Boiler Lagging

[Springbok]

There was a thread in a forum which I am trying to track down which mentioned a material that you could dampen and mould around the boiler or pipes I should have taken a note of it but as usual did not. I remember it saying builders merchants but went in and someone built like a ***** door said duh (just like homer) end of enquiry.

So can anyone remember what the material was !!!

Would help me greatly
Have a good christmas and new year