Opening the soggy inner cores
Two days after I cast these two small troughs I opened up the molds to clean them up and texture them. First I needed to get the inner cores out. These were easy as they were (now) soggy cartons filled with sand. No worries about sticking or undercuts; I just opened the tops, scooped out the sand, and ripped out the wet remnants of the cartons.
They look pretty unimpressive right out of the molds. The sides were a little thick where the cartons bowed out in the middle so I used my masonry hammer to chip out the interior walls to match the curve of the outside walls. I also started to chip up the edges and tops to make them irregular and more natural feeling. The hypertufa is hard enough at this point that I can manhandle these pieces without worrying about breakage but soft enough that I can easily work it with hand tools.
In the photo above I've started roughing up one side of the planter on the right. I round all of the edges, use a scraper to make a random pattern of grooves, and use a wire brush to remove the top layer of cement paste, exposing the aggregate pattern below. It's pretty messy.
Top view after removing drainage plugs
The finished pieces after 1/2 hour of sweat
I say "finished" but they almost never are. I often work on them a bit more for a couple days. It's a lot like painting: walk away and come back with fresh eyes later on.
The beauty shot
I took the newborn planters outside to meet some of their kin and to pose for a family portrait, then it was back under plastic to cure.