Short answer
PPGI is prepainted steel on a galvanized (GI) metallic substrate. PPGL is prepainted steel on a galvalume (GL / AZ) metallic substrate. Outdoor durability depends on both the metallic coating and the paint system (PE, HDP, SMP, PVDF, film build, reverse side).
If a quote only says “color coil RAL 5012,” the buyer has not yet specified a product.
Substrate difference that matters
| Item | PPGI | PPGL |
|---|---|---|
| Metallic base | Zinc-coated (GI) | Al-Zn coated (GL) |
| Typical discussion | Z coating mass under paint | AZ coating mass under paint |
| Common use framing | Building panels, general color cladding | Roofing and outdoor panels where AZ substrate is preferred |
| RFQ must include | GI coating designation under the paint | AZ coating designation under the paint |
Related bare-metal comparison: GI vs Galvalume buyer guide. Related paint-vs-bare guide: PPGI vs galvanized coil.
Paint system and durability (buyer view)
Organic coating choice is not cosmetic only:
- PE (polyester): common for indoor or mild outdoor; confirm film thickness and warranty expectations with the mill.
- HDP / SMP: often selected when outdoor chalking and fade resistance need to improve versus standard PE.
- PVDF: typically discussed for higher-end architectural outdoor color stability; cost and formability trade-offs apply.
Also specify:
- Topcoat / primer structure and approximate µm when critical.
- Reverse-side coating.
- Gloss, texture (including wrinkle/matte if required).
- Protective film for roll forming and export handling.
Color and RAL
Use a RAL code or signed sample, not a verbal color name alone. Start with common export codes on the RAL colors tool, then lock:
- RAL / sample ID
- Gloss and texture
- Metamerism / multi-batch approval rule if panels ship in phases
RFQ checklist for PPGI / PPGL
- Substrate: GI or GL + coating mass.
- Paint system and intended outdoor class.
- Color reference (RAL / sample).
- Thickness × width; coil ID and weight limits.
- Forming route (roll form, bend radius, panel type).
- Inspection: adhesion, color ΔE if required, film continuity.
- Packing: film, corner protection, moisture control.
- Documents: MTC linkage, coating certificates as agreed.
Family product hub: PPGI / PPGL Color-Coated Steel Coil. If the coil becomes roofing sheet, add profile fields from the roofing profiles tool.
Key takeaway
PPGI vs PPGL is first a substrate decision, then a paint system and color control decision. Write both layers into the RFQ so price comparisons stay honest.
