Description Good on Black Hard Rubber AND Mixed/Mottled Hard Rubber pens. This formula is a liquid. Not sticky. Go ahead and let it get inside the barrel. It will pour right out. Wipes right off. The rest evaporates. Won’t leave any gunk on levers, pressure bars, or under clips! Super easy to use. It deoxidizes! It cleans! Gets old dry ink out of vintage pen caps! A lot of the oxidation will come off into the solution. Wait 1 hour for an ordinary oxidized black hard rubber pen, or several hours for badly oxidized pens. *Mixed red/black hard rubber – we recommend 5-10 minute soak* After soaking, remove pens/parts. Rub pen parts firmly with a rag to remove adherent oxidation. We recommend shop towels. A little friction and a firm hand really help. Fluffy cloth does not work as well. Feel free to repeat the process for another couple hours, or even overnight on black hard rubber pens! After firmly rubbing with a shop towel, polish with your favorite pen polish. Even better results are seen if you finish it off with Dr. G’s Clean & Shine Pen Rejuvenator. BUT WAIT!!!! THERE’S MORE!!! After all, this is NOT JUST DEOXIDIZER. It cleans as it deoxidizes! Just throw in the cap! Feel free to take the cap off and throw the cap in the bottle. Or, if you don’t want to get the rest of the liquid all inky, pour a little into another container and add your cap. Let the cap fill with "not just deoxidizer". The solution will clean all the old, dried ink out of the inner cap as it deoxidizes the surface! After 30-60 minutes, take out the cap and pour the solution back into the bottle so you can use it again (or discard if the color bothers you). Clean inside the cap with a cotton swab. For celluloid and acrylic, give it a quick rinse with water. You have never seen a cleaner inner cap with so little effort!!! Restoring an old pen? Just throw in the barrel!!! No need to plug the barrel with cotton. No need to keep the cleaner out of the barrel. Let it fill with Dr. G’s "Not Just Deoxidizer." It will clean grime and ink from the inside of the pen at the same time the outside is being deoxidized. Do not soak celluloid overnight, but 30 minutes is not a problem. NO GUNK TO GET STUCK IN THE LEVER OR OTHER PARTS. We offer Free Shipping on all orders over $59 for US customers, and for orders over $250 for our Canadian customers.