Can I have coffee and cake, on shabbos morning, on the same tablecloth that I ate the meat meal on the night before? Would it help if I place a small napkin under my coffee cup (but not under my cake plate)?
Answer:
If the tablecloth is clean, it can be used in the morning for coffee and cake. Placing a napkin or a saucer under the cup is a worthy precautionary measure.
Sources:
The Ramban (Teshuvot Ha-Meyuchasot Le-Ramban 172) writes that one should not use the same tablecloth for meat and dairy meals, as drops of grease and other residue often stick to the table. The Shulchan Aruch (Yoreh De'ah 89:4) rules accordingly.
However, the Pischei Teshuva (Yoreh De'ah 89:8) cites the Radbaz who explains that the Ramban referred to times when meat and cheese were placed directly on the tablecloth. Nowadays, however, when people customarily bring food to the table on plates, the Ramban's stringency isn't required, and may even be fulfilled by merely shaking out the tablecloth and brushing it off.
Therefore, the tablecloth from a meaty meal can be used for milky food, if all the food is on plates. However, as a precaution, it is a good idea to keep the coffee cup on a saucer or napkin, because the bottom of the cup can be wet with hot coffee, and this is liable to come into contact with an element of meaty grease on the tablecloth. If the tablecloth is clearly entirely clean, there is no real need for this precaution.