Which Sikaflex for holding something to the roof

[RichardB]

Hi all
I have a 4G aerial to fit on the roof - other than having to drill through with is rather daunting! I am not 100% sure which is the best Sikaflex for sticking it down and sealing around the edge of it. Ive got a tube of 221 and 512 - any recommendations which to use and why....
Thanks

 

[Mikeco]

I used 512 to stick my aerial down.

 

[tonka]

Toolstation. Puraflex 40

 

[AG 2602]

Just used 512 sets firm in a couple of hours!

 

[nicholsong]

With all Sikaflex products there is excellent information on their website.

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[G7UXG]

Dekasyl MS2 or MS5. It’s worked for me. Solar panel still attached (no screws used) after a couple of thousand miles.

 

[olsgreen]

512 will be fine. You could most probably get away with 221.

I am no expert but have done a lot or research into which adhesive sealants to use for what while fixing my van.

221, 512, 521 use different chemical bases or technologies if you would like. Each have attributes that lean towards specific uses. 512 shrinks much less than 221 and is faster to 'set' where as 221 is more elastic and has a higher shore hardiness, I could go on but best read the product data sheets. Sika recommend 512 for TV ariels in the document I've linked to right at the bottom of the post.

221 - <Broken link removed>
512 - <Broken link removed>

Before you apply the Sika make sure that you have throughly cleaned all services to be bonded, even if they look clean, preferably with isopropyl (rubbing alcohol) with a lint free cloth or even better use Sika Cleaner & Activator. Some plastics have a residue left on them after production which can cause bonds to fail (people often blame the Sika) Sika 512 bonds best at 2mm of thickness, so make sure you keep this amount of sealant in the joint. (i.e. don't apply too much downwards force on the joint and push all of the sealant out) Also, make sure the tube hasn't gone past it's use by date (printed on the side of the tube). A few months may be ok but more and I'd chuck it.

Another handy document on how to use Sika 512 here: https://gbr.sika.com/dms/getdocument.get/81048499-d15c-3eda-923f-148ccae8cd26/Sikaflex 512 Caravan.pdf

Good luck

 

[RichardB]

Thanks you all. 512 it will be.

 

[34127]

This might be of interest, it was sent to me by someone who found it on a different forum.


Always remember, where appropriate adhesives can be used to seal but NEVER use sealants to bond

Polyurethanes - Note: these adhesives are not great with UV stability so you will find white products exposed to sunlight may yellow in time.

Sikaflex 252 (adhesive) - The one most of you may have heard of. Used in conjunction with primers for bonding to many materials used in the make up of caravans.

Sikaflex 221 (sealant) - Again a popular (older) product used for sealing only and best used with primers. Also good for most materials.

Hybrid Adhesives (Known as Silane Terminated Polymers) - More modern and used in most caravan builds today. UV stable so can be used externally as well as internally.

Sikaflex 552 (adhesive) Can be used on most substrates sometimes without priming. Will bond most windows / vents / solar panels.

Sikaflex 521UV (sealant) Can be used to seal almost every joint on a caravan including external joints. Can be used around mechanically fixed items to ensure seal against water ingress if drilling or fixing into the body.

Sikaflex 512 Caravan (sealant) Similar to the 521UV product but has additional Biocides. In Laymons terms it has recently been reformulated to increase its mould resistance.

Butyl Sealants

Sikalastomer 710 (Butyl sealant) - Can be used as a sealant for parts that will subsequently need to be serviced and/or replaced.



Surface coatings, paint finishes Preliminary trials are necessary before attempting to bond substrates with an applied surface coating. As a general rule, reactive systems that cure thermally (cataphoretic immersion coatings, powder coatings) or by addition of polymerisation (epoxy or polyurethane paints) can usually be successfully bonded with Sikaflex® and SikaTack® products. Alkyd resin paints that dry by oxidation are not suitable for bonding. Paint systems that rely on a physical cure mechanism – typically coatings based on polyvinyl butyral or epoxy resin esters – are generally compatible with sealants only, i.e. not with adhesives. Caution: The presence of paint additives designed to modify film formation, such as conditioners, silicones, matting agents, etc., may adversely affect adhesion to the paint surface. Consider that certain coatings can be negatively influenced by wheatering, for example if exposed during transport prior the bonding and sealing process. Surface coatings must be monitored for consistency of quality and uniformity of composition through a quality assurance system