3,481. Demai Oil on One's Skin; Rectifying Produce Improperly

Hilchos Maaser 13:18

If demai oil falls onto someone’s skin, he may rub it in without concern. If someone buys wine to put in fish brine, or if he buys diluted wine or pulse to crush and mix into honey, the rules of demai apply. However, if he bought fish brine that contained wine, or a mixture of wine and oil, or a mix of crushed pulse and honey, the rules of demai don’t apply. This is because Chazal didn’t institute demai when the produce is mixed with something else. If the demai produce that got mixed with other things was something like spices or yeast, then the rules of demai apply to the entire mixture because the presence of the demai ingredient is obvious.

Hilchos Maaser 13:19

In all cases where demai doesn’t apply because Chazal didn’t require it in such circumstances, if one rectified the produce as demai, i.e., he took terumas maaser and second tithe, his action is effective. If he tried to rectify demai as one does produce from which we know that tithes were not taken, i.e., he took terumah gedolah and tithes from it, or if he tried to rectify produce from which we know that tithes weren’t taken by acting as one does for demai, his actions are ineffective.