I did some inking on coffee mugs. Ink is a little different from paste. Firstly, once it is heat set it is permanent. So really it is better to use ink on fabrics, because they can be laundered then. Secondly, the ink has a creamier consistency. Thirdly, the ink dries a little slower than the paste.
I used the Geo Cat transfer and Regal and Couture Coral ink, as well as the Multi-Tool. Using a transfer on a curved surface is a bit fiddly so I made sure that the screen part was completely adhered down but didn’t worry about the rest of the transfer. I also used the multi-tool to apply the ink exactly where I wanted it.
After the mugs dried completely I baked them in my oven for 30 minutes at 350 degrees. Now they are heat set and dishwasher safe.
The ink is not FDA approved so you don’t want to use it where it will come in contact with your food, but on the outside of a mug is fine.