You know how it goes you get a puncture or disrail a chain and have to fix it. When you have finished your hands are full of dirt and oil. You rub them on grass at the side of the road to try and get it off.
Get yourself a pair of disposable gloves the latex ones are best. Put them on before you start, take them off when you have finished. Clean hands. They are very small, you can roll them up and keep them in your tool bag ready for when you need them.
