Excess drooling is one of the problems with ball gags. Unfortunately though, there aren't many ways of getting around it!
All I can suggest is that you try your best not to panic. If you relax you'll probably find yourself more able to deal with it. It probably didn't help that it was your first time using a ball gag - you were probably a bit tense to start off with as it's something that you aren't used to.
The only other advice I can give is just to go along with it. The idea isn't always the most appealing at first, but just letting all the drool out is a fine way of dealing with it - especially if you're on your own and nobody can see you. You might even find that it adds to the sense of helplessness if you can't even control your saliva flow - who knows? xD
Unfortunately, stopping excessive drool with ball gags is incredibly difficult. You can get around it by buying smaller sizes (although obviously, they're less mouth filling and maybe not as enjoyable) I suppose. You might also find that drooling occurs less if you don't move your mouth as much - trying to talk or moving your mouth around the gag or biting down on it really increases salivation.
I know that wasn't the most helpful advice in the world but it was the best I could do
Hope things work out well for you! I'm sure you'll find a way around it so that you can really enjoy the experience!
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