[gt40]

Update:

I came home and the slab was baked by a full day in the sun and solid, so I took a peek by removing a corner. Good news it is really tough- inadvertently smacked it a few times with sledge hammer removing the mold material and it didn't even dent, let alone crack. The 4lb sledge fairly bounced off of it. The part I removed looks good - feels and acts like a solid rock. I took a grinder to it and it grinds like a rock too- you can see that part on the upper right part of the pic.

The bad news is I didn't use enough wax or a proper mold release. Fortunately I taped the entire saddle section and all corners which are radiused and those areas are coming off easy- the flat side- not so much. I spent an hour with a chisel and crow bar with the sledge to remove the end and a little part of the long side. Any secrets to making this easier?