clay use for slabs

Off today to our regional pottery supply store to lern what type of clay would need to be used to create the dike to retain the soil.
This will be my first attempt to redo a maple forest and i'd like to have the right stuff. Do i need to add anything to the clay mix?
Drainage? Could use some advice from those that have done this before.

Is this the same as "muck" used on rock planting? If it is, then there are numerous recipe out there with different clay recommendations. It seems regular clay or even potting clay is used. Sphagnum moss, clay, and water are the main ingredients I've always seen. I've read that simpler is better too.

Check this thread https://ibonsaiclub.forumotion.com/t7645-recipe-for-muck?highlight=muck

Good luck!

What our members use (I haven't done it myself) is bentonite (sp) (plumbers mud) and long fiber sphagnum moss, wear gloves.

appreciate you both for the input. spagnum i have lots of and will see if they have bentonite clay. I know from fish farming it is used in a mix to hold a pond together to retain water. apprciate this chatline as a resource. Now i know what to ask for. Could use info
to see if drainage holes need to be made or will it seep out underneath?

I've read that they are not necessary. Slab planting are shallow to begin with and any little excess water should find its way out through the sphagnum. If you are worried, then just put pure sphagnum where you want it to drain. Just my thoughts and not from experience.

I mix shredded spagnum moss with adobe clay soil ( which is what a lot of the soil here is) grind and mix them together then add water to the desired consistency. I never bother with drainage holes in the clay drainage has never been an issue for me with a slab. I'd be interested in a commerical clay that can do the same thing

Hi Dick/Bob,
Just speaking from the top of my head here (I know.... it can be dangerous on the forums )
The difference in the amount of rain from your location Rob in California is a lot less than Dick would get up here in the pacitic northwest. If the slab is really flat I'd put in some form of drainage.
Looking forward to seeing the end product Dick.
Cheers Graham