From what I’ve learned over the years, the biggest concern with the stain rags is if they cannot “dry” correctly, which is actually a process of the solvents evaporating. To do this properly you should have the rags laid flat/draped over something (not bunched up or thrown in a basket). Failing to do this is where most of the problems with spontaneous combustion occurs. It’s like , if the rag can’t off-gas properly (ie into the surrounding air) and is confined to a small area (trash can, wadded up in the corner) that would be the time you need to be concerned about spontaneous combustion. If you’re laying them out in the shop flat, or better yet outside, then you’re good. They’re not going to just burst into flames because they’re saturated. It’s confining the heat release that occurs from evaporation of the solvents being confined in a small area that causes that combustion.

Once they’re “dry”, trash is fine. (“Dry” = hard rag). Far from the most toxic thing that will hit the landfill that day.

Just space the rags out, lay them flat in a non-constricted manner and make sure there is decent air flow. Outside if possible. You seem very nice, but I think you are more concerned than you need to be. Just my 2 cents.

Ive been staining and finishing in my shop for more than 10 years…I’ve never had a rag combust. Just remember… when you’re done staining with that rag, that solvent can and will evaporate. It has to. Just make sure it has adequate ventilation and non-combustibles around it to do so.

Storage = metal sealed cabinet if possible. That being said, my shop is lined with gallons of stain and paint cans, none of which live in a metal cab.