Quicksand Fans

Hey all. I've finally got the resources to build my own pit. I wanted to ask some clarifying questions to get some feedback before I inevitably step on a rake and wack myself in the face.

Due to the limitations of my rental property, I'll be doing an above ground pit. I'm strongly considering buying a 55 gallon steel barrel with a removable lid. The dimensions of the barrel are 24"x24"x35" tall. I think either myself or my wife could stand in something this size and crouch to simulate a further depth. The barrel would sit below a raised platform, you'd lower yourself into it from above. Per an earlier forum post from Fred, it seems a 50lb bag of bentonite gets you ~1cubic foot of clay. The barrel can hold 9.4 cubic feet, but displacement from a person would knock off about 1.5 cubic feet from that number. Just to be on the safe side, I'm thinking that'd be 10 bags of clay.

I'll also be snaking a hose from the top to the bottom of the barrel. It'll be a closed loop heating system, that being said, we live in Arizona so it probably won't need much heating. I'm also adding a catching plate to both the bottom and top of the barrel to mitigate spillage.

I'm aiming for maximum sinking, minimum wam. I'm going to buy a few samples of bentonite and kaolin and some concrete dye and test to see which one is best. I'd read a study somewhere that salt + bentonite is extra jiggly, so I'll see if that makes any difference too. My wife is making spreadsheets lol.

I'd strongly considered building and framing almost a permanent concrete form out of 2x6s and plywood. I'd make a sort of boxed in stair case, then reinforce the exterior with some 2x4's. In the sample I built, I'd have about 14 cubic feet of clay. I'm terrified of it failing, considering I'm estimating it to hold about 1500lbs of liquid clay. It's going in the garage on a concrete deck, so I'm not worried about foundation problems or anything.

The questions I have: what is the weight of a cubic foot of water logged bentonite? Is it more or less than the equivalent size in water? I've been going off an assumption that it's double the weight of water.
Will I need a respirator when I mix the powdered bentonite?
Am I undershooting by using a barrel? Is it far too small? Should I just go with the "staircase box"?

Thanks guys. I've cycled through damn near every home build post on this forum, so I hope I'm not asking repeat questions.

I never built a pit or did I. I would not use a metal drum. They make many sizes of plastic drums - but you would have to find a place that sells them. The come in many sizes - round and square. I used a large green round landscaper collection bin - you can buy that at most Home Depot stores. https://www.homedepot.com/p/Chem-Tainer-Industries-60-gal-Green-Round-Carry-Barrel-Trash-Can-CBR60/100119163

I used a mix of peat and top soil when I made mine. - Question is how to keep it soft? I had to take half of it out then add water to what was left and mix it then kept adding more water and the stuff I took out. Could never come up with a way to keep it soft.

Not sure I have all the answers but I have some. The specific gravity will be roughly 1.3 (that much times the weight of water) although it will depend some on how thick you mix it.
Keep in mind that bentonite will be very slippery so be careful about your footing. You might want a step or two on the inside so you can use your legs for getting out. Remember that the surface will rise quite a bit when you get in. Your external sairs might be dangerously slippery. A respirator would be a good idea when handling dry bentonite indoors. Unless you intend to do photography I would omit the dye - just turn the lights way down.

Another thing to keep in mind is that it is best to add dry bentonite to water first, to initially make a thin mixture, and then mixing in more and more bentonite to thicken it, and then mix in more water and bentonite as needed for the desired volume, because if you first add water to dry bentonite, you could wind up with a solid mass of bentonite that is hard to mix.

Thanks for all the feedback! I've decided against the barrel since it'd be a little too cramped for two. Adding some safety rails so we don't throw our backs out exiting too. I'll post pictures in this thread once I start building!

Be sure to sample both kaolin and bentonite on your skin before purchasing in quantity. Bentonite is watery whereas kaolin is sticky and stays on better to make a heavy mud felling possible.

I found in the one ton mudbath I had in my house that at the thickness I used, the mud was about twice as heavy as water. Definitely wear a mask or respirator, clay dust is very hazardous.

In my limited experience with a in-ground pit I made (I may post more on that experience in the coming weeks), which is probably about the same size, or just barely bigger than a 55 gallon drum, that's probably not big enough to submerge in, unless of course you qualify for that TLC show Little People, Big World. The deepest I could get fighting buoyancy was about the tops of my shoulders, and I thought if it was maybe a foot deeper, and I had a little more elbow room, I probably could've submerged, or at least came very close.

Just a spitball of a thought, but as kid, we had one of those hard plastic above ground pools that was about 4' deep and 18' in diameter, and could be (somewhat) easily disassembled and rolled up. Not saying you need 18', but you could cut the side and coil it around itself until you get down to maybe, 4' in diameter. That way the walls would be three or four times the thickness. Just need to figure a way to keep it from uncoiling, maybe securing it with screws into a 2x4 (just so the screws aren't sticking out to cut you), or you might be able to wind cargo webbing/straps around it, those should be able to hold thousands of pounds. Another consideration is, how to get in, and practically out of it. Even with the 55 gallon drum, if there's nothing to stand on around it, it might be kinda challenging to get out of, so a small deck or platform of some sort may be in order.

But yeah, if you just want to have some messy fun on a budget, the 55 gallon drum would suffice. However, if you really want to go deep and have the means for it, bigger is always better