I can imagine two ways. First, on the very bottom, if you place the mug into a puddle of coffee, then no coffee will wet the bottom of the mug. Second, around the side, when coffee runs down the side of the mug, a hydrophobic coating might stop a drop in its path if it is not too heavy. Not sure if the second thing would actually work.
The coating around the side should form a V, with the handle being the lowest point, and make a little indentation on the bottom of the inside of handle to collect all the liquid...
I can imagine two ways. First, on the very bottom, if you place the mug into a puddle of coffee, then no coffee will wet the bottom of the mug. Second, around the side, when coffee runs down the side of the mug, a hydrophobic coating might stop a drop in its path if it is not too heavy. Not sure if the second thing would actually work.
The coating around the side should form a V, with the handle being the lowest point, and make a little indentation on the bottom of the inside of handle to collect all the liquid...
So make a GoreTex sleeve that waterproofs the bottom of your coffee mug?