I think linseed oil on rags is one of the big ones that will spontaneously combust.
When I was painting cars, too much catalyst in composites can be one that gets hot enough to burn skin easily. I never had it combust but it felt close to hot enough a few times. One of my cheap and fast hacks is to use fleece fabric with fiberglass composite type resin. It soaks up a ton of resin and will take a shape in one go as something of a base molding form that can be worked with course shaping tools. That thick of material full of one mix of resin gets super smoking hot when the catalyst goes off.
I think linseed oil on rags is one of the big ones that will spontaneously combust.
When I was painting cars, too much catalyst in composites can be one that gets hot enough to burn skin easily. I never had it combust but it felt close to hot enough a few times. One of my cheap and fast hacks is to use fleece fabric with fiberglass composite type resin. It soaks up a ton of resin and will take a shape in one go as something of a base molding form that can be worked with course shaping tools. That thick of material full of one mix of resin gets super smoking hot when the catalyst goes off.