When I use an outside mold, I place the mold on a firm surface and cover it with a plastic bag. Start at the bottom edge and start adding tufa to a height of about 2 inches. Firm it and firm it. Then move up to add another couple of inches. The tufa will slip some, if it slips a lot, it might be that it is too wet.

Cardboard would collapse without plastic. I usually use a plastic container as a mold, but I'm only doing small items. The largest I have done is about 8" X 14".

Glenda

practice on inside molds -

When you do outside molds - try making your mix more dry.
form small meatballs and apply to the sides like building blocks.

DUH. I was trying to start from the top and work down...no wonder I was having so much trouble! I'll try it again, with a small project.
Thanks for your help!

I love molds and have found the best are usually made of plastic. I usually cover them with one or more plastic bags to assure an easy release. When you're doing an outside mold on a bowl, it's important that you place mud all along the rim of the project, then plop on the center top, and work up from the rim. If the mud is too soupy, you might as well throw it back in the wheelbarrow and add some more dry ingredients. Just pat and firm the mud into place, and remember the weakest area tends to be right below the center rim. Mud has a tendency to slip downward, especially if too watery. You might want to add an extra layer of mud in this area just to make it a little stronger.

{{gwi:71004}}

This advice is spot-on---plus, if you use a plastic that extends beyond the border of the bottom (the actual rim but upside down as you work) of your pot, you can pull if up over the bottom rim and ensure that the top of the pot is contained---less likely for hypertufa to slide off.

Thanks for asking the question Linda. I haven't had alot of success with the outside mold either. I was trying a sphere and gave up as I couldn't get it to stick. I switched to portland, sand and peat to acheive that. With this info I will try the outside mild again.

I haven't been here for awhile but want to add that I use old cake pans, and bread pans and I save "Deli boxes" of different sizes to use. I grease them with plain old vaseline and they release Hypertufa easily.I think I'll try cooking oil on some and see if they release as nicely.

If you are still here, how long did it take to cure on that large bowl?

I don't care for the inner molds( mold in,'tufa out) myself... I do use plastic bowls, but on the inside (just throw the mix in z bowl and hand form the inside, trowel if you want a smoother texture). keeping the finished mix about 1/2 to 1/4 inch below the rim, makes it easier to dump the finished bowl out. when you tip it over, it has room to fall, but not too far. I like the look of the smooooth face out, opinion. square? woods the way to go, paint it first so it doesn't suck the water out.