Mould on sealant | MotorhomeFun | The Motorhome Support and Social Network

Mould on sealant

Jun 28, 2019
114
51
Pembrokeshire
Funster No
61,987
MH
Dethleffs T6501B
Exp
New at this
2011 Dethleffs coach-built... the white sealant used to seal the join between the cab to the habitation, is 'mouldy', as in it has lots of black/grey staining. Is there a way to freshen this up without damaging the bodywork or the sealant? Also, l'm guessing this sealant eventually loses its flexibility. Is it common practice to strip it out and reseal?
 

Robert Clark

LIFE MEMBER
Jul 12, 2014
10,927
60,344
East Sussex
Funster No
32,375
MH
N&B Arto 78F
Exp
Since June 2014 - learning something new all the time
I use traffic film remover in a spray bottle

Power Maxed Tfr5000 Concentrate Traffic Film Remover, 5 Liters Amazon product

Spray it on
Then agitate with a stiff brush
Rinse completely

Been using it for a couple of years now
It’s the only thing I’ve found that really cleans dirty silicone
 
Mar 15, 2019
333
377
Funster No
59,148
MH
AutoCruise Stardream
Exp
Newbie April 2019
Got the same problem on a 2007 Autocruise, tried various things.

So far I've tried Autoglym MH cleaner, cillit bang mould remover, t-cut, toothbrush, brake cleaner. Toothbrush with cillit worked best but still left some stains. Reckon I'll ultimately end up replacing it on ours
 
OP
Oldgustaf
Jun 28, 2019
114
51
Pembrokeshire
Funster No
61,987
MH
Dethleffs T6501B
Exp
New at this
Lots of 'solutions' (ha, ha) here. Thanks very much. Just worried that something like Cillit would damage the cab paintwork. There's a Dettol mould spray too but that also could damage the paintwork maybe???
 
Nov 11, 2013
1,847
5,236
Tewkesbury
Funster No
28,984
MH
Hymer T-SL 668
Exp
March 2014
Hagesan do a mould remover that works incredibly well on bathroom sealant but I’ve never tried it on a vehicle. I tried everything a while back to clean deep black mould from around a bath but this stuff was genius and left the sealant looking like new again.

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M-J

Jan 15, 2019
985
1,130
Funster No
58,012
MH
Bessacarr E562
Exp
1 year
It will be road/traffic dirt rather than mould. As Robert Clark said above TFR should shift it.
 

Silver-Fox

LIFE MEMBER
Sep 5, 2014
5,844
9,533
Cheltenham Spa
Funster No
33,201
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Rapido
Exp
im a not so newbie
If you use TFR be careful how you use it and mind your eyes and skin.

It is super acidic and designed to clean curtain side trailers 😳
 
OP
Oldgustaf
Jun 28, 2019
114
51
Pembrokeshire
Funster No
61,987
MH
Dethleffs T6501B
Exp
New at this
TFR won't strip off the cab paint?

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Aug 29, 2010
608
474
Nuneaton. Only when I have to.
Funster No
13,456
MH
Hymer Exsis t564
Exp
Since Sept 2010
Aldi black streak cleaner and a toothbrush work for me. Spray some on to run down, leave it a few minutes, then reapply and brush quite hard with a wet toothbrush. Do it quite often to stop difficult ingraining. It's about the only cleaning I do when on the road, apart from the windscreen. Saves major grief later! 😁
 

Silver-Fox

LIFE MEMBER
Sep 5, 2014
5,844
9,533
Cheltenham Spa
Funster No
33,201
MH
Rapido
Exp
im a not so newbie
Aldi black streak cleaner and a toothbrush work for me. Spray some on to run down, leave it a few minutes, then reapply and brush quite hard with a wet toothbrush. Do it quite often to stop difficult ingraining. It's about the only cleaning I do when on the road, apart from the windscreen. Saves major grief later! 😁
Is this stuff acidic as well.
I was told about some stuff from Lidl or Aldi that removed black streaks.

Had a look on the bottle then decided not to but it 😊

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Aug 29, 2010
608
474
Nuneaton. Only when I have to.
Funster No
13,456
MH
Hymer Exsis t564
Exp
Since Sept 2010
Is this stuff acidic as well.
I was told about some stuff from Lidl or Aldi that removed black streaks.

Had a look on the bottle then decided not to but it 😊
Not as far as I am aware. Just seems to be a strong detergent. Probably the same basic stuff as their caravan cleaner in a stronger dilution. Seems to have the same basic ingredients as all detergents. Washing up liquid, shampoo, handwash etc. I have used the caravan cleaner on occasion for this job but had to scrub harder/longer. Also, I have tried applying Autoglym super resin polish once the sealant is clean and dry in the hope it would provide a barrier layer but only moderately effective.
 
Last edited:
OP
Oldgustaf
Jun 28, 2019
114
51
Pembrokeshire
Funster No
61,987
MH
Dethleffs T6501B
Exp
New at this
That's exactly the kind of problem I have. Citrus Blitz looks great - and probably smells nice too :). Thanks!
 
OP
Oldgustaf
Jun 28, 2019
114
51
Pembrokeshire
Funster No
61,987
MH
Dethleffs T6501B
Exp
New at this
I think there is mould. I also don't like the way the sealant appears to have dried out. We've only had the van a month. Doesn't look like the sealant has ever been cleaned.

IMG_5415.jpegIMG_5415.jpeg

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Aug 29, 2010
608
474
Nuneaton. Only when I have to.
Funster No
13,456
MH
Hymer Exsis t564
Exp
Since Sept 2010
Have just seen the posts from Two on Tour and Oldgustaf and have to say that does look like mould. More like you might find round a shower. The cleaning I spoke about earlier was really only roadgrot. Brake dust, diesel exhaust etc, especially lower down in line with the front wheels.
 

M-J

Jan 15, 2019
985
1,130
Funster No
58,012
MH
Bessacarr E562
Exp
1 year
Seems odd to have mould, maybe parked in a shaded spot for long periods.

A mould and mildew spray would do it but you would need to wipe it off the paint as you apply to the seal. Play it safe and apply with a small paint brush for more control.

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Mar 15, 2019
333
377
Funster No
59,148
MH
AutoCruise Stardream
Exp
Newbie April 2019
I was planning to use sikaflex 512 when I get round to ours. But be interesting to see if there is anything better
 
Feb 2, 2015
1,279
2,305
Staffordshire
Funster No
34,975
MH
A class Adria Sonic
Exp
we are still learning
I was planning to use sikaflex 512 when I get round to ours. But be interesting to see if there is anything better
Sikaflex 512 is great stuff for sticking things down . It does though ...go yellowish after a while!
Soudal RV 61 is now being used in most caravan and motorhome repair shops. It does not fade or yellow

Kev

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Feb 25, 2018
1,183
1,214
Essex
Funster No
52,564
MH
Bailey 754 Autograph
Exp
Very Little
If one decides to replace mouldy sealant what is the "best stuff" to use?
i would be wary about removing any sealant around exterior joints/bodywork. if its not leaking or damaging the sealant, then your problem really is just aesthetics, perhaps someone will know whether its safe just to apply a new silicon bead over the top of the old, if it will adhere?
 
May 27, 2015
2,100
5,402
Bedford
Funster No
36,573
MH
A Class
Exp
Long time
Personally if it was mine I would want it stripped out and new sealant, sooner or later it’s going to allow damp in!
 
Jan 9, 2014
18
4
Scotland
Funster No
29,628
MH
C Class
Exp
Since 2006
Anyone know what effect (if any) that the products mentioned above might have on the skin of fibreglass or GRP wall panels?

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Jul 24, 2014
425
379
North cotswolds
Funster No
32,530
MH
Peugeot Boxer Symbol Auto
Exp
since 2010
A spray all over with 'wet n forget' will keep it away for quite a long time. I used this on my old MH worked a treat.
 

TheBig1

LIFE MEMBER
Nov 27, 2011
12,510
18,039
Dorset
Funster No
19,048
MH
A class
Exp
many many years! since I was a kid
NEVER use silicone sealant on a motorhome, only urethane sealants
 
Sep 23, 2014
4,848
12,052
Ayrshire Scotland
Funster No
33,478
MH
Swift Kon-Tiki 640
Exp
Since 1964 Gosh that makes me feel old.
I've used TFR rather brutally in the past, bear with me, I use it neat from a spray bottle but only doing a tiny bit at a time then rinsing with copious amounts of water.
The TFR needs to be the caustic type, not the feeble ordinary stuff the snowflakes want us to use.
Gloves are required & the whole vehicle will need a polish or wax treatment as the TFR strips it back very quickly.
The good news is that it only takes 30 seconds per area, leave it on for about 15 seconds then rinse & it only needs doing once every couple of years.

I have an aversion to yellowing sealant or external plastic work on caravans or motorhomes & bought a Bessacarr caravan a number of years ago which was in a shocking state & had it looking like new in no time. Sadly I do not have before & after photo's but I'm sure you'll agree that it works.
I've been doing this for many years but, you must remember to rinse thoroughly.

I know this post will boggle the minds of the purists on here but, if you don't want to try it that is of course your decision.
1AAAA Bessacarr.JPG
Oh I meant to say, that I bought this caravan really cheaply due to the state of it, I had it for two years, never had to retreat it & sold it on for a £3k profit.

When using this stuff it can be alarming as the yellowing runs off in a one go & you can actually see it running down the van.
Its also brilliant at cleaning plastic garden chairs, or white plastic drain pipes on your house, brings them up like new.

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Last edited:
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