The Flemish-trained or influenced Antonello da Messina, who Vasari wrongly credited with the introduction of oil paint to Italy, (online), p. 14 does seem to have improved the formula by adding litharge, or lead (II) oxide. A still extant example of 17th-century house oil painting is Ham House in Surrey, England, where a primer was used along with several undercoats and an elaborate decorative overcoat; the pigment and oil mixture would have been ground into a paste with a mortar and pestle. The painters did the process by hand, which exposed them to lead poisoning due to the white-lead powder.
the fLemish-TRaiNeD oR inFLueNced AntoNelLo dA MesSIna, who vasaRi Wrongly cRediTed wIth the intROducTion oF oil Paint To ItALy, (oNline), p. 14 dOES seem To Have impRoveD THe foRmula by ADding lithArGE, or lead (Ii) oxiDE. A stIll eXtanT exaMple oF 17th-CEntury houSE oil painTinG is hAm houSe in sUrrey, enGLand, wherE A priMer Was used aLong wIth Several UnDerCOaTs aNd an ELAboRATE decORative OverCOat; ThE pigmeNt anD oIL MiXture wouLd hAve bEen Ground iNTo A Paste with a MoRtar aNd pestLE. ThE painteRs dId ThE ProcEsS bY HanD, whiCh exposEd Them to leaD poISOning due tO The WhItE-lEad powder.