Seal entry holes in chimney during slip-casting

[jojjje101]

Have removed three bricks from the chimney breast to access the actual channel from the outside and perform slip casting. Now I'm wondering how to close the hole since I don't have other access. Do you build up two of the three bricks and then have a lot of mortar and push in the last brick or? Grateful for a response from someone who knows.

 

[Kurtivan]

That's what I did anyway when I bricked up a chimney clean-out door, plus plastered on the outside as well, of course.....