Of course teething is part of it and he can't express himself very well so some babies use biting as a way of expressing their frustration.
But DO NOT tap him in the mouth, please. He is barely a year old. He is too young to really understand time out but I do think it's not a bad thing to use at this age just don't expect him to "get it" for some time. And you only place them there for one minute per year of age.
The best strategy is to try to catch him right before he does it and give him a stern "no" and follow with "no biting". Or same stern voice during/after he does it. That is one reason that I only ever use the word "no" for something serious. That way it holds more meaning than if they hear it on a regular basis.
Sorry Julie, but this kid is 14 months old! Yes, human bites aren't fun but he is 14 months old! This is part of parenting. When you know your child has something going on-hitting, pinching, biting you have to be vigilant and consistent for them to learn. But he is 14 months old! You don't tap them in the mouth and you have to just keep at the time outs before they will get it and it ain't at 14 months old!
If he is teething he's in pain. Not like he can say to her "Mother, I have a terrible ache in my jaw. Could I possibly have some tylenol?" If mom thinks he is teething then trying some tylenol preventatively would certainly be in order and may help the situation tremendously.
And she never said he was biting out of anger. I brought that up because it is very common with a baby that can not express themselves and most 14 month olds can't do that very well verbally so it's usually a physical response of some sort. Just throwing it out there for mom so that she can explore all avenues and know appropriate ways to watch for it and deal with it.
My advice was to modify what she was already doing and to be consistent because at 14 months old they are very, very young and have to see and hear things over and over to get it.