I ran out of cell o fill and had to run out to West Marine to grab some sillica. Turns out the same amount (by volume) of sillica is worth about half as much cell o fill. Now, I'm waiting on my newly ordered cell o fill from CLC instead of working on my boat since I'm out of the new stuff and truthfully, I didn't like working with it nearly enough. It was WAY lighter and got in the air and if you consider how much you need to thicken with it, WAY more expensive.