I just made my first batch of this stuff last night and I was wondering if anyone knows any tricks for the curing process? I am thinking I will just put it in a tub in the backyard and try to change the water every few days. I hear some thing about adding vinegar, but I have no idea what this will do. Is everyone's agrocrete so brittle? I guess I thought it would be a little stronger than it is. I used agro and type one portland, with some crushed coral mixed in that I used for the molds. Any advice would be great. Thanks.