When you say that the fine point Sharpies are too thin, do you mean the black ones or the silver ones? The black fine point ones are pretty standard, and as you can see from roseaddams's avatar, the black fine point Sharpie signatures show up just fine. I've used medium point, but the line is too thick IMO, especially if you want to get a lot of signatures on a Playbill.
If it doesn't look like the signatures are showing up (and you're using a fine point not an ultra fine point -- the ultra fine point ones don't always work well and have exactly the problem you describe), I'm guessing you're running out of ink. The silver ones run out of ink incredibly quickly (sometimes after just a handful of signatures), and they also don't write well on a windowcard or program all the time (as opposed to a Playbill) unless they are really, really new. The black ones last a while but run out eventually.
The other thing that makes it look like the signatures are not showing up is very cold weather, but I'm guessing that's not the case at this time of the year!
"What was the name of that cheese that I like?"
"you can't run away forever...but there's nothing wrong with getting a good head start"
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