Walter,
After looking and the sample photos, looks llike the aggregate % per size looks like 40% large ,20% medium and 40% small. It makes sense to me.

One thing i am curious about though, is the hardness of the cured epoxy of these samples. I know you to not have the equipment to do Shore D testing, However if you have and automatic centerpunch you can easily compare epoxy hardness by punching one of your samples and one of the sample you got from overseas. The sample that the dent is smallest is the one that has the hardest epoxy.

I have a hunch you will find out that the sample from France has a harder epoxy than the resin you are using.

I believe that using a resin that has a cured shore D hardness of 85 for instance with not additives will out perform any resin with a 65 with additives.

it is a known fact that Hardness of steel has a direct relatioship with it's tensile strength, I am sure it is the same for epoxy resins, this is a gut feeling as i have not put my hands on any studies that proves it for epoxy resins or plastics in general.

Just to give you an idea;a Shore d hardness of 65 is a bit softer than Polypropylene and a shore d hardness of 85 if stiffer than nylon and has a similar hardness to brass and aluminium.

Larry, Cameron I need your 2 cents on this.

Thansk, best regards

Bruno