My process for using tung oil goes like this: If it is a new batch of oil and has good viscosity I will use it as is. If it has been sitting around for a while it may have thickened up so I will thin w/mineral spirits. I apply liberally and keep reapplying, watching the wood to see how it is absorbing the oil. I will do this for 20 minutes or more. Sometimes the finish gets a little tacky which is OK I will add a little mineral spirits to a rag and wipe of the excess till the wood is smooth. This process allows for good absorption. If the shop is hot (summer) the finish will get tacky pretty quick. Just use a little mineral spirits to the rag and wipe off excess. I found that I prefer the finish to get tacky, this is when it is starting to turn into a solid. I rub real hard to work the excess off. This is what a "hand rubbed finish" means - the heat and friction of rubbing dries the finish and produces a nice sheen