Thanks HJ, and thanks Bud at Suncoast Plumbing for responding to my earlier question about repairing a cracked toilet tank. However, Im still not convinced. New Info: I cracked the tank myself last fall by tighening one of the bolts too much. There are just 2 cracks radiating from the bolt hole – one is 2 inches long , the other about 3 inches. Both are hairline cracks heading to the side of the tank, and they re not getting bigger. It appears that they are so small that rust particles cant get through and are being caught in the crack. I plan to brush the tank surface real good and clean it with a solvent, and then lay down a thick bead of silcone caulk on the inside of the tank. Whadaya think? Related question: Why, since the cracks were caused last fall, did they take till now to start leaking?