Puraflex 40 difficult to extrude from nozzle

sealegsjim

sealegsjim

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I am using Puraflex 40 which is similar to Sikaflex (and made by the same company) It needs a lot of pressure from the gun and I notice that on the instructions it tells you to 'remove the baseplate' Anyone got any idea what the baseplate is on the tube of adhesive? Thanks
 
I have used tubes of sealant where the base of the tube has a removable cover/lid with a ring pull similar to a tin can. Could be something similar but then I would have thought it would be obvious if there was a cover on the end. Have you got a dodgy tube with partially cured sealant in the nozzle area? All the tubes of PU40 I have used have been fine unless the sealant has started to cure in the nozzle.
 
Some DIY shed guns are so lightly built that they're not able to push more serious substances out of the tube. Good for cheap bathroom silicone only.

Pete
 
sealegsjim said:
This was a new tube and nozzle but I take the point about feeble silicon guns
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I recently fitted two glass windscreens to my motorsailer using automotive techniques. The adhesive sealant was not a lot different from Sikaflex, just a little stiffer. Using a £5 Cox gun from Screwfix I was unable to squeeze it out with two hands. I then bought a £10 Cox gun, also from Screwfix, and the same tube was a doddle with one hand.
 
mmm, Mr Cox is recommending a Cox gun, perhaps a bit of undeclared interest!
I use PU40 a lot and there is no baseplate, just make sure the cartridge is fully pierced in the spout and the nozzle is clear.
Check the expiry date as they do go off after a while.
The main reason is probably the gun, these are 'buy cheap, buy thrice" tools.
I have bought many cheap ones and your hand gets very tired during big jobs and if you need to apply pressure due to thick sealants or old tubes then the gun can collapse. I have a lot of success with the Power Pro gun £10 Screwfix as it has barrel rotation, has a well geared trigger to exert good force without excessive squeezing and stops the flow very quickly on release. Keep the receipt as amongst the 5 star reviews there are quite a few one stars as the gun broke. Obviously if you are two-handed squeezing a sub-£10 gun the chances are it won't last very long.
My biggest headaches are: If you drop a new tube and dent the tube then you will have big problems as the plunger will jam in the tube. Also if a used tube hardens in the nozzle and the top of the cartridge then you can spend a lot of time clearing out with a nail and still have flow issues compared to a fresh tube. Keep a stock of new nozzles to save time and always leave a bit of sealant hanging out of the nozzle or cartridge to act as a plug to pull out next time. If the cartridge has been opened over 6 months it will probably have cured and will be dead.
 
The name of Cox sealant guns and my own is purely coincidental.

I find that squirting a little sealant out before screwing on the cap helps to preserve the cartridge rather better.

With older tubes there is a progressive path to recovery. First attempt is to push a small screwdriver down the nozzle of the cartridge to clear a small blockage of cured sealant. If this doesn't work do the same with a drill just smaller than the nozzle hole. Finally, if no success by these methods, punch a hole in the side of the cartridge.
 
PU 40 may have gone off that could be a reason for the difficulty in squeezing it out. Also it is not very UV stable, it seems to powder up easily if used on windows.
 
vyv_cox said:
With older tubes there is a progressive path to recovery. First attempt is to push a small screwdriver down the nozzle of the cartridge to clear a small blockage of cured sealant. If this doesn't work do the same with a drill just smaller than the nozzle hole. Finally, if no success by these methods, punch a hole in the side of the cartridge.
Click to expand...

I actually use the corkscrew on my knife. Screw in until it goes no further, then pull out hard. Usually gets the cured plug out and the liquid goop flowing.

And if the tube is completely cured through, don't throw it away. Slice it open and you have a cylinder of rubber to slice or punch flexible, waterproof washers, seals and gaskets from :-)
 
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