The body marks considerably more from the same impacts when under the influence of blood-thinning substances such as aspirin or alcohol. Unlike redness, which usually fades away within minutes or hours, marks can last for many days, sometimes weeks. In the course of healing, they can just fade away, discolor (bruises), pop open (blisters), and they can also itch.
In extreme cases, spanking with implements can also break the skin, resulting in an open wound that bleeds. Any injury of such extent can result in permanent marks.
Anticoagulants, when taken before corporal punishment (for example Aspirin or alcohol), lead to stronger marks. So in consensual spanking, if marks are a problem, such substances should be avoided. On the other hand, if severe-looking marks are welcome, anticoagulants can be useful.
Common types of marks
The most common type of "mark" is just the reddening of the skin with no actual damage done to any cells or vessels. For that reason, such marks are usually not considered injuries. An example of this is the handprint that comes from a spank with the open hand.
A welt is a type of lesion: a skin region that is raised in a ridge or bump, and reddened. The reddening comes from a widening of cappillaries, and the ridge comes from a build-up of extracellular fluid (lymph).
In spanking, welts are well-known as a mark caused by thin, lightweight implements such as canes, switches, birches, or whips. Cane welts have a very characteristic appearance: each stroke creates not one line, but in fact two parallel lines. These come from the skin being abruptly stretched in the moment when the cane impacts at high speed, and are sometimes referred to as "tram lines".
Welts are painful to the touch, but can also itch. They can fade after hours or take weeks to heal - this depends a lot on the individual, and of course also on how severe the welt is. Hot water, such as from a bath or shower, may cause a seemingly healed welt to reappear.
A bruise (also known as a contusion or ecchymosis) is caused by blunt impact in which the capillaries are damaged, allowing blood to seep into the surrounding tissue. Bruises are characterized by black, blue or purple color hematomas in the days following; a discoloration which does not blanch when pressed upon.
A blister is a raised skin area that contains fluid - either blood or serum (the clear liquid portion of the blood). In spanking, blisters are rare, but can appear, especially from paddles with holes that are drilled sharp-edged, rather than well-rounded off.