How to Remove Black Streaks from a Caravan or Motorhome
Black streaks are removed with a dedicated caravan shampoo, warm water and a soft brush — worked top to bottom in shade, then rinsed thoroughly. The streaks are airborne pollution and algae carried down the panels by rainwater running off the roof, seals and awning rail, so they return unless you clean the run-off points too.
What actually causes black streaks?
Rain washes over your caravan's roof collecting traffic film, diesel soot, algae and dirt trapped in seals, rails and around rooflights. As it runs down the sides in narrow channels, it deposits that grime in vertical streaks — which then bake onto the gelcoat or ACS panels in the sun. Under-roof fittings (awning rails, window top seals, aerials) are the usual culprits, which is why streaks appear in the same places every time.
Step-by-step removal
- Pick your moment. Clean in shade on a cool panel — shampoo dries too fast on hot surfaces and leaves smears.
- Rinse first. Get loose grit off with a hose so you're not dragging it around like sandpaper.
- Wash with a proper caravan shampoo. A concentrate like LeisureTime Concentrated Caravan Cleaner & Shampoo is formulated for gelcoat, ACS panels and decals — it lifts traffic film and streaking without stripping polish or damaging seals the way household detergents and washing-up liquid can (salt content in dish soap corrodes aluminium trim over time).
- Work top to bottom with a soft brush or wash mitt, panel by panel, keeping everything wet.
- Give streaks a second pass. Apply shampoo solution directly to stubborn streaks, leave 1–2 minutes, then agitate gently. Avoid abrasive pads — they scratch gelcoat and dull decals.
- Rinse thoroughly and dry with a microfibre drying towel to prevent water spots.
Stopping them coming back
Clean the sources: run the brush along the awning rail, window top seals and roof edges where grime collects. A twice-a-season roof wash makes the biggest difference — see our guide to the best way to clean a caravan. Finish with a polish or protective wax; a sealed surface gives streaks nothing to key onto, so next time they rinse off rather than needing a scrub.
What about black streak "miracle" removers?
Strong solvent-based streak removers work fast but can soften decals and strip wax, leaving panels less protected than before. For routine cleaning, a good shampoo used regularly beats an aggressive remover used desperately. Check your caravan handbook too — manufacturers like those represented by the National Caravan Council specify what's safe on bonded panels, and warranty small print can exclude damage from unsuitable cleaners.
The full kit list (and what each item costs you if you skip it)
You need less than you think: a concentrated caravan shampoo (one bottle lasts a season — LeisureTime's concentrate dilutes into many washes), a soft wash brush with a telescopic handle for roof edges, a wash mitt for panels, two buckets (one wash, one rinse — the two-bucket method stops you re-applying grit), a microfibre drying towel, and a step ladder rated for the job. Skip the telescopic brush and you'll never clean the run-off points that cause streaks; skip the second bucket and you'll slowly sandpaper your gelcoat with the dirt you just removed; skip the drying towel and hard-water spots will etch into panels the sun bakes at 60°C.
Motorhomes: two extra jobs
Motorhome owners get the same body streaking plus two extras. First, the cab: the transition from automotive paint to habitation panels means testing your cleaner on both — a proper caravan shampoo is safe for automotive paint, so wash the whole vehicle with one product rather than switching. Second, the overcab area and wind deflectors trap a ridge of grime that streaks the windscreen surround and cab doors; brush these every wash. A-class owners should also clear the windscreen gutter channels, which feed concentrated dirty water down the A-pillars — the most stubborn streaks on any A-class are almost always traceable to blocked gutters, and thirty seconds with the hose prevents them.
Frequently asked questions
What is the best thing to clean black streaks off a caravan?
A concentrated caravan shampoo, warm water and a soft brush, with a second targeted application on stubborn streaks. Avoid abrasives and household detergents.
Can I use washing-up liquid on my caravan?
It's not recommended — dish soaps contain salt and strip protective wax, dulling gelcoat and corroding trim over time. Caravan shampoo costs pennies per wash diluted.
Will a pressure washer remove black streaks?
It helps rinse, but pressure alone won't shift bonded streaks — and high pressure near seals and vents can force water in. Keep it on a wide fan, at distance, and let the shampoo do the work.
How often should I wash my caravan to prevent streaks?
A full wash every 4–6 weeks in the season, plus a roof and rail clean twice a year, keeps streaking to a quick-rinse problem.
Sources: National Caravan Council; Caravan and Motorhome Club.