hey sarah,
removing poly is my most hatred part of guitar refinishing. it's awful. but here's a few things to check out. how thick is the finish? the poly finishes that came of guitars like jackson and fender in the 1990's were extremely thick. so much in fact, i once thought the bodies were dipped in a vat instead of sprayed still I wonder about that to this day
In the case of a 90's jackson i worked on, the finish was actually thicker then the top wood on the guitar!
if your guitar's finish is this thick, i really would avoid a refinish unless it's really really really important to you.
usually modern guitars that are done in poly are done right, and the finish isn't too thick. my 1995 epip LP custom that i refinished it didn’t have a too thick poly finish either. if your guitar’s finish is somewhat thin, if it was me, I would sand it off. If your not sure the thickness, places like screw holes will give you some clues.
just be careful not to remove any binding, on some guitars this stuff can be extremely thin (i'm talking about things like the abalone multiple binding you find on guitars like a martin of taylor for example)
and be aware when you sand it, you will be making a TON of dust, and cover up anything in the room that you don't want covered in poly dust, and I would use a face mask too, just to be on the safe side. And have fun washing the poly dust out of your hair later on
it’s that bad, trust me.
you can use a heat gun too, but follow the caution danny mentioned, because he's right on with what he said. also a heat gun can put a burn in the wood if you aren't careful. one other thing that a bit annoying is removing poly with a heat gun is you really can’t use a plastic scrapper to remove the finish, cuz the plastic will just melt too, so really your only other option is using a metal scrapper. if you do use a metal scrapper, be very careful not to go into the wood itself. it's not hard to do even on a flat area, and getting the poly off the sides of a strat body is hellish. If you do go into the wood it’s not the end of the world, but now you have to sand out these area, and add some wood fill to cover up your mistake. And then prepping your body for the refinish will now take you a lot more time. When the finish is completely off the finish always try to get the body as perfect as you can with no dings or makes in it before adding a new finish. You will thank yourself later on.
if you get pass the color coat on the guitar, and if you still have the undercoat to go, you can stop from there. i've had no issues with having a poly undercoat, and a nitro top coat. it's usually not what i prefer, but it can work for ya. Sometimes it’s even better, in the case of a swamp ash body, since nitro sometimes has trouble sticking to this wood, and a poly undercoat will keep it a little more stable.
Then there are times when you might be just better off sanding the poly finish down some, and just add nitro on top of it. again, not a preferred choice, but sometimes this is your only realistic option. I did this on the headstock on my LP custom, since I didn't want the headache of redoing the headstock inlay, in case I accidentally removed it.
if you need some guidance, just gimme a call sarah. you know my number
good luck!