Perhaps the most popular method of raking is a technique referred to as scrubbing. It can be used with nearly any shape of pick. It is also the technique that many find the most difficult to master, when all subtleties are considered.
To begin scrubbing, insert the tension wrench into the lock and grip a rake of your choosing with the pencil grip taught earlier in this manual. For the time being, this lock should not contain any security pins, and it is preferable to minimize the high/low combinations. Insert the pick into the lock, under the pins, parallel with the bottom of the keyway, making an effort not to lift any of the pins. While applying very light tension, begin to gently saw the rake back and forth under the pins, at first making only very gentle contact with the key pins. While maintaining tension, and continuing the sawing motion, begin to raise the pick up in the keyway slowly, gradually lifting the pins higher as you go. If the lock has not opened within about a full minute or so of scrubbing, begin to seesaw the pick, tilting back and forth, all the while continuing with the back and forth sawing action. The purpose of this action is twofold. By tilting the pick slightly forward and back in a seesaw motion, it changed the shape of the pin with respects to the way it contacts the pins. This can help to set pins that were out of reach while the pick was aligned on the horizontal plane. With a little luck and some practice the lock will open.
The principle on which scrubbing relies can be purely explained by physics. As tension is applied to the lock, the binding effect will cause one pin to bind at a time. The gentle force being exerted on the pins is just enough to overcome the drag caused by the binding effect, without being enough to push the binding pin past the shear line. Once a pin sets, the binding force is transferred to the next pin in the binding order and the process is repeated. It is possible, in some cases, for the lock to open after only a couple passes with the rake. Though these results should not be expected, they come as a very pleasant surprise.
The biggest challenge one faces when using the scrubbing technique is that of getting the required amount of tension correct. Because raking techniques inherently lack the user feedback of single pin picking, it is difficult to know when a pin has been over-set. If too little tension is applied, the amount of force required to push a key pin past the shear line and over-set the stack is too little, cause frequent false sets. Also, if too much force is used through the scrubbing process the same can occur. If too much tension is applied to the lock the binding pin will not be pushed upward by the gentle scrubbing action, and no pins will set. Practice this technique fully to acquire the skills, then refresh your technique often to maintain.
Scrubbing will allow you to open many locks in a remarkably short period of time. It is recommended, however, that if scrubbing is not successful in the first two minutes, it will probably not be. At this point, change picks, revert single pin picking, or try an alternate raking technique.