We were discussing this old custom with a friend, and realized that we don't know much about the process. Especially the fate of the unfortunate souls - after all hot, molten tar scores the skin, and you can't really live with huge portions of your skin burned off. (Not to mention the potential for infections.)
Twain -my only source of information- make it seem like it was used for humiliation, but it looks like it was a death sentence, rather.
Anybody?

A quick Google search found this

Thanks for the answer, but I've read this link, too. It's a historical review of the "process" -and it does really address of the questions I had. Hence asking it here, maybe others know more.

Tar and feathers was never intended to be a death sentence - it was a form of punishment and embarrassment. Those who were tarred and feathered usually lived to see another day. The use of "tar" is something of a misnomer. It was not boiling hot tar that we see today being used in roofing. It was cold tar, or pitch an oily, sticky substance that was poured or slathered onto the victim and then feathers were applied. Think about how difficult and dangerous it would be to those applying the "tar" if it was boiling hot. Sometimes the tarred and feathered were "run out on a rail." This meant that they were bound hand and foot and strung up on a rail or pole that was carried by men on foot or on horseback.

The end result of being tarred and feathered was tha the victim would be covered in this mixture until he could get clean and that was a difficult process in an era of no modern degreasers. Usually the "tar" had to wear off and the clothing was ruined. Hope that helps.

From Wikipedia: "First degree burns are sustained after a split second contact with a material that is about 70 °C (160 °F). The same is also sustained after thirty seconds of contact with 55 °C (130 °F) material. The tar of that period was of such a quality that it only melted at about 60 °C (140 °F). At temperatures of 60 °C (140 °F) burns can be created with a three second contact. The thin tar layer presumably cooled quickly; nevertheless, the victims probably sustained burns in addition to their humiliation.

"Furthermore, after the tar had cooled, it and the the feathers would have to be peeled or rubbed off with lard, usually taking a good deal of skin with them. These would leave ugly scars and marks and infection could set in. Depending on how "complete" the job was done, there was also a risk of heat stroke as the tar would prevent the body's skin from breathing."

And from Historywiz

"Tarring and Feathering was a punishment that went back to the Middle Ages with Richard the Lionhearted and the Crusades. The first record is in 1189. Richard ordered that any robber voyaging with the crusaders “shall be first shaved, then boiling pitch shall be poured upon his head, and a cushion of feathers shook over it.” It was not used extensively until the American colonists revived the punishment in the 1760s. Patriots used it against British officials and loyalists in the American colonies.

"Tar could easily be found in the shipyards and everyone had feathers in their pillows. With the materials at hand, tarring and feathering was a common threat and punishment. Though the tarring was not usually fatal, it was extremely unpleasant. Applying the burning hot tar to bare skin usually caused painful blistering and efforts to remove it often made the condition worse. "