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Product Details

Fast acting silicone paste which is used as an effective external leak sealer and jointing compound.

Technical Specification
Brand Fernox
Safety Data Sheet click here
Volume (L) 0.05
Delivery details
Order value: Under £10 £10 & over
Express usually Next Business Day before 6pm
Due to temporary service restrictions our estimated delivery time is currently 2-3 business days
£5 Free
Turbo usually Next Business Day before 12 noon Temporarily unavailable £10 £5
Remote areas standard delivery (2-4 days) £5 Free
Order Value: Under £25 Over £25 but less than £75 £75 & Over
£10 £5 Free

Please note items delivered by our suppliers are not available for the options above. Delivery times may vary.

More about Delivery & Returns
Click & Collect details
If you are using our Click & Collect service please note the following:
  • Order online or over the phone and collect in branch from 5 minutes later.
  • Ensure you check stock is available for collection at your chosen branch.
  • Check branch opening hours to ensure you have sufficient time to collect.
  • For items not available for same day collection, place order before 9pm Mon-Fri (4pm Sun) and you can collect Next Business Day (Mon-Fri) after 3pm.
  • If we have your mobile number, we’ll send you a text when your order is ready to collect.
Fernox LS-X External Leak Sealer 50ml is rated 4.7 out of 5 by 21.
Rated 5 out of 5 by from SEALER fernox useful sealer for toilet connection
Date published: 2020-03-17
Rated 5 out of 5 by from When Nothing Else Works ......... My review of this product will echo another customer review but I'll give a little more detail on what I tried before turning to LS-X. I had a leaky radiator valve thread that I tried about 7 times to resolve without success. First I tried about 5 laps of PTFE tape, then 8 then 10. I then tried Fernox White Hawk by itself, then with 5 then 8 laps of PTFE tape all without success. In between these attempts, I changed the valve also. I then cleaned all the threads and tried the LS-X. It looks and feels like silicon to be honest. I smeared a fair amount on the thread and tightened it up. The instructions advise that it takes 2 -12 hours to set. Not wanting to take a chance (as my next step was to buy a new rad) I left it overnight so around 24 hours. Welllllll it actually worked. System has been pressurised for 3 days now and still fine. BRILLIANT STUFF.
Date published: 2020-03-17
Rated 5 out of 5 by from Worked a treat! I bought this a couple of days ago to temporarily repair my daughter's leaking cold water tank. It was easy to apply and worked well. Note that the instructions recommend leaving 2 to 8 hours to cure.
Date published: 2020-02-29
Rated 5 out of 5 by from Simple to use and effective I used this when fitting a new basin click waste - a ring of Fernox between the rubber washer under the basin and the basin made a perfectly watertight seal. Simple to use (with some sort of protective gloves on!) and effective.
Date published: 2020-02-02
Rated 1 out of 5 by from Did not do what it said on tin Do not waste your time and money. Service at Tool Station service was great though and item was best price I could find but turned out to be a waste of time and money.
Date published: 2020-01-12
Rated 5 out of 5 by from Well worth using I have used this for many years on plumbing jobs. Compression fittings can be sealed first time every time. It also makes it easier to dismantle fittings for maintenance many years later.
Date published: 2020-01-01
Rated 5 out of 5 by from A good and well known product. I have beee nusing this material for over 25 years and use it for all compression joints to lubricate and seal. It ensures leakproof joints without excessive force to tighten. I do not know why it is described as an external leak sealer, I think you would need to be very lucky for it to work.
Date published: 2019-12-02
Rated 5 out of 5 by from FERNOX Leak sealer Always have used this stuff its great!!
Date published: 2019-11-28
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