So that your mold takes hold without repelling any surface on a form or figure in wax, it is necessary to rub the wax with oil and soak your sand in lukewarm water, because cold water repels oil even more and will not make a good layer on the wax.
at left middle margin of folio 109r
Rub the oil on very very lightly, use so little that it hardly appears at all. Then rub with some spirits. After soak your sand in lukewarm water so that it does not repel the oil.