I've done multiple re-finishes on cheap and unwanted guitars just to practice my finishing and get to a point in my skills that I am comfortable selling my projects. With each project I am taking leaps and bounds towards that goal. With the several re-finishes I've done, I've tried a different method for stripping the existing finish including various chemicals, chisels, and sanding. I can't seem to find a method I really like. What is your preferred method for getting a finish off?
I hope you get some answers. Nitro is easy - paint stripper - but catalysed poly seems next to impossible. I've only done one, where I just used it as the undercoat. In fact I made some queries about this in another forum, and it appears that catalysed poly makes a very good base/filler for nitro. Collings apparently do that, maybe also Fender, but I'm not sure about that.
I use sandpaper and work by hand its tedious but less room for errors. I go 80 to cut through the poly/paint then 240/320/400/600 and there nice and smooth.
Mesa Boogie Single Rectoverb 50 series 2 combo
Randall RM100
Peavey 5150 4x12
Peavey XXX 2x12 combo
a sanding machine I'd recommend. There are a few chemical ways to go about it. But what sepeerates a good finish from a bad is how patient the person is doing it.

some insight though since you want to get really good at it. You can buy certain gauges or whatever to tell you how thick finishes are of guitars you like and it'll help determine how much finish you should use.

take your time. Let the finish cure when it needs to. Use masks and other protective gear if you are not in a well ventelated area as well. Jackson guitars custom shop has a special UV room to speed up the process of their wood finishes curing.

thin finishes = better acoustic tones - easier to chip
thick finishes = worst acoustic tones -- harder to chip
thin finishes sound way better in my opinion, you play the clean channel to a high gained setting and you appreciate the guitar more unless you're using active pickups haha.

varnish works great , tung oil , linseed oil or gunstock oil or tru oil i think they call it. They do require some maintenance to keep them at tip top shape. I've been told this is the best way to finish a guitar.

polyurethane is easy to apply and is very durable. The repercussion is that if you dent a guitar severely you'd have to level the finish or re-finish the entire guitar and that is a longggg process. It's bad for the lungs and causes brain damage as it's lead based.

nitrocellulose lacquer - this is harder to work with, a better acoustic tone or so fender says. It's terrible for the lungs and causes brain damage as well as we know ...but it's super easy to do drop fills to get rid of dings in the finish. Plus lacquer I think big guitar building companies aren't allowed to use it any more because it's bad for the planet. But to re-fill places with lacquer that have been damaged clear nail polish to krazy glue and sand/polish to whatever grit your finish needs, say 2000 for gloss then buff with compounds.
^^^ Good post, IMO.

Just a couple of comments:

I use a cheap orbital finishing sander, and it works OK if you want to completely strip the finish, but, as you say it takes a lot of patience.

I've use oil finishes. I like linseed + a generous amount of Terebine, my music store mate prefers Birchwood Casey Tru Oil. The big advantage of these is that they are very easy to repair, the downside is that they offer no protection from dings. I've heard suggestions that these finishes aren't good for necks because of stability issues, but my old bare-neck Gibson is very stable. I would chance it and make changes if necessary. - not difficult on a neck.

Nail varnish is good for nitro, but superglue will leave a witness line. Superglue is good for catalysed poly, and I've done some completely invisible ding repairs with it.
Much thanks for the posts.

Here's some more about my experience with this: As far as the ones I've tried, sanding has been the biggest pain, but at the same time it has given me the best results. I have a good respirator that I've been using and a well-ventilated shop, so chemicals haven't been an issue as of yet. My favorite project was a combination of chemicals, chisels, and sanding. I used a thinner to break down the finish before using a chisel to get some of it off and then sanded to a nice a smooth point. I was just inquiring on here to see if there is a sure-fire method for stripping. As with most things, it seems there isn't.
The circular style sand paper on a matching pad, have you tried stripping down until you can taper a piece of artwork onto the freshly stripped wood?

It is what was given to me to sand an antique car. Rust removal and also all the steps in priming.
Besides that I do not know of a top recommended slow process way of removing guitar lacquer other than wear from sweeping it up and down.