Baumgartner Restoration, again

Though, as the more tedious politicians say, "I make no apologies for returning to this" (some of them really ought to learn the virtue of apology, did they not...?  But let us stick to the point) - but I've been looking at Julian Baumgartner's restoration videos on YouTube.  Perhaps they're of niche interest, but then I find the most fascinating things often are. He has transformed, expertly, some fine paintings - most of them probably wouldn't have been thrown out; there were good reasons to think they could be saved, as indeed they were.  But there is a video in which a painting on canvas of the Virgin Mary, painted some time in the 15th century I think, which came to him in three pieces - THREE sections, torn straight across.  I would have assumed the painting was fit only for scrap; you might have kept the bits as historical curiosities, but surely you wouldn't attempt to restore it.  Yet - he did.  He did an almost incredible job: lining the old canvas, filling in the holes, hiding the tears, replacing the paint that had chipped away, removing the old, bad overpainting.... I was transfixed by this video, with his expert narration as well; I had no idea that such work was even possible; then he ends the video by telling us this sort of work is his favourite ....  I won't put in a link this time, you'll find him if you go to YouTube and type in Baumgartner Restoration: and you really should, if you've any interest at all in the history of painting, the possibilities of restoration - and why we should never, ever, try to repair someone else's painting without the quite extraordinary expertise and professionalism which JB brings to his work.   Incidentally - watching these and other videos has made me even more cautious about cotton duck canvas: these paintings were all done on high-quality linen - if you're good enough for your paintings to sell and attract admiring looks, you do owe it to yourselves to ensure - if you possibly can - that they're on linen, if you use stretched canvas.  This material has lasted, sometimes in astonishingly good condition, for centuries: it's generally bad handling, dirt, lack of care, that has led to their degraded state - not only the passage of time.