Branding is most typically associated with hot branding whereby a very hot piece of metal is pressed against the flesh to cause a burn and subsequent scarring. The scar prodcued will take the form of the brand and will be permanent (laser removal may be possible in some cases). Freeze branding is another option, but this type of branding relies on alteration of pigment producing hair cells and may not produce the desired result when used on humans (on body areas with areas of relatively low hair density).
Branding is most commonly used on livestock to identify the owner of the animal and/or the breed. In ponyplay, branding serves a similar purpose. A brand in ponyplay can serve as a mark of ownership. It can also serve as a mark of status since certain brand designs/symbols might only be applied to animals of a particular breed and even then, perhaps only to animals representing the best of that breed.
Similar to other forms of body modification, branding is a form of body art and is not limited to either ponyplay or BDSM. While branding as a form of body art is not uncommon, care should be taken if you decide to perform any type of branding on yourself or your pony. Burns can easily become infected and applying a brand for too long can cause serious tissue damage.
Hot branding is performed in one of two major ways:
Strike Branding - This type of hot branding is performed by striking a hot piece of metal (pre-heated over a flame) against the skin. For livestock, identical application of a brand to multiple animals is often a requirement so a branding iron which contains a complete design is most often used. This method allows the entirety of the design to be transferred in a single strike. In BDSM and body art, where the brand design will usually be unique to each person, multiple strikes with a thin piece of metal are often used. This allows the piece of heated metal to act like a pen.
The advantages of strike branding in ponyplay are its low cost and authenticity (in regards to similarity to livestock branding). The image at the right illustrates two strike branding tools. On the left is a thin piece of metal used commonly in human branding to create unique designs. On the right is a livestock brand where the branding iron contains the entirety of the design to facilitate single strike branding.
Electrocautery - This form of hot branding makes use of a thin metal probe that is heated by an electric current. The major advantages of this method is that the current can be precisely controlled without having to remove the tip of cautery pen from the flesh. The greater control of the heating with this method permits very intricate designs that would be difficult or impossible to achieve with strike branding.
Eletrocautery systems designed for medical use, including battery powered electrocautery pens, are available, but these should be used with extreme caution. The photo below shows an electrocautery pen being used to for branding body art.
Temporary Branding - This is not really a separate category since either strike or electrocautery based branding can be used. However, with temporary branding the goal is to use either a lower temperature of the branding iron (via controlling the current on an electrocautery device) and/or a shorter application period of the iron to the skin to prevent permanent scar formation.
Temporary branding can be a great part of ponyplay since it can be done over and over again without covering your pony in scars. I think this is an especially appealing idea if you or your pony has been branded once with a permanent brand and loved the experience but don't want to have a bunch of permanent marks.
That being said, I personally like the idea of creating a nice design then getting it branded permanently on my skin. Aside from the connotations of ownership, brands, like tatoos, are just cool.
To incorporate strike branding into ponyplay, decide whether you wish to use a single strike type branding iron or using a thin piece of metal for multiple strike branding. While the former appeals to me most, the reality of using the single strike method requires design and production of a custom branding iron, which may not be feasible for most people involved in ponyplay. Moreover, the second method requires multiple applications of the extremely hot metal iron, which to some of us (read: me) has a certain appeal. However, the multiple strike method requires a steady hand and a pretty good eye to make sure overall design will come out as you hope.