RMP / PVDF. Always pair the grade with its standard on the purchase order so the mill test certificate can be matched to what you actually receive.
What is the most common scam when buying ppgi from China?
Coating-Weight & Galvanizing Fraud. For this product specifically: Both the zinc substrate and the paint film can be thinned below spec while invoiced full. The defense is to specify the exact grade and standard, require a verifiable mill test certificate, and commission independent pre-shipment inspection.
What should I check before paying for ppgi?
Lock down substrate coating g/m², paint type and micron thickness, ral color and gloss in the contract, verify the supplier is a real manufacturer, and never release the balance until an independent inspection confirms the goods.
I already paid a Chinese supplier for ppgi — what now?
Act fast: contact your bank about a recall on the wire, gather all contracts and communications, report the pattern so others are warned, and review the documented cases to understand your options. The sooner you act on a redirected or disappeared payment, the better the odds.