My use of "poor quality" referred to the workmanship of the ducks, Chris.
I'm not that fussed about materials, apart from what I can learn or deduce from their use.
da Vinci used materials quite different to those used today, which could perhaps could be described as being "cruder" or of "poorer quality" than contemporary oils and acrylics - but this puts no bad reflection on his work as an artist.
(actually, I think the old materials produced better colours).
Does anybody know if Mike Rayner, who knew Vicente Boffo, has been asked about the dates he was doing what in Malta? Somebody (Wolfie?) promised to ask, months ago, but there has been nothing heard since.