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Sikaflex 512


John H

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Posted

We have had a leak in the roof of our van for some time now. I took it back to the place we bought it from and I thought it was fixed but it happened agan when we were in France.

 

It only happens when the van is sloping forward when I assume a pool forms where the low profile cowl joins the flat roof. When it's parked on the drive outside the house, it never happens but the van is sloping bacwards.

 

I ordered some Sikaflex 512 from Roadpro the other day and I hope to attempt to fix it before we go to Scotland on the 19th. Does anyone have any tips on the best way to apply it or know of any likely problems to watch out for. I've got a caulking gun but I was wondering if when it has been applied, can you finish it off with a wet knife or finger.

 

I would be grateful for any tips from anyone because I tend to start things and read the instructions later. :$

 

John.

Posted

I have heard many good words on Sikaflex but the most important is the preparation. Cleanliness is paramount. Its frequently used to bond solar panels and Satellite dishes to the roofs of motorhomes, so it should be strong. READ THE INSTRUCTIONS FIRST. OK!

C.

 

Posted

Hi John H,

Sikaflex is a very good sealant/ bonding product I used it when I fitted my Max View sat dish.Have a good look at the area that you suspect is leaking, clean around the area with spirit or acetone to provide a key for the sealant. Cut about a 45 degree angle on the plastic nossle then using your mastic gun run along the seam making sure you get it well into the joint. you can smooth the surpus using a wet spatular or as I do a wet finger!

 

Geoff

Posted

I 've got a pair of chest waders and the boots were perished beyond salvation. I cut the old boots off and bought a new pair of wellies.

 

Using Sikaflex 512, I bonded on the replacement boots to the uppers and they do not leak a drop.

 

So, top that !!

 

Perhaps a new thread...uses for Sikaflex 512 !

 

 

 

Posted

now tell fred whats the difference between a bonding product and a sealing product, eh my biddies? Surely (or so denzil says) you need a sealant, unless you intend to seperate panels and rebond em. if the leek still persists it will be one hellava job to remove the bonding stuff.

 

fertilizerfred

Posted

I have used silkaflex for several little and large jobs, including replacing the roof lights. I always manage to smooth mine out with either a wall paper scraper knife or my fingers. For best results in cleaning up after, use WD40. this cleans up no problems. Do not use it on the area you are about to seal though as this can prevent sealent. Just as others have said give thearea a good clean and get rid of any old residue.

Good luck.

Posted

John H:

 

I've got a SIKA product-leaflet for Sikaflex-512 Caravan that I picked up at a NEC Show a few years back. This leaflet describes how best to prepare the surfaces to be sealed/bonded, which cleaning agents to use, how to achieve a strong bond, etc.

 

Suggest you ask SIKA for a leaflet via sales@uk.sika.com or tel: 01707 394444

 

There's also a pdf relating to Sikaflex-512 Caravan on:

 

http://tsw-comsat-sales.co.uk/images/File/Sika512caravan-etds.pdf

 

(For what it's worth, I was once advised that obtaining a super-smooth final finish when using this type of adhesive can be achieved by rubbing the adhesive's surface with a cut potato. I was told that this method was employed on boats when the adhesive was used to seal decks. However, as I've never had occasion to try this, I can't vouch for its effectiveness.)

Posted

Thanks to everyone for their advice. I feel a bit more confident about having a go at it now.

 

Derek, I think I will give your potato suggestion a go. It seems like a great idea to me.

 

Thanks again,

John.

Posted
John H - 2008-08-02 4:17 PM We have had a leak in the roof of our van for some time now. I took it back to the place we bought it from and I thought it was fixed but it happened agan when we were in France. It only happens when the van is sloping forward when I assume a pool forms where the low profile cowl joins the flat roof. When it's parked on the drive outside the house, it never happens but the van is sloping bacwards. I ordered some Sikaflex 512 from Roadpro the other day and I hope to attempt to fix it before we go to Scotland on the 19th. Does anyone have any tips on the best way to apply it or know of any likely problems to watch out for. I've got a caulking gun but I was wondering if when it has been applied, can you finish it off with a wet knife or finger. I would be grateful for any tips from anyone because I tend to start things and read the instructions later. :$ John.

A few thoughts:

First, have you covered the suspect joint with Duck tape, or similar, to a) test that you have identified the correct location and, b) to (hopefully) prevent further ingress until a proper repair is made?

Second, I note from Derek's link that Sika do not mention plastics as a suitable substrate for 512 Caravan.  It might be wise to check with them before you start.  Note that Sika say once the stuff has cured it can only be removed "by Mechanical means".  That is shorthand for it is very difficult to get off, so if it doesn't adhere properly to the fibreglass elements, you'll have a hell of a job on your hands!!

Three.  Don't start before you've read in instructions, in fact, don't start before you speak to Sika and get, and read, the data sheet for 512.  While speaking to them, ask about how to finish the joint (they say do not use solvents, which should rule out Rainbow Chaser's cellulose thinners!), and get a copy of the COSHH sheet on the product as well.  I doubt it is hazardous to use, but these are industrial sealants, and you never know!

Modern industrial sealants are chemically complex products, usually designed for particular jobs, seldom being universal in application.  They must be stored and used as directed, or they tend not to work as they should.  Used correctly, they are superb, but once you've puffed and sworn you way along the old joint to remove all the old sealant, and than cleaned it all up, the last thing you'll want is for the new joint to fail in short order because of some minor oversight.  Done right - which I assume someone at Elnagh didn't manage - that joint should last for years!

Finally, you'll save yourself a lot of trouble if you run a strip of masking tape either side of the joint before you apply the Sika, smooth off the joint surface (noting you have only 30 minutes before it becomes tacky) and, before the Sika starts to cure, carefully pull away the masking tape with all the overspill attaching to it.  Don't chose a windy day though, unless you want to end up wearing it!

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