ideal caulk material for inside flue

[builder brad]

I am looking for the best material to fill some small gaps inside my ovens flue, where the entry tunnel joins onto the dome.

Part of my flue is made up of a really tight firebrick arch with a filler made up of firebrick dust, sharp sand and cement which has set perfectly, but seems to heve shrunk slightly leaving a gap. I looked at the high temp silicone but its only rated to 350 C. I could use some of the firebrick dust and cement although I think that wont work as its too gritty for the gaps.

any ideas?

Brad

[ThisOldGarageNJ]

hi brad,
Refractory Mortar, Sealant 3200 degree 11 oz. tube - eBay (item 130281708457 end time Apr-15-09 15:05:32 PDT) paste this in your browser. It is an ebay item for 3200 degree caulking, it comes from an ebayer name High Temp Refractory Store. Its about 20.00 an 11 oz. tube with shipping,, Good luck, Mark