Cleaning dirty silicone/mastic seals?

Discussion in 'Motorhome Chat' started by Baker69, Aug 12, 2009.

  1. Baker69

    Baker69 Read Only Funster

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    What does everyone recommend for cleaning the dirty mastic/silicone seals around such things as the door, external toilet housing, fridge vents etc?

    Or is it simply better to remove it and apply new mastic?
     
  2. Douglas

    Douglas Read Only Funster

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    If it is 100% silicone it will just peel off but I think that what you have is a compound of different polymers.

    You will find it all most impossible to remove the "bonding" with chemicals and you will have to use a mechanical method to remove it.

    One of my favorite ways is to use an angle grinder with a "cup wire brush", but take care the wire brush will go through plastic very easy, also for gods sake use goggles, the bits of wire that the brush will shed could cost you an eye!!

    The second method, but a little slower is to use a "stanley" knife, the kind that has a long blade that can, with care, be bent to go flat against the parent material.

    If the mastic is fresh you can reuse it but it does tend to dry out and lose its addision



    Doug...
     
  3. Highwayman999

    Highwayman999 Read Only Funster

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    I use autoglym polish on the corner of an old cotton t shirt...Bit time consuming but does the trick for me. :Smile:
     
  4. GJH

    GJH Funster Life Member

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    I've had some success with those sponge erasers. JML sell one, as do Aldi. Also sold under Duzzit brand and, no doubt, others.

    They also work for getting rid of dead flies on the Luton.

    Jill reckons she's seen stories of damage to paintwork. I haven't experienced that with our van but if in doubt try on a hidden area.

    Graham
     
  5. spindrifter

    spindrifter Read Only Funster

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    In some instances WD40 can work well - it has for me. Try a small bit first.

    Cheers

    David ..... (Spindrifter)
     
  6. sinbad1

    sinbad1 Deleted User

    Removing old silicone sealant can be tricky depending on the surface. One method is to use the blade of a craft knife

    Slide the knife blade behind and under the silicone with the blade against the surface. Take care not to scratch the surfaces.

    After slicing the sealant at both surfaces, use the blade to cut the silicone into sections. Place the blade back under the sealant and then lift it away from the surface

    Grab the loose end of the sealant and pull it gently, you should be able to lift the section of sealant away fairly easily.

    You can remove any remaining remnants of silicone by gently scraping it off with the knife blade. Try using the whole length of the blade and sliding it along the surface scraping the sealant as you go.

    regards
     
  7. scotjimland

    scotjimland Funster Life Member

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    If it's Silicone sealer, then as previously suggested , however if it is a non setting Mastic such as IDL .. the excess can easily be scrapped away using an old credit card then clean up using some white spirit .. no need to re apply mastic, what you are cleaning off is excess that has oozed out..

    White spirit will also clean up Silicone sealer.

    jim
     
  8. stagman

    stagman Deleted User

    Scrubs Wipes:thumb:
     
  9. alf

    alf Read Only Funster

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    If I read the OP correct it is to clean the mastic seal not remove any excess,
    it is most likely non setting sealant try a bit of WD40 on a cloth ( thinks !! old shirt tail will do ) on the sealant under the toilet door try not to get WD 40 on the bodywork it most likely wont' harm but will leave a smear to polish off.

    I would not try to remove if you have no leaks as this may start them off to reseal wll mean removing fittings etc as surface sealant on joints does not do much good.



    Alf
     
  10. pappajohn

    pappajohn Funster Life Member

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    hard work but try a toothbrush and toothpaste....it'll get into the tiny holes/imperfections in the mastic/silicone surface:thumb:
     
  11. Johns_Cross_Motorhomes

    Johns_Cross_Motorhomes Trader - Motorhome & Accessory Sales

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    Jims got it in one:thumb:

    Peter
     
  12. sinbad1

    sinbad1 Deleted User

    Well if its old and dirty I doubt you will recover it by just cleaning it, and chances are that the adhesion may not be as good as originally applied, in fact the action of cleaning often in the case of old silicon will tend to come away complete from the surface like a thick elastic strip.

    The choice is yours ;but personally i would remove and replace (depends how bad it is, if it can be lifted in places then there is no other option) and do the job right .

    regards
     
  13. wolfy62

    wolfy62 Deleted User

    I know B&Q sell a mastic sealant remover,it should be on the same shelf as the mastic sealant,im near sure Homebase sell it also.
    Garry
     
  14. Baker69

    Baker69 Read Only Funster

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    A lot of the problem is on dirty excessive mastic that has squeezed out. I'd like to cut this off but would probably leave it exposed to possible water ingress. This is a non-setting type of mastic and is the main problem and which is very dirty in colour. Could I cut all the exposed mastic off to save cleaning it and then do a small silicone seal around the item?

    Also the previous owner seems like he got a mastic gun for Xmas and sealed absolutely every conceivable external bodywork joint. The vast majority of it I would say was totally un-warranted and I have already removed some of his handy work. This is silicone mastic which is a bit easier to clean anyway.
     
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