Tony44935 Posted May 9, 2017 Share Posted May 9, 2017 Sikaflex 512, is it an acrylic ??? Thanks. Link to comment Share on other sites More sharing options...
andytw Posted May 10, 2017 Share Posted May 10, 2017 Polyurethane http://irl.sika.com/dms/getdocument.get/ed2853f3-8302-3581-b621-735f731906d4/pds_sikaflex-512caravan_uk_v01-07.pdf Link to comment Share on other sites More sharing options...
Tony44935 Posted May 11, 2017 Author Share Posted May 11, 2017 Thanks for that, looking at my question again , I've got it wrong, is it a silicone, and think I've found that answer but my next question, are all sealants used on Motorhome roofs silicone based ??? Also if not how would I find out which are not ??? Thinking of using eye ndfbond tape to back up the seals already done, but eternabond will not stick to silicone. Cheers. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted May 11, 2017 Share Posted May 11, 2017 As it says in the link andytw provided, Sikaflex-512 Caravan is a multi-purpose polyurethane-hybrid adhesive/sealant. It is not a ‘silicone’, though SIKA does market a range of silicone sealants (examples here) http://gbr.sika.com/en/solutions_products/sika-markets/joint-sealing/sanitary-sealants.html Polyurethane-hybrid products both bond and seal and have been commonly used for several years in motorhome construction as an alternative to traditional screw-it-all-together methods. As far as I’m aware it’s unlikely that a reputable motorhome manufacturer would use a silicone-based product on a motorhome roof. I don’t know what “eye ndfbond tape” is, but if your motorhome’s roof seals/rooflights have already been sealed http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Sealant-for-the-roof/46990/ presumably you’ll need to ask whoever did this what sealing-products they employed and then you should be able to check whether these were ‘silicone’ or not. I note that “Eternabond” tape was mentioned here in 2013 http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Roof-joint-sealing/32906/ but nobody seems to have tried using it. If the resealing of your vehicle’s roof-seals/rooflights has been carried out properly, using “Eternabond” tape as well should be unnecessary. Link to comment Share on other sites More sharing options...
Brian Kirby Posted May 11, 2017 Share Posted May 11, 2017 Tony44935 - 2017-05-11 1:31 AM Thanks for that, looking at my question again , I've got it wrong, is it a silicone, and think I've found that answer but my next question, are all sealants used on Motorhome roofs silicone based ??? Also if not how would I find out which are not ??? Thinking of using eye ndfbond tape to back up the seals already done, but eternabond will not stick to silicone. Cheers. Depending on what is leaking (assuming there is a leak and you're not just looking for belt and braces assurance), and further assuming that it is the sealant you suspect or know to be u/s, I'd suggest contacting the manufacturer of your motorhome and asking them to confirm what they would have used at that time. I know I've said this several times before, but modern sealants are a bit of a chemical minefield, with some products being pretty well the same thing, whereas others a sufficiently different that they react with one another to the detriment of one, or other, or both. "Silicone" also comes in various flavours, and in addition is "picky" over what it will bond to. It would help if you could give some information regarding what you want to seal, and why. Derek refers above to a rooflight, so I assume he has information I don't (again! :-)). If you have a leaking rooflight that was originally bedded on a non-setting type "mastic" (thousands were!), your best, most foolproof, remedy, will be to carefully remove the whole rooflight, carefully remove all traces of the original mastic from rooflight and van roof (you will need to experiment to find the correct solvent for the sticky mess it will leave (turps, meths, possibly linseed oil, even petrol of diesel, maybe carbon tetrachloride (doubtful)), and equally carefully remove all traces of the eventual solvent from both. Then use Sika 512, or a similar silane (usually :-)) modified polyurethane sealant (Locktite Henkel and several other manufacturers use the same, or analogous, chemistry) to re-bed the rooflight back onto the roof. Two caveats. 1. Don't screw the rooflight down so hard that all the sealant is exuded. It needs a bedding of about 3mm of sealant, and that needs to be allowed to fully cure for about 24 hours. Then go round the screws and just give each one about another 1/4 turn to lightly compress the sealant bedding. Should then do you for 25 years or so! :-) 2. The above is on the assumption that the item to be sealed is free standing, and not in contact with any other existing sealant (for example a roof seal or seam). If it is, finding out what the sealant original is will be critical to success, and you will need to verify compatibility to ensure long term durability. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted May 11, 2017 Share Posted May 11, 2017 Brian Kirby - 2017-05-11 4:41 PM ...It would help if you could give some information regarding what you want to seal, and why. Derek refers above to a rooflight, so I assume he has information I don't (again! :-))... In my last posting I provided a link to Tony’s earlier forum enquiry that mentioned resealing “sky lights”, but (Hey-ho!) here it is again :-S http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Sealant-for-the-roof/46990/ Link to comment Share on other sites More sharing options...
Ocsid Posted May 11, 2017 Share Posted May 11, 2017 Whilst a big fan of Sikaflex products and aware of their bonding capability exploited in vehicle structures, I would warn that if the thing to be fixed is a skylight you need to tread with awareness and care. Its exceptional "bonding" capability can make it less than ideal for anything that could need removing sometime down the line, ie and incident with a low tree branch or simply UV degradation of the skylight if owned for many years. It can't be "removed" other than mechanically, ie cutting through with a "cheese wire". That's fine if it is the type of application where a cheese-wire can be used. Can it on the skylight? Link to comment Share on other sites More sharing options...
Brian Kirby Posted May 11, 2017 Share Posted May 11, 2017 Derek Uzzell - 2017-05-11 5:40 PM Brian Kirby - 2017-05-11 4:41 PM ...It would help if you could give some information regarding what you want to seal, and why. Derek refers above to a rooflight, so I assume he has information I don't (again! :-))... In my last posting I provided a link to Tony’s earlier forum enquiry that mentioned resealing “sky lights”, but (Hey-ho!) here it is again :-S http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Sealant-for-the-roof/46990/ Ah. Didn't follow your link as I took it to be to a different (though related), topic. Link to comment Share on other sites More sharing options...
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