can anyone recommend a sealant that will is for brake systems, if there is such a thing...

an extra 1/4 turn on the spanner?

or remake the pipe with a better flare on it.

(sorry i realise thats no help, but the sealants for cooling systems are a bodge, i'd be really nervous using a bodge on my brakes).

No such thing.........only good mechanical engineering.

As already stated - no such thing.

Mainly because you don't want to risk bits of sealant floating around in the system blocking up all the very small orifices in the master cylinder and brakes.

maybe this!!

if it's for pipework might be worth a look (though might not work if the joint is already leaking and if you've going to take it apart to clean it you may as well rebuilt it new!!!)...