Quick answer
Light surface scratches on a composite door usually polish out with a fine cutting compound and a soft cloth. Deeper scratches that catch a fingernail need a colour-matched filler and touch-up, and any scratch reaching the timber core underneath needs a professional repair rather than a DIY fix.
Overview
The GRP skin is tough but scratches happen - key marks, buggy wheels, pets. Light surface scratches polish out with a mild abrasive; deeper cuts need filler and colour match.
Symptoms
- Visible scratches on the door face.
Common causes
- Impact, keys, tools, animals.
What actually causes scratches on a GRP door skin
The gel-coat skin on a composite door is tough compared with uPVC, but it isn't scratch-proof. In Cornwall the most common culprits we see are pushchairs and buggies clipping the lower panel, key rings swinging against the lock face, dog claws near the letterbox, and bramble or climbing plant growth scraping the surface in a breeze.
Sandy grit tracked in on shoes and dragged across a threshold-height panel is another coastal-specific cause that doesn't come up as much inland. It's fine, but abrasive, and repeated contact over a season can leave a network of fine hairline marks rather than one obvious scratch.
Working out how deep a scratch actually is
Run a fingernail gently across the mark. If it glides over without catching, it's a surface scratch in the gel-coat only and is a good candidate for polishing out. If your nail catches or you can see a colour change at the base of the scratch, the damage has gone through the pigmented layer.
A scratch that shows a different colour, often a pale or brownish tone, at its base has usually reached the timber or composite core beneath the GRP skin. That's a different repair altogether and not one to tackle with a polish or a pen.
- Doesn't catch a fingernail: surface only, polish candidate.
- Catches slightly, same colour throughout: shallow, filler pen candidate.
- Different colour visible at the base: reaches the core, needs a professional look.
Polishing out light surface scratches
For genuinely superficial marks, start with the mildest option: a warm soapy wash first, because plenty of what looks like a scratch is actually a scuff mark sitting on top of the finish rather than cut into it. If it's still visible once dry, a fine automotive cutting polish applied with a soft microfibre cloth in small circular motions will often work it out.
Work a small section at a time, check progress regularly rather than going hard in one pass, and finish with a wipe of clean water to remove any polish residue. Don't use anything labelled as a heavy cutting compound or rubbing compound for bodywork, as these are more aggressive than a gel-coat needs and can dull the surrounding satin or gloss finish.
Colour-matched touch-up for deeper scratches
For scratches that catch a nail but haven't reached the core, a colour-matched touch-up pen or filler stick is the standard approach. Most composite door manufacturers offer these matched to their specific colour ranges, and it's worth ordering one at the time you buy a new door so you already have the exact match on hand for the years ahead.
Clean and dry the area thoroughly first, apply thinly, and build up in light layers rather than one thick pass, which tends to look obviously patched. Leave it to cure fully before touching or wiping the repaired area.
When a scratch needs a professional repair
Once a scratch has broken through to the timber core, a colour pen won't hold up long term because moisture can track in around the exposed core if it isn't properly sealed first. That's a job for a trade repair rather than a DIY fix, since it involves proper sealing and colour-matching to blend invisibly.
We assess these on site and give an honest view of whether a professional repair will look acceptable given the door's age and colour, or whether the mark is in a position, like eye level on the main face, where you'd notice any blending line and might prefer to think about replacement instead.
Preventing repeat scratches in a coastal garden setting
Since brambles, climbing roses and coastal shrubs grow fast in Cornwall's mild, damp climate, a door that was clear of vegetation in spring can be getting scraped by autumn. A quick trim-back of anything within arm's reach of the door twice a year avoids most plant-related scratching.
For buggy and bike traffic through a porch, a simple kick plate or even just training the household to lift rather than wheel items through the doorway saves the lower panel from the repetitive scuffing we see most often on family homes.
- Trim back climbing plants and shrubs within reach of the door twice yearly.
- Lift, don't wheel, buggies and bikes through a narrow porch.
- Keep key rings on a short fob rather than a long chain that swings against the door.
Scratches on holiday let doors between guest changeovers
Rental properties see more scratch-causing traffic than an owner-occupied home simply through volume of different guests, luggage and pets over a season. A quick visual check of the door face at each changeover catches small marks while they're still in the easy-polish category, rather than letting several seasons of scuffs accumulate into something more visible.
Keeping a colour-matched touch-up pen in the property's maintenance kit means small marks can be dealt with immediately rather than waiting for a scheduled maintenance visit, which matters more for kerb appeal on a let than on a private home.
What the guarantee does and does not cover on scratched doors
Manufacturer guarantees on composite doors are built around material and colour performance, not accidental damage, so a scratch from a buggy, dog claw or dropped tool is not something any guarantee is designed to cover, whoever supplied the door. What the guarantee does still protect is the colour match of any professional repair carried out using the correct manufacturer touch-up system for your specific door.
If a scratch is unusually deep and appears on a door that is otherwise well within its guarantee period, it is still worth mentioning at any routine visit, because it occasionally points to a hardware fitting sitting slightly proud and catching against something repeatedly, which is a separate adjustment issue worth sorting at the same time.
A seasonal pattern to scratch damage in Cornwall
Scratches tend to cluster around specific times of year rather than appearing evenly. Spring and summer bring more scratching from garden tools, bikes and buggies being moved through porches, plus fast-growing brambles and climbing plants that were dormant over winter suddenly reaching the door face.
Autumn brings a different pattern, with sandy grit tracked in from beach walks and dropped leaves scuffed underfoot near the threshold. Winter tends to be quieter for new scratches but is when existing ones show up most, since low winter sun at a shallow angle throws even shallow surface marks into sharp relief.
A quick trim of nearby plants each spring and a threshold mat that catches grit before it reaches the door face are the two habits that head off the bulk of seasonal scratching before it starts.
North- and south-facing doors show scratches differently
A south-facing door in strong, low-angle light, particularly in winter afternoons, shows up fine scratches far more readily than the same mark would on a shaded north-facing door, simply because of how light rakes across the surface. Homeowners with south-facing doors sometimes report scratches that were actually there for months but only became visible once the sun angle changed.
North-facing doors hide light scratching better but are more likely to develop a damp, slightly tacky surface film from reduced drying time, which grit can then embed into more easily during cleaning if you are not careful with your cloth technique.
When a scratch is beyond cosmetic recovery
A scratch is beyond a straightforward cosmetic repair once it has gone through the pigmented GRP skin and exposed the timber or composite core beneath, especially if that exposure has been there for some time and has taken on moisture, which shows as a darker, slightly swollen area around the scratch itself. At that point, a colour-matched filler on its own is not enough because the core needs proper sealing first.
It is also worth being realistic about scratches on the main face at eye level, where even a well-executed professional touch-up will show a faint blending line under close inspection or particular lighting. In that specific position, some homeowners prefer to live with a very minor, honestly-assessed mark rather than risk a repair that draws more attention than the original scratch.
How we assess scratch damage during a site visit
On site we run the same fingernail test we would talk you through over the phone, but we also check the scratch under raking light from a torch held at a low angle, which reveals depth far more accurately than daylight alone. That tells us immediately whether we are dealing with a polish job, a filler-pen repair, or a core-sealing job.
We also look at the wider door for related causes, such as a handle backplate sitting slightly loose and swinging with a key ring, or vegetation close enough to keep causing the same damage. Fixing the underlying cause is as much a part of the visit as repairing the mark itself.
Typical repair costs in Cornwall
| Work | Typical price | Notes |
|---|---|---|
| DIY polish kit | £10-£20 | For light surface scratches, self-applied |
| Colour-matched touch-up pen | £12-£25 | Per colour, worth keeping in stock |
| Professional scratch repair | £60-£120 | For scratches reaching the core |
Guide prices only — we confirm the cost after seeing the door.
When to call a professional
- Deep scratches through to the timber core.
Prevention
- Trim brambles and climbing plants near the door.
