Yes I know but only problems I have had with Terracotta the past is if I have used Resin type sealers - used to fix a fair bit for Paris Ceramics - what a licence to print that was - just that type of Terracotta Pammet you show they are problematic feckers from an efflorescence point of view - a couple of fixers we passed work to where using yacht varnish and I remember a couple of problems they had with efflorescence coming up underneath - how to get the varnish off?! I think they used wire wool and nitromors - not nice.
Anything I finish Terracotta with, must have a remover that will take it off. Double Boiled Linseed has always served me well, and can be thinned with genuine real Turpentine will post a pic in a minute also LTP antique oil and finished with antique brown briwax