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Thread: silicone grease and gelcoat

  1. #1

    silicone grease and gelcoat

    I was using silicone liquid grease, it's used for lubricating cables in pipes etc, and after using it the rag I used to wipe off the excess I unthinkingly left on top of the boat while I accepted a parcel and some remained on the gelcoat. Now I wiped off the silicone and interestingly the gloss and colour came up better than ever. Now somewhere in my dim memory banks I recall that silicone was bad news for gel coat, anyone any experience or knowledge about this.

  2. #2

    Re: silicone grease and gelcoat

    Hi Dignity, when manufacturing fibreglass products you cant use silicone based wax on moulds as the gelcoat wont sit on it. You will create fish eyes. Is this what you were thinking about?
    Tug Tellum
    Not all tools are usefull.
    Nappies and politicians should be changed regularly for the same reason..

  3. #3

    Re: silicone grease and gelcoat

    Tug,it's quite possible what remains in the vestiges of my memory. There seems to be a lot on the net about removing silicone sealers from gelcoat, from what I understand the silicone gets right into the gelcoat and you virtually have to grind it back. I've tried cleaning the silicone off where the rag sat but the area is still deeper in colour and remains relatively glossy. Its also confusing when you read labels of certain polishes and waxes that state either they contain silicon (and PTFE) or they are silicone free. I just don't know what effect direct sunlight will have on it.

  4. #4

    Re: silicone grease and gelcoat

    If you look at gelcoat under a microscope You will see the porosity (some times you can see it with out a microscope or magnifying glass if its really bad) These porosity holes will hold silicone or wax or anything that you spill on the gelcoat. As you say most of what you read on the net is about removing silicone that was used to seal something like windows/fittings etc. Grinding will get rid of most of it but probably not all. I dont know of what effect sunlight/uv has on the silicone that you used. I would imagine that the silicone would break down eventually,hopefully before you need to do a gelcoat repair.The waxes we use in manufacturing are Carnuba based waxes and these dont contain silicone. We also use a sealer resealer glaze on moulds to try to fill porosity in tooling gelcoat prior to application of coats of wax.. This material also has a light cutting compound
    Hope this helps. I dont profess to know it all .
    tug tellum
    Not all tools are usefull.
    Nappies and politicians should be changed regularly for the same reason..

  5. #5

    Re: silicone grease and gelcoat

    Don't know about gelcoat but I do know that panelbeaters love touching up cars that are silicone wax polished............not. I think there is a paint additive that will allow it to stick but without it I think it just runs.

  6. #6

    Re: silicone grease and gelcoat

    Thanks Scott, I suspect it's as tug-tellum says the gelcoat is porous, I guess I'll just have to polish and wax the rest to match, just hoping it sits there inert and does nothing.

  7. #7

    Re: silicone grease and gelcoat

    Quote Originally Posted by tug_tellum View Post
    If you look at gelcoat under a microscope You will see the porosity (some times you can see it with out a microscope or magnifying glass if its really bad) These porosity holes will hold silicone or wax or anything that you spill on the gelcoat. As you say most of what you read on the net is about removing silicone that was used to seal something like windows/fittings etc. Grinding will get rid of most of it but probably not all. I dont know of what effect sunlight/uv has on the silicone that you used. I would imagine that the silicone would break down eventually,hopefully before you need to do a gelcoat repair.The waxes we use in manufacturing are Carnuba based waxes and these dont contain silicone. We also use a sealer resealer glaze on moulds to try to fill porosity in tooling gelcoat prior to application of coats of wax.. This material also has a light cutting compound
    Hope this helps. I dont profess to know it all .
    tug tellum
    Do you use a particular brand of carnauba wax, I've been trying to get hold of some Collinite as it was quite good when I had some once before but a bit hard to get locally.

  8. #8
    Ausfish Platinum Member
    Join Date
    Mar 2015
    Location
    Kalbarri, WA

    Re: silicone grease and gelcoat

    When I asked for a recommendation for a polish to seal my brand new fibreglass boat, the shipwright told me to look for a high silicone polish. Make of that what you will.

  9. #9

    Re: silicone grease and gelcoat

    Quote Originally Posted by ranmar850 View Post
    When I asked for a recommendation for a polish to seal my brand new fibreglass boat, the shipwright told me to look for a high silicone polish. Make of that what you will.
    Ranmar I would have thought you only need a good wax not polish for a new boat. Surprisingly Mason Marine Trimming in WA sell Collinite at quite a reasonable price, if I can't get some here I'll be getting some sent from there in O'Conner.

  10. #10

    Re: silicone grease and gelcoat

    The Starbrite premium polish and cleaner wax from Whitworths contain PTEF. They are also petroleum based vs water based such as Dulon

    Ive also used the Starbrite polish on my black car. Shine is amazing and water beads beautifully. Although I have my boat professionally polished with the Dulon component system.

  11. #11

    Re: silicone grease and gelcoat

    I wonder if acetone will clean it off?

  12. #12

    Re: silicone grease and gelcoat

    Quote Originally Posted by Noelm View Post
    I wonder if acetone will clean it off?
    i think it will but i would try putting some silicon grease on some timber first to try. I certainly wouldnt leave it on more than what t takes to get the grease off. On the other hand, if it leaves a nice shine, maybe cover the whole boat with it, lol.

  13. #13

    Re: silicone grease and gelcoat

    Try sending the manufacturers an email outlining your concerns. They may have the answer as I would think they may have come across this in research and development.

    Can’t hurt


    Sent from my iPhone using Ausfish forums

  14. #14

    Re: silicone grease and gelcoat

    Both turps and acetone cleans if off the surface but the problem is a slightly porous surface. I'll go over it with some wax once I've rubbed enough to try and remote it.
    I've put it on a number of surfaces to see if I can get it out as per Andy56 suggestion and found one interesting item, I have some old coaming rubber which I've kept (I know a hoarder but it's in a pile of stuff ready to go) and I was surprised to find that if I rubbed it in it gave the rubber a new shiny look which is interesting as I've tried many different ways to restore it in the past. On application it felt like it was cutting through the previous crap, it only takes very little silicone and does leave a slightly almost sticky touch but I might try the power buff it to see how it goes. Maybe it needs another compound to finish it off. I did recently see a 500ml jar of something similar for sale at $82 but don't recall where.

  15. #15
    Ausfish Platinum Member Funchy's Avatar
    Join Date
    Jun 2011
    Location
    Caloundra
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    Re: silicone grease and gelcoat

    You haven't ruined my boat have you Sam?

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