Sikaflex 291...storage after opening?

Greenheart

Greenheart

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I congratulated myself on how much cheaper Sikaflex 291 is, bought in a 300ml cartridge, than when bought from the same store in a 100ml toothpaste-style tube.

But the work I bought it for will have to take place in two parts, some days apart - possibly longer...

...has anybody found that it rapidly hardens up inside the cartridge after opening? Or are there ways to prevent or slow its hardening?
 
Sure does harden as soon as air gets to it.
Seal the end of the tube really well - cling film and tape - then put it in the freezer.
I always buy the small tubes - less to throw away
Good luck
John
 
Thanks for this...how soon after opening must it get in the freezer? I anticipate needing a lengthy period - let's say 90 minutes - after opening, while I mould it into the cracks.

Add a while longer to get the opened cartridge home...and the current very warm weather...

...can I assume the curing process creeps up the cartridge from the opening? So, I might lose an inch or so at the top end of the cartridge before I put it in the deep-freeze...

...but, I could drill through the cured section, to use it again at a later date. Or...does the cure affect all of the contents after opening, thus it needs freezing almost at once?
 
I find it is perfectly useable for a week or more after opening, sometimes needing a poke with a small screwdriver or a wire to clear the nozzle tip. After a few weeks some attention with a drill might be needed.

You may find that PU40 from Toolstation is a more economic way of buying. Less than half the price of 291 and the same stuff as far as I can tell.
 
Speaking as one who doesn't have a freezer (and the ineffective vertical ice-making thingy in the ineffective westerly fridge is too small) you may be over-worrying. Over "some days" or even "some weeks" your biggest problem will be the solidifying in the nozzle (why can you never buy spares in chandlers? Yes I save my old ones but can rarely remember where I put them). When it's really solid it obviously comes out easier. The cartridge it's usually just a case of excavating a centimetre or two with an old thin screwdriver. Get to "some months" and it's game over, although determined excavation can usually yield enough for a repair you really need to do.

EDIT: Also...I don't find that putting cling film over the top of the cartridge is better than just keeping the nozzle on. Possibly worse.
 
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Wrap just the nozzle of an opened 291 cartridge in 2 layers bacofoil.Squeeze out a little into the foil to 'bed' the end.Clean the nozzle end before use again.Lasts a long time.
 
Some days apart is no problem - you could probably put the tube down unprepared and still resurrect it a week later.

My technique is to unscrew the nozzle, apply a couple of small pieces of tin foil over the end of the tube, and screw the nozzle back on to hold the foil in place. The foil generally comes from my sandwiches during a winter work session! When next needed, I remove and discard the nozzle and foil, and screw on a new nozzle from the bag of 100 or so I bought on eBay years ago. This works fine over a three or four month refit period. I wouldn't rely on it to work from one season to the next.

Pete
 
I actually have a spare nozzle from another mastic cartridge, bought before reading its unsuitability for marine purposes. So...I'll hope to take the Sika nozzle off when I use it the second time...thereby discarding the bit that will have cured hard...and fit the other, new nozzle, possibly also giving the contents of the cartridge a penetrative dig at the top.

Thank you gentlemen. I might even launch, this season. :encouragement:
 
Mine lasts all season! I use a bit of plastic shopping bag over the screw thread and then put the nozel back on for longer term storage (if I'm not using it in the next day or so) or just insulating tape wrapped found the end.

Worst case is remove the nozel and use a screwdriver to clean it then remove the plastic bag and use. Sometimes I have to poke the tube with a big screwdriver to open it.

Wven worse case and I've used a tube from the previous year is you just forget the nozel, feel the tube for the soft spot and use aforementioned big screwdriver to stab the tube. Squeeze and it comes out. A bit messier but still works. Tape it up with insulating tape once finished and repeat further down the tube next time you need some.
 
On the side of the box that I keep my (mostly silicone) sealants in at home, I have a bulldog clip. Clipped into it are dozens of 5cm squares of polythene sheet. Put sheet over end of cartridge, screw on clean nozzle. Stick a 75mm nail in the used nozzle and leave to cure, when cured pull nail to remove plug and discard.
 
Similar to ctva's screwdriver, I use stanley knife to cut out strip along side of tube (fingers) then scoop out with screwdriver, then tape up with insulating tape.

This method also shows you how much you would have thrown away.
 
laika said:
Speaking as one who doesn't have a freezer (and the ineffective vertical ice-making thingy in the ineffective westerly fridge is too small) you may be over-worrying. Over "some days" or even "some weeks" your biggest problem will be the solidifying in the nozzle (why can you never buy spares in chandlers? Yes I save my old ones but can rarely remember where I put them). When it's really solid it obviously comes out easier. The cartridge it's usually just a case of excavating a centimetre or two with an old thin screwdriver. Get to "some months" and it's game over, although determined excavation can usually yield enough for a repair you really need to do.


EDIT: Also...I don't find that putting cling film over the top of the cartridge is better than just keeping the nozzle on. Possibly worse.
Click to expand...

http://www.ebay.co.uk/itm/Spare-Noz...t=LH_DefaultDomain_3&var=&hash=item3381dcc3e7
 
After working in the PU industry for 28 +years I thought I was smart as far as PU was concerned. I even worked on products similar to these Sika ones. My personal attempts to prolong the usefulness of these moisture materials once opened are less than successful !

Freezer; yes, but my wife objects
In a sealed bucket with silica gel; they still cure
Freezer with silica gel; my wife objects even more.

The solution is the small tubes they sell in America in places like Walmart; but only attractive at American supermarket prices !
 
Thanks for these pointers. I used about one third of the 300ml cartridge this evening and did some satisfactory work, sealing-in the bases of my new cockpit-to-transom drains...

...before...View attachment 44205 ...and after... View attachment 44203

But I think my pump is a pretty rotten one. Just a sad little squirt of Sika, for several tiring squeezes of the handle. Really hard work, used at arm's length under the rear deck.

I found that the spare nozzle I had for a different mastic cartridge, has a quite different thread on it. So I don't know how well I can attach it for the next stage; but as long as the nozzle doesn't pop off, I reckon I'll manage. The next stage will mainly involve smearing a thick bead of Sika round the ply bulkhead I've made to re-close the cutaway section.

The Sika is in the freezer, with a bit of thick polythene over the open end and the old, full nozzle keeping it there. I know, I know I'll wish I'd done as was advised here... :rolleyes:
 
Yup, that one looks more like the business, as one would expect at a tenner or more. I like the way those aren't available to under-18s, even without a cartridge. :rolleyes:
 
I finished the Sika 291 cartridge this evening, and it was still thoroughly gooey even in the tip of the nozzle.

Despite using rubber gloves, I managed to get a lot on my hands, and it's the devil to shift.

I now have 200 empty lemonade bottles wedged, epoxied and Sikaflex-sealed into the voids in the hull. :rolleyes: I'm not actually expecting catastrophic leaks, but I reckon she's effectively unsinkable, short of being run down. :)
 
dancrane said:
I finished the Sika 291 cartridge this evening, and it was still thoroughly gooey even in the tip of the nozzle.

Despite using rubber gloves, I managed to get a lot on my hands, and it's the devil to shift.

I now have 200 empty lemonade bottles wedged, epoxied and Sikaflex-sealed into the voids in the hull. :rolleyes: I'm not actually expecting catastrophic leaks, but I reckon she's effectively unsinkable, short of being run down. :)
Click to expand...

Why do you not put a note in each bottle with " Help" written on them so when you do get run down any escaping bottles will eject & eventually someone will know to call the RNLI. Save on the cost of an EPIRB

Next time you do some sikaflex joints get a putty knife & grind the point to a radius
You will find that the straight edge will pick up the excess mastic on one face & leave a nice radiused bead then if you return the stroke with the flat on the other side it will remove the rest. The size of joint being determined by the radius you put on the point
Some of the excess can be re applied further along as the flat edge makes it easy to place the mastic & wastes less
Far better than fingers or bits of stick
 
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