The mouth, like the nose, must be seen as a shape and not as a contour. Drawing the mouth involves all the elements of shading: cast shadow, halftone, shadow edge, reflected light, and full light.
Here are some items to pay attention to when drawing a mouth:
A corner of the mouth Portrait zeichnen lassen is called a pit. It is the darkest area of the mouth and is made the darkest dark, i.e., the darkest value on your five-value scale. This is important. It gives the mouth a sassy look.
The shadows below the mouth are fairly light. They are best done in halftone. This is because the area under the lip is still at a fairly steep angle in relation to the light source.
There usually is a highlight or full light on the lower lip and should not be overlooked. The location of this highlight is of particular importance.
* Reflected Light
A less obvious but nevertheless important element is the reflected light that is usually found on the upper lip just above the line that separates the two lips. Make sure to pay attention to this reflected light.
* Darks and Lights
The upper lip is always darker than the lower lip. This is because the upper lip is angled away from the light source while the lower lip is angled towards the light source. That’s also why the highlight can usually be found on the lower lip. It is also the reason why you see reflected light on the bottom of the upper lip.
* Lip Line
An accurate rendition of the line separating the two lips when the mouth is closed is of the utmost importance to achieve a good likeness. As always, let the values determine the line. Do not draw actual outlines because that leads to an artificial flat look.
Each tooth must be drawn accurately. This is important because it really changes the look of your subject if a tooth does not have the correct shape. Just think of how your looks change when you have a missing tooth.
Draw teeth by drawing the gum line (this is an example of using the idea of negative space drawing). Also, teeth are seldom white. In fact, because of the cast shadows as well as the natural color of the teeth, the values are often much darker than you would expect. Check your photograph carefully for values.
The vertical lines that separate the teeth are very subtle and soft. Make sure you smooth these lines out and reduce some of them to just a hint. And do not forget to render the shadows that fall on the teeth.
* Open Mouth
When the mouth is open, you will of course see teeth and also the inside of the lips. It is very important to note the changing values on the insides of the lips. Rendering these changes in values allows you to give the illusion of the roundedness to the lips which otherwise would show as flat or planar.
Finally, note that the mouth is critical to the likeness Portrait zeichnen lassen of your subject, particularly if it involves a hint of a smile. Be accurate with the mouth line, the width of the mouth, the shape of the teeth, and the outline of the lips. When your drawing is finished and you feel like something is not quite right, the mouth is one of the places to check for inaccuracies.