I kinda stumbled upon this technique while the adding finish to the bodies and necks of the guitars I've built.
You will need a piece of cloth which should be mostly, if not all cotton. An old t-shirt cut up works well. Some wipe on poly finish, such as Minwax brand, or some wipe on Tung oil finish. Both work well. You will also need some odorless mineral spirits (OMS). Wet the cloth with OMS making sure to get it completely covered, wring it out and lay it on a flat, clean surface such as a fresh peice of foil. Drizzle a decent amount of the finish on it. Both the Poly and Tung oil finishes, when wet, disolve in the OMS. Now kind of work the cloth around to try to get the finish as evenly distributed through the coth as possible. Next rinse the cloth in hot running water and lay it out to dry. The finish will dissolve in the OMS and impregnate the fibers of the cloth, then cure, not "dry" actually to lock in the loose fibers and impart a mildly abrasive quality to the cloth. Because the finish cures, not dries, adding more OMS will not dissolve the finish from the cloth. Niether will lacquer thinner or alcohol. There's probably nothing you could put on the cloth to dissolve the finish, especially with the poly that won't also dissolve the cloth. The cloth will be stiff, but if wetted will become more pliable. You can repeat the process to add additional stiffness abrasiveness to the. Using different types of cloth should result in more abrasiveness. You can polish the crap out of stuff with these in no time and they seem to leave almost no visible lint.
This may or may not work. I can't comment as to the effectiveness of this idea. If it has worked for you, great.
However, oily rags can and do spontaneously burst into flame. Most shops have a fireproof can to place oil soaked rags in until they dry cure. At that point they are essentially inert. But while curing there is always the chance of something bad happening. If someone wants to try this technique they should be advised that there is the potential for a catastrophic problem. Make sure the rags dry in a fireproof place.
First of all, welcome to the board, and thanks for the words of caution. A single cloth laid flat probably won't spontaneously combust. The problem with oily cleaning rags is when they are wadded up and piled on top of one another which will cause heat from chemical reactions to build up resulting in a potentially combustible state. Heat can easily escape from a single cloth, moreover, using this method, it's soaked in water. I have and do regularly use these cloths to apply both types of finishes mentioned, always washing with water and laying flat or hung flat over the edge of a basin to dry. I too would caution against wadding the rags up and piling with other used, oily or dirty rags for the exact same reasons as stated by 202dy. Thanks again for the heads up.