# What causes the black streaks?



## 107088 (Sep 18, 2007)

I read with interest the questions about cleaning off the black streaks from vehicles, and wondered where the heck they come from....do manufacturers put a secret " blck streak dispenser" onto the motorhomes and caravans they sell, and if so how does it replenish itself?

I cant recall seeing the black streak issue on vans, cars, bikes, boats, or, come to think of it, on emergency service vehicles either.

So....rather than trying to find stuff thats best to cleans them with, I thought I'd ask what they are, and where they come from. Thats because if its a mastic type problem, then surely change the mastic, if its another build thing..build them differently.




P.S. If I suddenly start to distribute a genius Black Streak remover...ignore above.


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## Spacerunner (Mar 18, 2006)

Just my personal theory.

The roof will collect much more dust and debris than any other part of the motorhome simply because its a large flat horizontal surface.

This layer of dirt is then washed off by rain and runs down the sides of the 'van.

When it reaches obstructions such as a window frame the 'run-off' is diverted horizontally. In doing so, it concentrates an extra amount of dirt until it reaches the end of the obstruction and continues on its downward journey.

The extra dirt that it collected then drops out of the run-off and is deposited on the walls under the ends of the window frame creating the dreaded black streak. This then dries and if sunny gets baked onto the surface.

Further dust collection and rainfall just helps to build up the effect.

So, in theory, if you want to avoid black streaks, then keep your roof clean.


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## greenasthegrass (Oct 27, 2007)

I agree its the surface area. My mum has a white car and that gets black streaks as well keep telling her to wash it more!

Makes me laff though when after a good washing down Drew gets disgruntled when birds have been eating elderberries and then he covers up his baby and they do it on the cover as well - if only he'd wash my kitchen floor as often! :roll: 

Greenie


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## danielf (May 11, 2005)

*Black Streaks....*

I never had black streaks on my Rambler as I was able to keep the roof clean and polished much easier.... I did fine that keeping van with a good layer of polish on it stopped them from forming on the van sides, if they did they just wipped off....

Now I have a coachbuilt, and I haven't touched the roof yet, and it is filthy dirty I'm getting black streaks. Van was very dirty when bought, sides and cab now all polished up..... just need to do the top now.... and a new rear bumper... and some deadlocks... and some...........

Daniel.


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## mangothemadmonk (Aug 6, 2006)

I was always told it was from rubber seals and mastic joints.

Johnny F


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## Spacerunner (Mar 18, 2006)

mangothemadmonk said:


> I was always told it was from rubber seals and mastic joints.
> 
> Johnny F


If that is the reason, then why do you get black streaks at roof level where there is no rubber seal and any mastic is white?


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## mangothemadmonk (Aug 6, 2006)

I never get black streaks on the roof so can't help you there. 

I would suggest you washed your roof more if that's where you think it's coming from.

Johnny F


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## Spacerunner (Mar 18, 2006)

mangothemadmonk said:


> I never get black streaks on the roof so can't help you there.
> 
> I would suggest you washed your roof more if that's where you think it's coming from.
> 
> Johnny F


See previuos post at 09:51.....


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## mangothemadmonk (Aug 6, 2006)

Spacerunner said:


> See previuos post at 09:51.....


There isn't one.

Have you got your site clock set right as the first post was 10:51 

Johnny F


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## Spacerunner (Mar 18, 2006)

mangothemadmonk said:


> Spacerunner said:
> 
> 
> > See previuos post at 09:51.....
> ...


Nah! clock always wrong...in a world of me own... :lol: :lol: :lol: :lol:


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## mangothemadmonk (Aug 6, 2006)

:wink: :wink:


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## Velvettones (Jul 31, 2007)

asked this at swift rally and was told it was deposits in the rainwater - nothing to do with building materials used, obviously road dust etc wont help either though


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## some-where-in-oxford (Apr 18, 2006)

Where does all the fine grains of tyre rubber go as your tyres wear?

Pixies collect it at night, and hide it on motorhome roofs.


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## mangothemadmonk (Aug 6, 2006)

Holds hand up :-# :-# 

Johnny F


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## carprus (Jun 22, 2008)

Spacerunner said:


> Just my personal theory.
> 
> The roof will collect much more dust and debris than any other part of the motorhome simply because its a large flat horizontal surface.
> 
> ...


Without doubt the most logical reason . :wink:


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## fencer (Feb 21, 2008)

Black streaks are caused by metal objects (aluminium etc) fitted to the coachwork. Its a type of rust (oxidation) acidic rain promotes this oxidation and leaves black streaks. Best to use a quality polish to help stave-off the oxidation of the metallic parts fitted to the coachwork. Or you could simply apply polish along the areas where the streaks occur.


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## 107088 (Sep 18, 2007)

some-where-in-oxford said:


> Where does all the fine grains of tyre rubber go as your tyres wear?
> 
> Pixies collect it at night, and hide it on motorhome roofs.


Thanks for all the replies guys, and depite your best effort at reaonable or scientific answers, this is clearly correct one.......  :roll:


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## teemyob (Nov 22, 2005)

*Aluminium*



fencer said:


> Black streaks are caused by metal objects (aluminium etc) fitted to the coachwork. Its a type of rust (oxidation) acidic rain promotes this oxidation and leaves black streaks. Best to use a quality polish to help stave-off the oxidation of the metallic parts fitted to the coachwork. Or you could simply apply polish along the areas where the streaks occur.


Yes, mainly caused by Aluminium and black sealants

Trev.


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## 113016 (Jun 5, 2008)

*Funny*

The funny thing is, that before I recently polished my van with a top quality polish, I had very few black marks  
But now since polishing, I am plagued with them :evil: :evil:


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## Spacerunner (Mar 18, 2006)

_Yes, mainly caused by Aluminium and black sealants _

Don't have aluminium or black sealant.

OMG! What can it be?.. 8O


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## Rapide561 (Oct 1, 2005)

*Black streaks*

Hello - the other option is to try to disguise the black streaks - a black motorhome maybe.

Russell


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## Spacerunner (Mar 18, 2006)

*Re: Black streaks*



Rapide561 said:


> Hello - the other option is to try to disguise the black streaks - a black motorhome maybe.
> 
> Russell


Then we'd get white streaks!!

How about Zebra stripes?


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## howardirene (Mar 26, 2006)

its carbon deposits so i'm told, I've found that MER, german polish which is good for motorhomes/caravans is the only cure, tried it and i had no streaks for months, downside its so expensive but so good try it


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## jiffyman (May 11, 2005)

howardirene said:


> its carbon deposits so i'm told, I've found that MER, german polish which is good for motorhomes/caravans is the only cure, tried it and i had no streaks for months, downside its so expensive but so good try it


I havent used MER for years!!

Did try Meguiars, that seemed ok, but think I do have a bottle of MER in the garage somewhere, so might give it a go.....


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## sylke (Sep 10, 2007)

*BLACK MARKS*

EVERYONE HAS WD40 IN THE GARAGE, IT DOES THE JOB EASY AND IT'S CHEAP :lol:


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## jhelm (Feb 9, 2008)

*Re: BLACK MARKS*



sylke said:


> EVERYONE HAS WD40 IN THE GARAGE, IT DOES THE JOB EASY AND IT'S CHEAP :lol:


How do you use it, spray on the aluminium or on the streaks. Does it prevent them or clean them?

I found a tough stain/bug remover bought at the local harware store works pretty well for removing them.


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## asprn (Feb 10, 2006)

*Re: BLACK MARKS*

Try searching for:-

Mcklords
Muc-off

Doesn't answer Bandy's question, but does answer some others. 

WD40 contains OIL, which I would not put remotely near the surface of my van.

Dougie.


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## chrisgreen (Jan 13, 2008)

*Re: BLACK MARKS*



asprn said:


> Try searching for:-
> 
> Mcklords
> Muc-off
> ...


as dougie says wd40 will damage the surface of your van,it will penetrate behind the paint and lift it.
i also drive a white lwb pug boxer van for my work,and suffer with streaking where the water runs of the roof at the back,i think its carbon as in the winter when all the coal fires around here spark up,the black streaking is horrendous.


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## some-where-in-oxford (Apr 18, 2006)

howardirene said:


> its carbon deposits so i'm told, I've found that MER, german polish which is good for motorhomes/caravans is the only cure, tried it and i had no streaks for months, downside its so expensive but so good try it


Is this the polish that is demonstated at the shows?

The guy polishes a mini bonnet, then sets it alight with lighter fuel!

When the flames go out the polish is still intact!


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## mangothemadmonk (Aug 6, 2006)

some-where-in-oxford said:


> When the flames go out the polish is still intact!


But this inteior is burnt out 8) 8) 8)

Johnny F


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## DTPCHEMICALS (Jul 24, 2006)

Black streaks appear on grp panel on my mh and is higher than window rubbers.
It is simply atmospheric dust washe down with rain.
All hardsurface cleaners should, at the correct dilution eradicate them.
In 25 years of caravaning and mh ing i have used all kinds of cleaners and polishes.
There is no magic cure.
TFR Flash liquid my Casclean will clean it off.


dave P


Please do not all order at once.


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## waddy (Apr 21, 2006)

*black streaks*

A correction to an assumption yes WD 40 does contain oil But it is fish oil and will in no way harm paint work or metal surfaces in fact it is widely used by signwritters to to clean all manner of surfaces and it also leaves a protective surface. as for the cause of black streaks my guess would be 50% atmospheric pollution and 50% material degredation ( ie rubber trims round windows sealants and metal verdigris) only one fault with this theory i frequently go aloft to clean the roof of my motorhome the highest point of the various attachments on this is the dimpled plastic cover of the air con unit which is a cream/ offwhite colour this is always the filthiest part to clean even when the van has been static for a long period so perhaps atmospheric pollution plays an even bigger part in black streaks. perhaps the only solution to the problem is from Star Wars a cloaking device or better still get rid of all the gas guzzling 4 wheel drive tuggers that bung up the campsites these days sans life !


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## mangothemadmonk (Aug 6, 2006)

*Re: black streaks*



waddy said:


> But it is fish oil


That must be why it is sometimes advertised as an additive when fishing for pike with a dead bait. So if it's safe for fish......

Johnny F


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## Kelcat (Apr 20, 2008)

Having spent Sunday afternoon on the roof of my 'new to me' 06 plate MH I have to say I'm appalled at the cr*ppy quality of the sealants used (I work in the glazing industry & we wouldn't use this stuff). Most of it has degraded & it's all full of mould - I'm pretty positive that it's the source of the black streaks on my van. I suppose that a thin film of the sealant might also attract additional atmospheric pollution, I'm going to speak to the dealer about warranty issues but I think I'll be replacing with a higher grade.


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## waddy (Apr 21, 2006)

*Pike Baits/WD 40*

You are correct mango it is also used by sea anglers sprayed onto their bait 
I personally only fish for Carp and as yet have yet to try spraying it on my boillies ! .


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