In short
Prepainted steel sheet is a coloured steel plate obtained by baking galvanized coil with primer and topcoat in a coating line and then cutting it to the required size in the cut-to-length line. Ipek Metal supplies PPGI sheet in thicknesses of 0.30–1.20 mm, with Z100–Z275 substrate and in RAL colours.
Prepainted steel sheet is a coloured steel plate obtained by baking galvanized coil with primer and topcoat in a continuous coating line and then straightening and cutting it to the required size in the cut-to-length line. Because the paint is applied not after the sheet has been cut into pieces but already at the coil stage and at a controlled oven temperature, the coating thickness remains uniform across the surface. Ipek Metal supplies prepainted galvanized coil and sheet (PPGI) to TS EN 10169 for coating and TS EN 10346 for substrate; in thicknesses of 0.30–1.20 mm, widths of 1000 and 1250 mm, and RAL chart colours, and produces sheet to the requested size with its coil cut-to-length service.
Prepainted steel sheet is not a single layer: layer sequence and function
When prepainted steel is mentioned, colour is the first thing that comes to mind; however, the product is a structure made up of layers that complement one another. Each of these layers performs a different function, and the sheet's performance in outdoor conditions depends on the entire sequence:
- Steel base: this is the load-bearing layer. In the prepainted products supplied by Ipek Metal, the substrate is galvanized DX51D+Z steel sheet.
- Zinc coating: this is the layer that protects the steel against corrosion; one of the classes between Z100 and Z275 is selected.
- Passivation: this is the surface treatment that ensures compatibility between the zinc surface and the paint.
- Primer: this is the intermediate layer that increases the adhesion of the topcoat to the surface.
- Topcoat: this is the final layer that provides the colour, gloss and outdoor durability.
In this sequence, the factor that determines the sheet's service life is not the colour on top but the zinc class beneath it. The paint protects the zinc from sunlight and mechanical wear; the zinc protects the steel from corrosion. Therefore, when comparing two quotations, the question to ask should not be "which colour" but "which zinc class and total coating thickness".
Dimensions and technical ranges of prepainted steel sheet
The technical framework of the prepainted galvanized coil and sheet supplied by Ipek Metal is summarised in the table below:
| Property | Range / Option |
|---|---|
| Substrate | Galvanized DX51D+Z (TS EN 10346) |
| Zinc coating | Z100 – Z275 |
| Thickness | 0.30 – 1.20 mm |
| Width | 1000 / 1250 mm |
| Paint system | Polyester (PE), SMP, PVDF |
| Paint thickness | Front side 20–25 µm, back side 5–12 µm |
| Colour | RAL chart (e.g. 9002, 3009, 5010, 6005, 7016) |
| Standard | TS EN 10169 (coating), TS EN 10346 (substrate) |
In prepainted products, the thickness range is narrower than for bare galvanized coil. Although the most commonly encountered range in the field is 0.40–0.70 mm, Ipek Metal supplies prepainted steel from 0.30 mm to 1.20 mm. In terms of width, 1000 and 1250 mm are standard; sheet length is determined according to request by cut-to-length processing from coil.
Prepainted steel sheet or prepainted coil?
Prepainted steel is basically sold in three forms: coil, cut-to-length flat sheet and formed product (trapezoidal or corrugated panel). The difference between these products, which are made from the same kilogram of material, comes not from the material but from the processing. Which form to choose depends on your production flow:
- Coil: suitable for manufacturers that have their own cut-to-length or forming line. The storage space requirement is lower; because it is the leanest form in the chain, the unit cost is also lowest at this stage.
- Cut-to-length sheet: practical for workshops that will use it directly in installation or in cutting and bending operations. It is prepared as straightened plates with clean edges in standard sizes or at the requested length.
- Formed product: used as profiled panel in roofing and façade works. When comparing cost per square metre, the profile's development factor must also be taken into account.
Ipek Metal offers prepainted galvanized coil and sheet both as coil and as cut-to-length plate. For the entire product family, you can visit the prepainted steel (PPGI) product page, and for the plate production process, the cut-to-length service page.
Three values to check when requesting a quotation
1. Zinc class (Z100–Z275)
The amount of zinc coating is the main variable that determines how well the steel will resist corrosion. While lower classes may be sufficient for indoor applications or work with a short service-life expectation, higher classes are preferred for exterior façades and projects with long service-life expectations. We covered in detail what the classes mean in the galvanized coating classes article.
2. Total paint thickness (µm)
In the prepainted products supplied by Ipek Metal, the front-side paint thickness is 20–25 µm and the back side is 5–12 µm. Paint thickness is given in microns; vague expressions such as "thick paint" are not sufficient for comparison. When requesting a quote, ask for the front and back side values separately.
3. Paint system: PE, SMP or PVDF
Polyester (PE) is the standard option for general use. SMP and PVDF are preferred for applications where UV resistance and outdoor performance stand out. We compared the advantages of the paint systems relative to one another in the PE, SMP and PVDF paint systems article.
Where is prepainted steel sheet used?
Prepainted galvanized sheet finds a place wherever a visible surface requires colour and aesthetics. Roof and façade claddings are at the top of the list. Prepainted steel in coil or sheet form is processed into trapezoidal, corrugated and similar profiled products to become the final cladding element. In addition, it is also preferred in different forms in sectors such as furniture and construction.
Colour is not merely an aesthetic choice. The standard colours in the RAL chart (for example 9002, 3009, 5010, 6005, 7016) meet the architectural expectations of different projects and make it easier to achieve the same shade when reordering if necessary.
Delivery and logistics
Prepainted steel sheet does not behave differently from bare steel during delivery either: Ipek Metal makes planned, documented and safe deliveries from its facility in Adana to Çukurova and across Turkey. Clarifying whether you want coil or cut-to-length plate as part of the order ensures that the shipping plan and packaging method are set up correctly from the outset.
Frequently asked questions
What is the difference between prepainted steel sheet and galvanized flat sheet?
The substrate of both is galvanized steel. In galvanized flat sheet, the surface is bare zinc; in prepainted steel, passivation, primer and topcoat are applied over this zinc surface. In other words, prepainted steel is the painted version of galvanized steel; corrosion protection still comes from the zinc beneath, while the colour and surface appearance come from the paint layer.
In what thicknesses and dimensions is prepainted steel sheet supplied?
At Ipek Metal, prepainted galvanized coil and sheet are supplied in thicknesses of 0.30–1.20 mm and widths of 1000 and 1250 mm. Paint thickness is 20–25 µm on the front side and 5–12 µm on the back side. Sheet length is determined not from a standard list but according to request by cut-to-length processing from coil.
What determines the service life of prepainted steel sheet?
Two values stand out as determining the sheet's outdoor performance: the zinc class in the substrate (Z100–Z275) and the total paint thickness. The paint protects the zinc from sunlight and mechanical wear, while the zinc protects the steel from corrosion. A comparison based only on the colour code overlooks these two decisive values.
Should I buy coil or cut-to-length sheet?
If you have your own cutting or forming line, coil is more suitable. If you will use the sheet directly in installation or on a cutting and bending bench, straightened plate cut to the requested length reduces both waste and labour load.
Get a quote for prepainted steel sheet for your project
Share the thickness, width, zinc class and RAL colour you need for roofing, façade or formed product manufacturing; the Ipek Metal team will plan the right solution for prepainted steel sheet and coil supply and cut-to-length service. Simply send your dimensions and colour information via the Request a quote page.
This article was prepared by the İpek Metal technical team. Contact us for values specific to your project.