My wife picked up an old cedar chest that needs refinishing. It's nice, solid cedar, so I said I'd do it if she helped me with the sanding.

Busted out the ROS with 120 grit and immediately started clogging the paper bad, small spots of finish turned into coin sized accretions within seconds. I jumped down to 80 grit, same problem.
I took some denatured alcohol to it, which definitely affected the finish. With some minutes soak and a few minutes scrubbing it got gummy and sticky, and stained the rag. After drying, I can see that alcohol liquefied the finish, as there is now a glossier area with drips around the area I rubbed, indicating I pushed the solids out to the edges with the rubbing. The middle of the rubbed area still has finish, but much less. Test sanding indicates I could probably sand without ruining paper now. The alcohol was very slow and took a lot of rubbing though, hopefully there is something better suited to the job.

I assume I'll need to use some sort of chemical stripper before I sand to remove the bulk of the finish, but I've never done that before. Should I buy a purpose-made product, or just use something like mineral spirits/paint thinner? Hopefully someone can give me some advice on how best to proceed.

A couple of photos of the area I rubbed, the top which looks sun/water damaged, and a closeup of the way the finish cracked up in the damaged areas.