Eldfast Lining

What’s the problem?

Over time chimneys disintegrate. Most commonly the midfeather (the cement holding the bricks of your flue together) crumbles to the extent that gaps allow fumes and smoke to leak from one flue to another and enter into other rooms (typically a bedroom above the fireplace).

While disintegration is natural, the process is often accelerated by the presence of soot as the acid in the soot eats into the midfeather. Having your chimney and flue cleaned regularly can help to minimise the effects.

What is Eldfast Lining?

The Eldfast lining is a ceramic paste applied to the full length of the inside of your flue. It’s made of two elements; a refractory ceramic aggregate in powder form and a resin bonding agent. These are mixed together to create a slurry that sticks under pressure and is resistant to acid condensation damage, thus protecting your chimney and flue.

A chimney flue prior to Eldfast Lining.

A chimney flue after Eldfast Lining.

The benefits of Eldfast lining versus stainless steel liners:

  1. With Eldfast no flue is too small. The paste is roughly 4mm thick which maintains the internal space of your flue.
    Stainless steel liners on the other hand, require sufficient space for the size of the liner, plus space to manoeuvre it in position. For example, lining a 9” by 9” flue for an open fireplace demands an 8” liner which only leaves 1” to manoeuvre the liner down the flue. The risk of damaging the liner is high which can significantly decrease its life span.
  2. Eldfast is long lasting and is guaranteed for 25 years. It can also last up to 60 years.
    Stainless steel liners are guaranteed for either 10 or 20 years and they almost certainly will need replacing within 30 years.
  3. Eldfast can withstand chimney fires.
    When a chimney fire occurs in a stainless steel lined chimney, a CCTV survey to access the damage will need to be conducted. In most cases the liner will then need to be replaced. Even if the liner isn’t damaged and thus doesn’t need replacing, after any chimney fire its guarantee will be void.
  4. Eldfast is leak proof.
    As stainless steel liners disintegrate over time they develop weak spots through which fumes can leak. These largely occur due to incorrect fuel use, irregular cleaning and improper fire burning.
  5. Eldfast is suitable for any fuel: smokeless coal, gas and solid, and doesn’t restrict what fuel can be used.
    However stainless steel liners do have restrictions therefore if you want to change your fuel you may need to change the liner as well.


How does Eldfast lining work?


A CCTV survey is required to ensure it is structurally sound, suitable for the application, and free of holes.  If there are breaches that are too large then remedial work will need to be carried out before the flue can be lined.


  • Your flue is cleaned with a wire brush to remove debris
  • The “plug” is deflated and lowered to the bottom of the flue where it is re-inflated
  • A small amount of Eldfast lining is poured from the top of the flue onto the inflatable plug
  • The plug is then winched steadily along the flue until the ceramic paste sticks to the sides
  • This is repeated until the plug reaches the top of the flue
  • One application is usually sufficient to leave a nominal lining of 4mm. Each application is checked and the process is repeated if the operator deems it necessary
  • The lining hardens via a gradual process of air curing which happens within roughly 30 to 60 minutes after application. The material will harden completely in just two days. A heater can be used to accelerate this process.
© Wight Initiatives
VAT # 218 3459 04
Registered in the UK # 7725 203
Wight Initiatives Ltd,
23 King Street,
Cambridge, CB1 1AH
The Officers’ Mess Business Centre, Royston Road, Duxford, CB22 4QH
Registered in the UK # 7725 203
VAT # 218 3459 04