In its flaccid state, an individual's penis varies in size depending on conditions such as temperature, underwear type etc. On some individuals, this variation is significant, while on others, it is much less.

Circumcision must remove an amount of skin which will yield the desired cosmetic results throughout the various flaccid sizes. This is especially true for partial circumcisions where a small variation in removed skin can yield a significant difference in appearance.

It is therefore important to understand how the skin on the penis works.

SKIN LENGTH FORCE

The skin, being elastic, has a natural state, a compressed state and a stretched state. In its natural state, the skin exerts no force.

As the penis grows, the skin becomes stretched and thus exerts a force pulling any skin towards the pelvis.

As the penis shrinks, the skin becomes compressed and exerts a force, pushing the skin towards the tip of glans.

CORONAL FORCE

Because the shaft skin is narrower than the diameter of the coronna of the glans, it will resist moving over coronna toward the tip until the skin length force surpasses the force needed to stretch the skin's diameter.

In the other direction, skin that is on the coronna will have the tendency to slide back on the shaft because its elastic property will move it towards a smaller diameter.

FORESKIN OPENING FORCE

Similar to the coronal force, the foreskin opening force will have a tendency to place the tip of the foreskin at the most narrow position. The smaller the opening, the more skin length force will be needed to compensate for the force needed to stretch the opening. Similarly, the smaller the opening, the more

In a moderate or loosely circumcised penis, during the flaccid state, the skin on the shaft has some level of compression and hence a desire to expand. However, the force to make it expand is smaller than the force required for the skin to stretch to go over the corona. As a result, the skin usually stays "bunched" up against the rim of the glans to a varying extent.

After circumcision, over time, because the shaft skin will not have its diameter stretched regularly, it will require greater force to make it go over the rim of the glans. This also happens to uncircumcised males who keep their foreskins retracted all the time.

Circumcision changes the length of the skin on the penis, and thus changes the skin length force. Studying the effect of the "physics of the foreskin" is very important if you elect a loose or partial circumcision.

Not only is the length of the skin changed, but the foreskin opening force is also greatly modified with most circumcisions. A long foreskin has its tip narrow in its natural unstretched state and has the ability to stretch greatlty. As you retracts the foreskin slowly, the normall small opening is stretched, giving an increasing resistance to being retracted.

After a partial circumcision, you are left with the tip of the skin whose natural diameter is closer to the diameter of the rim of head and hence, for the foreksin to retract behind the rim, the foreskin opening force will be smaller since it need not stretch as much.

In the uncircumcised with long foreskin, partial erection can often be acheived without much of the glans being exposed since the foreskin length force is smaller than the foreskin opening force. Thus there will be a certain amount of tension on the foreskin length, a force balanced by the resistance of the foreksin opening to widen.

However, in a partially circumcised penis, because the foreskin opening force is very small, any change in the foreskin length force will result in the foreskin moving back. Thus, even at the onset of erection, the remaining foreskin will begin to retract. This becomes a significant parameter when deciding how much skin must be removed, especially for male whose penis varies greatly in size between the totally flaccid state and the fully erect one.

Similarly, for loosely circumcised males, if the penis shrinks in length enough for some skin to go over rim of head, that skin will retain the easy diameter stretching ability and thus will continue to be able to cover part of head when very very soft and stay wide. This has cosmetic implications when flaccid, but also for masturbation technique during erection. A skin that has retained its easily stretched diameter is more likely to be able to be pulled over part of the glans and/or the rim during masturbation. A skin which never goes over the rim of glans when soft is more likely to "stop" at the rim and view the rim as too high a "hurdle" to jump because it is not used to have its diameter stretched that much.

It is important that one consider the forces involved when determining how much skin needs to be removed in order to acheive the desired results. The shorter the foreskin is cut, the lesser the foreskin opening force will be and proportionally greater the coronal force will be. At one point, the coronal force will be great enough to pull the remaining foreskin back down from the rim of head. with the skin staying loose/bunched up behind the rim of head unless the penis is very very soft.

This is probably what distinguishes a partial circumcision from a loose circumcision. When the foreskin is planned to cover less than half of the glans, you can expect the remaining foreskin to spend much of its time fully retracted and thus be considered more of a loose circumcision than a partial circumcision. Again, this all depends on how much your penis shrinks during its flaccid state, and if there is a significant difference in size when it is soft in your underwear versus soft when naked.