Having recently replaced my toilet I have found the pipe leading to the main stack loose.

The pipe is pitch fibre and joins onto a plastic elbow wich goes straight into the main stack.

What is the best way to fix and seal the pitch fibre pipe to plastic elbow?

Having recently replaced my toilet I have found the pipe leading to the main stack loose.

The pipe is pitch fibre and joins onto a plastic elbow wich goes straight into the main stack.

What is the best way to fix and seal the pitch fibre pipe to plastic elbow?

Good morning Sean,

You're describing Orangeberg Pipe. Something I haven't used for over 40 years. If this were my call I would tear out all the old Orangeberg and replace it with PVC.
But that wasn't your question was it? You asked, "What is the best way to fix and seal the pitch fibre pipe to plastic elbow?
I'm assuming the pipe seats into a hub in a PVC or ABS elbo.
I would make a caulked lead and oakum joint, only instead of using melted lead to pour over the packed oakum, (that could melt into the pipe) I would use lead wool as a substitute and caulk that instead. Good luck, Tom