POM: proof of mastic ())
Glazing , or infiltrating mastic ( calcium carbonate, linseed oil mixture ) in order to weatherproof the stained glass has also the benefit of augmenting its overall rigidity .
https://blossom.primal.net/2d8daab72e4f7e1aa3eb9baa7baf7d9c38e6b84dabfd45ce5ee5965c7d4318ce.mov
