Mar 21, 2026 · 3 min read

PPGI vs GI Coil: Coatings, Uses and Buying Guide

GI is galvanized steel with a zinc coating. PPGI adds a factory-applied organic paint system to galvanized steel. Choose between them according to the finish, fabrication process and exposure your product requires.

See our PPGI coil specifications and paint options or GI coil specifications for product ranges and order enquiries.

PPGI vs GI: What Changes?

Feature	GI coil	PPGI coil
Surface system	Metallic zinc coating; surface treatment as specified	Zinc coating plus pretreatment, primer and finish coats
Appearance	Galvanized surface, with spangle and finish specified in the order	Factory-applied colour, gloss and texture as specified
Purchasing focus	Grade, dimensions, zinc coating, surface treatment and forming requirements	All substrate requirements plus paint system, film thicknesses and colour approval
Fabrication	Check forming and any later painting requirements	Check forming compatibility and protection of the painted finish
Cost comparison	Include any downstream finishing and handling costs	Include the supplied finish, protective film and processing requirements

When to Specify GI

Consider GI when the galvanized finish meets the application requirements or when you plan a separate finishing process. If you intend to paint the material later, specify a surface treatment compatible with your preparation and paint process. Not every galvanized surface treatment is suitable for every paint system.

When to Specify PPGI

Consider PPGI when you need a coloured, factory-coated surface for roofing, cladding, panel facings or fabricated components. Agree the paint system and forming requirements before ordering. Factory painting does not remove the need for suitable handling, edge treatment and installation practices.

Compare the Full Specification

Grade and thickness: use the same grade requirements and distinguish base-metal thickness from total coated thickness.
Zinc coating: confirm designation, coating mass and inspection basis.
Surface or paint: for GI, specify treatment and appearance; for PPGI, specify primer, top and back coat, gloss and colour.
Fabrication: define the profile or bend, equipment limits, sample evaluation and protective film.
Delivery: align quantity, coil weight, packing, inspection and Incoterm when comparing costs.

There is no fixed price premium or service-life multiplier that applies to every PPGI and GI order. Coating, processing, environment and maintenance change the result. Obtain a dated quotation and evaluate the complete cost of the finished component.

ChinaCNU Supply and Verification

ChinaCNU is the export brand of Shandong Ruitong New Materials Co., Ltd., with a factory in Boxing County, Binzhou, and an export office in Qingdao. The overall PPGI thickness range is 0.12–1.50 mm; the overall GI range is 0.12–3.00 mm. Grade-specific combinations and tolerances are confirmed in the quotation.

MOQ starts from 25 metric tonnes. Typical production is 15–20 days after deposit and specification approval, including colour approval for painted material. Ocean transit is additional. Review certificate records and their current status, factory photographs and the product reference sheets.

Frequently Asked Questions

Does PPGI have a galvanized layer underneath the paint?

Yes. PPGI uses a galvanized steel substrate with an organic paint system. Prepainted aluminium-zinc coated steel is generally called PPGL and should be specified separately.

Can GI be painted after fabrication?

It can be, using a compatible surface preparation and coating process. Confirm the galvanized surface treatment and the requirements of the selected paint system with the coating supplier.

Does PPGI always last longer than GI?

A suitable paint system can add protection, but actual performance depends on the complete specification, exposure, forming, cut edges and maintenance. Avoid comparing service life without matching those conditions.