Factory Prepainted Steel – Metallic-coated steel with pretreatment, primer and finish paint layers.
PPGI & PPGL Options – Galvanized and aluminum-zinc coated substrates available.
Custom Metallic Coating – Z30–Z275 and project-specific coating requirements can be discussed.
PE SMP HDP PVDF – Multiple paint systems, RAL colors, gloss and surface finishes available.
Complete Export Documents – MTC, COO and complete commercial and shipping documentation available.
Prepainted Steel Coil is steel that receives its protective and decorative organic coating before it is formed into the final product. Rather than painting roofing sheets, panels or fabricated components after production, the steel is coated continuously while still in coil form.
This process allows the substrate, metallic coating, primer, finish paint, color and coating thickness to be controlled under factory conditions. The finished coil can then be processed directly through roll-forming, slitting, cutting and panel-making equipment.
Henan GDD supplies prepainted steel to roofing manufacturers, sandwich-panel factories, roll-forming companies, steel distributors and industrial fabricators. Specifications can be developed around the customer's production equipment and final service environment rather than simply matching a color.
For customers changing suppliers, an existing MTC, coil label or purchase specification is particularly useful. Two coils with the same nominal thickness and RAL color can still differ significantly in metallic coating, paint chemistry, coating thickness and mechanical properties.
| Item | Specification |
|---|---|
| Product Name | Prepainted Steel Coil / Prepainted Coated Steel Coil |
| Product Types | PPGI / PPGL / Customized Prepainted Steel |
| Substrate | Hot-Dip Galvanized Steel / Aluminum-Zinc Coated Steel |
| Common Grades | DX51D, DX52D, DX53D, S250GD, S280GD, S320GD, S350GD, SGCC, SGCH or Equivalent |
| Common Standards | EN 10169, EN 10346, ASTM A755/A755M, JIS G3312 or Customer Specification |
| Thickness | Approximately 0.12 – 1.20 mm or Customized According to Grade and Production Capability |
| Width | Approximately 600 – 1250 mm or Customized |
| GI Zinc Coating | Commercially Approximately Z30 – Z275 g/m² Total Both Sides or Customized According to Applicable Specification |
| Common Zinc References | Z30, Z40, Z60, Z80, Z100, Z120, Z140, Z180, Z200, Z225, Z275 or Agreed Coating Mass |
| PPGL Metallic Coating | Al-Zn Coating Such as AZ50 – AZ180 or Customized According to Applicable Specification |
| Metallic Coating Structure | Normally Double-sided; Differential or Special Single-side Requirements Subject to Mill Capability |
| Paint System | PE, SMP, HDP, PVDF or Customized Organic Coating |
| Top Coating Thickness | Typically 10 – 35 μm or Customized According to Paint System and Application |
| Back Coating Thickness | Typically 5 – 25 μm or Customized |
| Color | RAL Colors / Customer Color Sample / Customized Color Matching |
| Surface Finish | Glossy, Semi-gloss, Matte, Wrinkle, Textured, Wood Grain, Printed or Customized |
| Coil ID | 508 mm / 610 mm or Customized |
| Coil Weight | Typically 3 – 8 MT or Customized According to Customer Equipment |
| Processing | Slitting, Cut-to-length, Corrugating, Profiling and Customized Processing |
| Applications | Roofing, Wall Cladding, Sandwich Panels, Prefabricated Buildings, Ceilings, Doors, Appliances and Roll-formed Profiles |
| Inspection | Dimensions, Metallic Coating, Paint Thickness, Color, Gloss, Surface, Mechanical Properties and Third-party Inspection Where Required |
| Available Documents | MTC, Certificate of Origin, Export License Where Applicable, Commercial Invoice, Packing List, Bill of Lading and Customs Documents |
| Packing | Waterproof Wrapping, Protective Steel Sheet, Edge Protectors, Steel Straps and Seaworthy Export Packing |
| Trade Terms | EXW, FOB, CFR, CIF |
Metallic coating and paint specifications should always be stated separately. A specification such as “0.45 mm prepainted coil, RAL 9002” is incomplete unless the substrate, coating mass, paint system, film thickness and applicable tolerances are also confirmed.
Prepainted Steel Coil is metallic-coated steel that is painted before being converted into a finished component. The coating process is completed continuously on a coil-coating line rather than after roofing sheets, wall panels or other components have already been formed.
The word “prepainted” therefore describes when the coating is applied: before downstream forming.
This allows manufacturers to purchase ready-finished material with a controlled color, surface appearance and coating system and then process it directly into the required profile.
The visible paint is only the outer part of the finished material.
A typical PPGI structure contains a steel substrate, zinc coating, surface pretreatment, primer and finish coat on the exposed side. The reverse side normally contains steel, zinc, pretreatment and a back coating.
PPGL follows a similar organic coating process but uses an aluminum-zinc coated substrate beneath the paint.
Understanding the substrate is important because two coils can look nearly identical from the painted surface while having substantially different metallic coating systems underneath.
PPGI production normally begins with a galvanized steel coil that already meets the required mechanical, dimensional and zinc-coating specification.
Steel grade, thickness, width and zinc coating are selected according to the final application and forming requirement.
Oil, dust and processing residues are removed from the galvanized surface before coating.
The metallic surface receives a controlled pretreatment designed to improve coating adhesion and support corrosion performance.
Primer is applied between the metallic substrate and finish coat. It helps create a stable coating system and improves adhesion.
The exposed surface receives the required PE, SMP, HDP, PVDF or other organic finish in the selected color and surface appearance.
The reverse side receives a back coating selected according to the intended use. It does not necessarily use the same paint thickness as the exposed surface.
The coated strip passes through curing ovens where the paint system develops the required film properties and adhesion.
Paint thickness, color, gloss and visible surface quality are checked according to the agreed specification.
The finished strip is recoiled and prepared for roll forming, slitting, cutting or international shipment.
Ordinary galvanized steel and prepainted galvanized steel share a zinc-coated base, but their finished surfaces are different.
GI Steel Coil normally retains its metallic zinc surface. It is widely used for HVAC ducts, structural profiles, fabrication and applications where a factory-applied decorative color is unnecessary.
Prepainted galvanized steel adds pretreatment, primer and organic finish coatings over the GI substrate. The coating provides color and adds another barrier between the zinc layer and the environment.
For roofing and wall panels, this allows the manufacturer to profile a finished colored product without operating a separate painting line.
Paint does not make the zinc coating unnecessary.
The organic coating is primarily a protective barrier and decorative surface, while zinc provides metallic corrosion protection to the underlying steel.
Zinc becomes particularly relevant around cut edges, local scratches and areas where the organic coating may be damaged during forming or installation.
This is why two prepainted coils with the same RAL color and paint thickness should not automatically be treated as equivalent when their zinc coating masses are different.
Standard hot-dip galvanized substrate for PPGI is normally zinc coated on both surfaces.
When a specification refers to a total zinc coating mass, the stated value generally represents the combined coating on the two surfaces under the applicable specification.
For example, a nominal total coating mass of 100 g/m² distributed approximately equally would mean roughly 50 g/m² on each surface.
This division is useful for understanding the coating structure, but actual side-to-side distribution remains subject to production control and applicable tolerances.
True single-sided galvanized steel is a special product rather than the normal substrate used for PPGI.
In a single-side specification, one surface receives zinc while the opposite surface remains uncoated or receives another specified treatment.
Buyers requiring this construction should clearly identify the required zinc mass on the coated side and the required condition of the opposite surface.
Availability depends on the production route and mill capability and must therefore be confirmed before quotation.
Differential galvanizing means both surfaces receive zinc, but the target coating mass is intentionally different between Side A and Side B.
It can be useful where the exposed surface requires greater metallic protection than the protected reverse surface.
Differential coating should not be confused with true single-sided galvanizing.
When unequal coating is required, the target coating on each surface should be stated separately because not every continuous galvanizing line supports the same differential configurations.
In many international commercial quotations, Z30 is used to describe approximately 30 g/m² total zinc coating when the buyer and supplier define the term that way.
If the coating is approximately equally distributed, that would correspond to about 15 g/m² on each side.
Z30 is a relatively light zinc coating and is generally considered for protected or cost-sensitive applications rather than demanding exterior exposure.
Because Z30 is not a formal coating class under every international standard, the actual coating mass in g/m² should be confirmed in the purchase specification.
Z40 is another commercial description frequently encountered in export markets and is often used to indicate approximately 40 g/m² total zinc coating when defined that way by buyer and supplier.
With approximately equal distribution, this would represent about 20 g/m² on each surface.
Like Z30, it should be considered a relatively light metallic coating and selected only where the application and customer specification allow it.
Under commonly used EN-style coating terminology, Z100 represents approximately 100 g/m² nominal total zinc coating across both surfaces.
An approximately equal-coated product would contain around 50 g/m² on each side.
Z100 is frequently requested for roofing, wall panels and general building products where buyers require more metallic protection than very light commercial coatings.
Z275 represents approximately 275 g/m² nominal total zinc coating under commonly used EN-style terminology.
It provides a substantially larger zinc reserve than light commercial coatings such as Z30 or Z40.
However, final product life cannot be predicted from zinc coating alone. Paint chemistry, film thickness, local climate, cut-edge exposure, installation and maintenance also affect service performance.
Buyers should be careful when comparing coating designations from different standards.
Commercial or EN-style Z terminology is generally discussed using grams per square metre, while ASTM metallic-coating designations such as G30, G60 and G90 use a different designation system.
A quotation stating Z40 should therefore not automatically be interpreted as ASTM G40 simply because the numerical value appears similar.
When changing between standards, compare the actual coating mass and test requirements rather than only the designation number.
PPGI uses hot-dip galvanized steel as the metallic-coated substrate.
It is widely used for corrugated roofing, wall panels, sandwich panels, ceilings, prefabricated buildings and general construction products.
The complete specification normally includes the substrate grade, zinc coating, paint system, top and back coating thickness, color and coil dimensions.
PPGL uses an aluminum-zinc coated substrate, often referred to commercially as Galvalume or Aluzinc, beneath the organic paint system.
It can be produced using similar colors and PE, SMP, HDP or PVDF finishes as PPGI.
Because the metallic substrate is different, PPGI and PPGL should not automatically be treated as technically interchangeable even when the visible color is identical.
The key difference lies below the paint.
PPGI uses zinc-coated galvanized steel, while PPGL uses an aluminum-zinc alloy coated substrate.
Both products can be made in the same RAL colors, gloss levels and organic coating types.
The correct substrate should be selected according to corrosion environment, forming requirement, cut-edge behavior and project specification.
Polyester, commonly abbreviated as PE, is one of the most widely used coating systems for standard building products.
It provides a practical balance between cost, formability, color selection and general-purpose performance.
PE is commonly used for standard roofing, wall panels, ceilings and general prefabricated-building products.
Silicone Modified Polyester uses modified polyester chemistry to provide different weathering and hardness characteristics from basic general-purpose PE.
SMP is commonly considered for exterior roofing and cladding applications where additional durability is required.
Actual performance depends on the coating formulation, so the abbreviation SMP should be supported by an agreed coating specification where project performance is critical.
High Durability Polyester is selected for projects requiring improved exterior durability compared with conventional polyester systems.
It is commonly considered for roofing and wall cladding where weather resistance and long-term appearance are important.
HDP can provide a practical solution where the project requires more than general PE but does not specifically require a PVDF system.
PVDF systems are often specified for architectural applications requiring strong weatherability and long-term color retention.
They are commonly considered for façade systems, premium cladding and selected roofing projects with demanding outdoor exposure.
Because PVDF usually carries a higher cost than general PE, coating selection should follow the project environment and expected performance rather than price category alone.
The paint system should be chosen according to service environment, expected appearance and required durability.
Standard general-purpose products frequently use PE. SMP or HDP may be considered where improved outdoor durability is required, while PVDF is commonly used for selected architectural applications with more demanding weathering requirements.
UV exposure, humidity, industrial pollution, coastal salt, expected service period and color-retention requirements should all be reviewed during specification.
The exposed and reverse surfaces of prepainted steel usually perform different functions.
The visible side typically receives primer plus the main decorative finish coat. The reverse side generally receives a back coat that may be thinner and formulated differently.
A commercial specification might use approximately 15–25 μm or another agreed film thickness on the exposed surface and a thinner coating on the reverse side.
For sandwich panels or roofing exposed to internal condensation, buyers should also pay attention to the back coating rather than specifying only the top surface.
RAL color references are widely used for international prepainted steel orders.
Surface options can include glossy, semi-gloss, matte, low-gloss, wrinkle, textured and decorative printed finishes.
The same nominal RAL color can appear slightly different when gloss, texture and coating chemistry change.
Projects requiring strict visual consistency should use an approved physical sample as the production reference.
Roofing manufacturers use prepainted master coils to produce corrugated, trapezoidal, tile-profile and other roofing panels.
The material needs sufficient formability to pass through roll-forming equipment without unacceptable coating cracking or delamination.
Key purchase specifications include steel grade, actual thickness, metallic coating, paint type, film thickness, width, RAL color and coil weight.
Wall cladding places considerable emphasis on appearance because a large coated area remains visible after installation.
Buyers should consider color consistency, gloss, coating system and project exposure in addition to steel thickness.
For large buildings where panels from different production batches may be installed next to each other, batch planning can help reduce visible color variation.
Sandwich panels use prepainted steel skins together with insulation cores such as EPS, PU, PIR or mineral wool.
Exterior and interior surfaces may require different thicknesses, colors and coating constructions.
Surface treatment and back coating should also be compatible with the panel-production and bonding process.
Prefabricated warehouses, workshops, cabins and modular structures commonly use prepainted steel for roofing and wall systems.
Factory-coated material provides a finished appearance without requiring the prefab manufacturer to paint every panel after profiling.
Roof panels, wall sheets and trims can be coordinated using compatible colors and coating systems for a consistent building appearance.
Prepainted steel is also used in cabinets, doors, equipment panels, ceiling systems and selected appliance components.
These applications can require tighter surface-quality control than standard roofing material because the coating is viewed at close range.
Formability, scratch resistance, gloss and color consistency should be matched with the finished manufacturing process.
A complete inquiry should contain more information than thickness and color.
Buyers should provide substrate type, steel grade, thickness, width, metallic coating, paint type, top and back coating thickness, RAL color, gloss or texture, coil ID, maximum coil weight and required quantity.
The final application should also be stated because roofing, sandwich panels, façades and appliance components have different coating priorities.
If an existing material already performs well, sending the current MTC or coil label helps establish a more reliable technical reference.
A lower PPGI quotation does not necessarily represent the same product at a lower price.
One supplier may quote Z30 with standard PE, while another quotes Z100 with a heavier top coat. Both may simply appear as “0.45 mm PPGI” in a short commercial offer.
Base steel grade, whether thickness is quoted before or after coating, metallic coating mass, paint chemistry, film thickness, coil weight and dimensional tolerance should all be compared before judging the price difference.
RAL color defines appearance, not the complete steel and coating specification.
Paint remains dependent on a suitable metallic-coated substrate underneath it.
A total Z100 coating does not normally mean 100 g/m² on each individual surface.
These terms are frequently used commercially but should be backed by a clearly stated g/m² requirement.
The reverse surface can still encounter moisture or condensation after installation.
Coil weight should remain within the customer's uncoiler, crane and warehouse handling capacity.
A roofing manufacturer may require DX51D-based PPGI in several standard colors for continuous corrugated-sheet production.
In addition to color and nominal thickness, the factory confirms zinc coating, PE paint thickness, coil width and maximum coil weight before purchase.
Maintaining similar mechanical properties between colors helps reduce roll-forming adjustments when production changes from one coil to another.
A sandwich-panel producer may use different prepainted specifications for exterior and interior skins.
The exterior surface can require greater weathering performance, while the interior material may prioritize clean appearance and cost efficiency.
Coil width, bonding compatibility and back-coat condition are reviewed together with color and thickness.
An exterior building project may specify HDP or PVDF rather than standard PE because long-term appearance and weather exposure are more important.
The project buyer can confirm metallic coating, finish paint, gloss and approved physical color sample before production.
A distributor replacing an existing source may send current coil labels, MTCs and color samples for comparison.
The replacement material is then reviewed by substrate, zinc or Al-Zn coating, paint system, dimensions and coil weight rather than matching only the commercial product name.
These examples describe typical procurement workflows. Customer names, confidential pricing and proprietary specifications are not published without authorization.
Once a coil specification has been successfully processed, repeat buyers normally pay close attention to consistency.
Common checks include actual thickness, width tolerance, metallic coating, color difference, gloss, paint thickness, forming behavior, surface condition, coil weight and packing quality.
For visible roofing and cladding projects, maintaining stable color between production batches can be particularly important.
Prepainted Steel Coil inspection can include dimensions, metallic coating information, paint-film thickness, color, gloss, surface condition and mechanical properties according to the order specification.
Surface inspection checks for scratches, dents, coating damage, contamination, edge defects and other visible issues.
Where required, coating adhesion, bending performance and other agreed tests can be reviewed according to the applicable standard or inspection plan.
Product photographs, coil-label photographs, packing photographs and loading photographs can be supplied according to customer requirements.
Material documentation helps connect the delivered coil with its agreed technical specification.
Depending on the mill and product, documentation can include steel grade, dimensions, metallic coating designation, mechanical properties, coil number and other relevant production information.
Coil labels support traceability during warehouse receiving and downstream processing.
Customers requiring particular certificate information should state these requirements before order confirmation.
Independent third-party inspection can be arranged according to the scope agreed in the purchase contract.
Inspection can cover dimensions, surface condition, color, coating information, markings, quantity, documentation, packing and loading.
Any additional laboratory tests should be confirmed before production so that testing methods, sampling and acceptance criteria are clear.
Henan GDD supports international Prepainted Steel Coil shipments with technical, commercial and customs documentation prepared according to contract and destination requirements.
Available documents can include MTC, Certificate of Origin, export license where applicable, commercial invoice, packing list, bill of lading and customs declaration documents.
Product photographs, coil-label photographs, inspection photographs, packing photographs and container-loading photographs can also be provided according to agreed requirements.
Destination-specific certification, legalization, chamber endorsement and other special import-document requirements should be confirmed before order placement.
Painted coil surfaces need protection from moisture, impact and abrasion during long-distance transportation.
Export packing can include waterproof wrapping, protective steel sheets, inner and outer edge protectors, reinforced steel straps and suitable supporting skids.
Coil labels can identify grade, dimensions, metallic coating, color, coil number, net weight, gross weight and customer shipping marks.
Loading arrangements should consider individual coil weight and suitable securing to reduce movement during shipment.
Henan GDD supplies Prepainted Steel Coil to roofing manufacturers, sandwich-panel factories, prefab-building producers, steel distributors and industrial fabricators.
We support PPGI and PPGL substrates together with customized metallic coatings, PE/SMP/HDP/PVDF paint systems, RAL colors and coil specifications.
For specifications using Z30, Z40, Z100 or Z275 terminology, we can review the actual coating requirement in g/m² to reduce misunderstandings during quotation.
Existing MTCs, coil labels, purchase specifications and physical color samples can be reviewed when customers need to replace an existing supplier.
Our related supply range includes GI Steel Coil, Galvalume Coil, PPGI, PPGL and Color Coated Steel Coil products, allowing buyers to consolidate related coated-steel sourcing where appropriate.
MTC, Certificate of Origin, export license where applicable and complete commercial and shipping documentation can be provided according to contract requirements.
Prepainted Steel Coil is metallic-coated steel that receives pretreatment, primer and factory-applied organic coatings before downstream forming.
PPGI is one type of Prepainted Steel Coil using a galvanized steel substrate. PPGL uses an aluminum-zinc coated substrate.
GI normally retains its metallic zinc surface. Prepainted GI adds pretreatment, primer and finish paint over the galvanized substrate to provide color and additional barrier protection.
Standard PPGI normally uses hot-dip galvanized steel with zinc coating on both surfaces. Single-side and differential coatings are special specifications.
They are commonly used commercially for approximately 30 g/m² and 40 g/m² total zinc coating when buyer and supplier define them that way. Because usage is not universal across every standard, the actual g/m² requirement should be confirmed.
Normally no. Under commonly used EN-style terminology, Z100 refers to approximately 100 g/m² nominal total zinc coating across both surfaces.
PE is widely used for general applications. SMP and HDP can be considered for improved outdoor durability, while PVDF is commonly selected for demanding architectural applications requiring stronger weathering and color-retention performance.
Yes. RAL references and customer-provided color samples can be used. A physical approved sample is recommended where strict color matching is required.
Yes. MTC, Certificate of Origin, export license where applicable, commercial invoice, packing list, bill of lading and other agreed export documents can be provided.
Please provide substrate type, steel grade, thickness, width, zinc or Al-Zn coating, paint system, top and back coating thickness, RAL color, gloss or texture, coil ID, coil weight, quantity, destination port and required documentation.
Looking for Prepainted Steel Coil for roofing, wall cladding, sandwich panels, prefabricated buildings or industrial production?
Send Henan GDD your substrate, steel grade, thickness, width, metallic coating, paint type, coating thickness, RAL color, surface finish, coil ID, coil weight, quantity, destination port and documentation requirements.
If your current specification only states something such as “0.45 mm PPGI, Z40, RAL 9002,” you can also send the existing MTC, coil label or supplier quotation. We can compare the complete substrate and coating construction before preparing a replacement offer.
