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Green growth on car roof rails

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Clive Hartland06/02/2022 15:09:42
2838 forum posts
40 photos

My car a VW lives outdoors. We live in a wooded semi rural area.

The car roof rails have a green growth along the crevices.

Also on the trim under the doors.

The felt liners that the windows have as a seal also get this green growth.

Any suggestions of how to prevent, remove, fix.

David George 106/02/2022 15:16:35
1873 forum posts
505 photos

Try burning coal near to the vehicle as the soot and fall out prevents the growth of moss and lichens. We never used to get such growths til the clean air act.


Martin King 206/02/2022 15:19:30
1018 forum posts
461 photos

Hi All,

the best case of this green stuff used to be in the sliding window channels of early Mini’s, you could grow potatoes in a good example!

Cheers, Martin

blowlamp06/02/2022 15:21:20
1655 forum posts
106 photos

Use a pressure washer?


Clive Hartland06/02/2022 15:23:23
2838 forum posts
40 photos

David, I have'nt got a chimney, the whole area is surrounded by woodland. I am going to try a mild vinegar solution to see if it helps. The houses around here are all less than 20 years old, so are built to the clean air act.

It is an estate car and now I have found it under the edge of the rear door where it festers unseen!

Clive Hartland06/02/2022 15:29:18
2838 forum posts
40 photos

I have a pressure washer so that is one answer, thanks blowlamp.

pgk pgk06/02/2022 15:31:23
2605 forum posts
293 photos

It happens here for the same reasons. OH doesn't wash her car and the previous one had moss growing even on the main panels - took me a goodly while to clean it before trade-in after being unwashed for 7 years.
Apparently a copper wire on roof ridge can stop moss growing on tiles so perhaps a few bits wedged into panel gaps might work as a preventative?


Spurry06/02/2022 15:31:46
221 forum posts
72 photos

A pressure washer will definitely get rid of it, on a temporary basis, but be very careful near the rubber seals as they can be damaged with just a little too much pressure. (Experience teaches!)

peak406/02/2022 15:33:07
1786 forum posts
193 photos

I wish I knew the answer, as we have the same problem at our house in Buxton.
There is something odd about the microclimate, just around our property, as first algae, and then moss grows rapidly.
It's not just the crevices like roof rails and around lights, but even over the vehicle paintwork after a month or two.
It even grows on the windscreen wipers

The tarmac and concrete paths and drives get covered in no time at all.
On these, I've used sodium percarbonate crystals, often known as oxygen bleach, to quite good effect as a moss killer. I can't use anything toxic, as our groundwater drains into next door's pond.

I'm reluctant to try it on metalwork though, as Landrovers corrode fast enough as it is.

Do we have any chemists amongst us?


Speedy Builder506/02/2022 15:37:26
2653 forum posts
219 photos

Clive, try planting it. You never know, you may get a younger model !

I get the same on my front gates. Pressure washing does get it off, but it is difficult to get it out of the crevices of the scroll work and it comes back every couple of years. I did wonder about bleach which is what they use (in some form) on roof tiles to remove moss. I made a wooden garage out of Douglas fir and treated it with this product Treatment . 3 years down the line and not a spot of "green stuff" and the garage is overshadowed by an ash tree on one corner and a plum tree on another, but no idea as to what it would do on rubber/metal etc. This product is available in the UK UK supplier and for those building wooden sheds etc, I can heartily recommend it.


Martin Kyte06/02/2022 16:16:14
2794 forum posts
53 photos

If it's green then it will be photo synthesising so reducing the light may slow things down a little. Try painting it with a solvent like IPA or maybe try one of the mould killers sold for bathrooms.

regards Martin

Edited By Martin Kyte on 06/02/2022 16:17:06

Robert Atkinson 206/02/2022 16:21:47
1246 forum posts
20 photos

Best treatment for this is benzalkonium chloride. A detergent and biocide. Available in several forms including patio cleaner. I use Dettol's washing machine cleaner as a source. Dilute 50:50 or 30:70 with water and spray or brush on the green stuff Leave for a few hours and wash off. Helps prevent re-growth.

Robert G8RPI.

Tim Stevens06/02/2022 16:26:36
1622 forum posts

Just remember the rules about using herbicides etc - use them for what they are for, and not otherwise. Something to do with not destroying the planet.

I have seen shed roofs crossed by old wireless aerials - plain uninsulated copper. The line where the drips from the aerial fell had no moss and no lichen. Just a thought.


RMA06/02/2022 16:45:58
324 forum posts
4 photos

I use sulphate of iron to kill moss on lawns and paths. My car suffers to some extent on one side. That's the side that is mainly hidden from the sun. I turn it round when I think of it and it goes. Be careful with pressure washers, they can reach parts you didn't know existed and they'll strip graphics in no time

Speedy Builder506/02/2022 16:47:25
2653 forum posts
219 photos

Tim, zinc does the same. No moss below the zinc flashings.

HOWARDT06/02/2022 16:57:38
932 forum posts
39 photos

I think it is more a case of cleaning the vehicle more often. A car I saw the other day was more living green than dead paint. It never seemed to be a problem, perhaps modern water based paints are more prone than older cellulose based ones,

Emgee06/02/2022 17:01:19
2445 forum posts
291 photos

I have found pressure washing is liable to lift paintwork if there are any chipped areas so now use it with care but a stiff hand brush soon cleans the growth from widow seals. If still available diluted JEYES fluid disinfectant clears and helps reduce further growth.


Nicholas Farr06/02/2022 17:13:12
3421 forum posts
1592 photos

Hi, I get the same problem on my car, I scrape it off with a small plastic scraper when it gets too bad to look at it.

Regards Nick.

Robert Atkinson 206/02/2022 17:29:21
1246 forum posts
20 photos

I suggested benzalkonium chloride because:

A. It is safe and non-persistent. Other uses include throat lozenges and preservative in eye drops. LD50 for Rats is 2 g/kg (table salt is 2 g/kg). Just keep it out of the fish pond.
B. It isintended for use as an algicide. The Dettol product is a different application but is sold in a more useful 250 ml rather than 2.5 l for patio cleaner.
C. it does not damage paintwork or rubber seals e.g. around windows.
D. It's non staining

Robert G8RPI.

Clive Hartland06/02/2022 22:05:45
2838 forum posts
40 photos

All good info, I will report back soon. Clive

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