Aloha all: How long does it take for celluclay to cure? I did a base of celluclay over a plastic bottom of a clear display case and it has lifted off at the edges and produced a crack. I put it down about a week ago. I don't want to fix it then have it lift and crack more. Thanks in advance and sorry no pics, but I'm away from my computer.

Happy Modeling, -zon

It depends on how you mixed your celluclay and how much water you added. It could take up to a week to harden. If you leave it outside in a sheltered place, the moisture would evaporate much quicker than in a basement, for instance. I've found that celluclay will more readily lift off a plastic base than a wooden one because it won't adhere well to plastic. If it lifts off a bit just fill the gap with more celluclay. I've mixed in powdered paste (the kind for making papier mache) available from arts and crafts stores. You could also use white glue, but the dry paste is cheaper.

It depends on the weather conditions you live in. Using plastic may not be a good idea as there is nothing for the clay to adhere to. Wood is best but make sure to seal the wood, don't use a piece that is too thin as it will warp and score the surface to give the cell u clay a footing. And make sure you use a goodly amount of Elmer's white glue to help it all bond. A dash of liquid hand soap is recommended in the general mix. The amount of water used in the mix is also important. Plenty of web sites with tips on this very topic.
Ironmike

As an addendum to this good advice, one additional technique I have seen used in a number of step-by-step accounts is to put a number of screws into the base, screwing them in just far enough for them to hold securely, leaving the shaft and head standing up from the base like a mushroom, with the ground material is packed in tight around the screws so that they act as anchors to hold the ground material and keep it from warping and lifting.

On a plastic base, that would be problematic for screws, given the thinness of the plastic, but if the base isn't flush on the underside small bolts could be used to the same purpose, with the nut on the underside epoxied to the underside of the base.

Thanks for the replies and the suggestions guys. I agree that celluclay over a plastic base is probably not the best choice, but I'd never done it before and now I know better!

I just re-checked my old photos and it's been more than a week since I first set down the celluclay, so I will take a chance to repair the crack and fill in the lited edges this week. The photos will be in the Railroad Campaign thread.

Sean: I really like your suggestion about the bolts and could have easily built some "mushrooms" out of stock styrene if I'd known sooner. Maybe in the future.

Again, thank you much!!

Happy Modeling, -zon