Correct me if I’m wrong but does the Dynamite startup process basically open the maxstart or vizstart file, starts the material library as empty then populates it with the dynamite surfaces and sky materials?  i.e. it ignores any materials already in the startup file?

DVSP doesn’t use material libraries as such. However, if a multi/sub-object material definition called DynamiteSurfaces does not exist in the nominated vizstart/maxstart startup scene, it will be created automatically during startup.

However, if you wish to store a custom DynamiteSurfaces material in your own custom startup file, it must be applied to at least one object in the scene to prevent DVSP automatically overwriting it when starting up. For this reason, I would suggest saving a sphere (or any 3d object) in your custom startup scene, and apply your custom DynamiteSurfaces material definition to it before saving the file.

When you start a new scene, you’ll see the sphere which you can simply delete and then continue working - this will allow you to use your own material definition instead of ours.

Yeah, this is what I noticed and figured as a work around, thanks.