...My son's Italian girlfriend grew up with her Mum and her Granny making all the tomato sauce for the entire family for a year in an enormous cook in over a few days at the end of the growing season. I'm told that they just used every sound jar and bottle they could get hold of, never ever bought those fancy 'seals', and no chemicals bar salt, sugar, spices and herbs. A bad jar/bottle is virtually unheard of. That's commonplace too.
Good basic cleanliness, good hygiene and careful production.....bit like our jam making really