Short answer. Repainting profiled sheeting all over is not worth it: the factory coating is applied to the coil in a heated line, and a spray can does not reproduce it. But touch-up does make sense — on scratches down to bare steel, on damaged screw heads and on some cut edges. It is cosmetics and a barrier, not a restored coating, and the difference matters.
What the factory protection is made of
Two different mechanisms, and paint replaces only one of them.
| Layer | How much in our steel | How it protects |
|---|---|---|
| Zinc | 100-275 g/m² — that is 7-19 µm per side | sacrificially: it dissolves instead of the steel and shields even an exposed cut edge next to it |
| Polymer | 22-32 µm from our main suppliers, up to 50 µm on SSAB Pro BT | as a barrier: it keeps water off the metal |
| Together | 29-69 µm per side |
Spray paint works as a barrier only and contains no zinc. So it closes the damage against water, but it gives none of the electrochemical backup that steel is galvanised for in the first place.
When touch-up is justified
| Situation | What to do | Why |
|---|---|---|
| Scratch to bare metal from installation | degrease, zinc-rich primer, then enamel to match | the primer puts zinc back into the damaged spot |
| Screw head with damaged coating | enamel, spot only | small area, minimal water load |
| A visible cut edge that nothing can cover | primer + enamel | better than bare metal, worse than a flashing |
| Cut edge under a flashing | do nothing | the flashing covers it better than any paint |
| Rust across the face of the sheet | painting is pointless | the coating is already gone, paint over rust flakes off |
The main rule: covering a cut edge with a flashing beats painting it. A flashing from the same coil gives you the colour, the geometry, and it does not age separately from the sheet. There is a separate article about that.
Why repainting a whole sheet is a bad deal
The factory polymer goes onto an unwound coil in a continuous line: the steel is degreased, primed, coated and baked. Reproducing that on an installed roof is impossible in principle — there is no heat, no evenness and no thickness control.
The practical consequence: a painted sheet looks refreshed for a season or two, then the paint starts peeling exactly where the metal works — on the bends of the rib and around the fasteners. After that the surface has to be stripped, and the condition is worse than before painting.
If the coating is gone over a large area, it is more honest to price a replacement sheet. Steel for a fence or a shed costs less than paint materials and labour spent twice.
What we do not do
We do not sell paint or repair enamels, and we do not paint or repaint sheets. Colour is set by the coating on the coil at the steel mill — that is a metallurgical operation, not ours.
How to order
Step 1. Work out what is actually damaged
Isolated scratches — touch-up. Rust across the face — replacement. A visible cut edge — a flashing.
Step 2. Count what you need
For flashings — the running length of the section. For a sheet — the dimensions of the plane.
Step 3. Order from the same coil
Call (067) 077-56-77, Mon-Fri 08:00-17:00. Production 1-2 days, delivery another 1-5 days.
FAQ
Do you have repair enamel to match your sheet? We do not sell it. That is a question for paint suppliers — ask for enamel in the RAL code you need.
Can galvanised steel without polymer be painted? Yes, but it needs a primer made for zinc: ordinary paint adheres badly to bare zinc.
Does painting void the warranty? The warranty covers the factory coating. Installation damage and painting done yourself are not covered by it.
How long does a touched-up scratch last? It depends on the location: longer on a vertical wall, less on a horizontal slope under running water. It is a delay, not a replaced coating.
What about a cut edge with no flashing available? Zinc-dust primer and enamel to match. And keep in mind that this is a temporary fix.