Is there ritual impurity if there is no visible color, substance, or smell?

If you touch something ritually impure (najis) that is dry, and your hand is also dry, then your hand does not become impure. However, if your hand or the impure object has wetness, then whatever part of your hand touches it becomes impure. If the impurity of the hand is confirmed, it must be purified, even if the trace of the impurity has disappeared but its ruling remains. If you doubt the impurity of your hand, the default is that it remains pure until its impurity is confirmed with certainty.