Could you wrap the outside of the basket with duct tape to keep the hypertufa from oozing out the holes? The basket might not be rigid enough to hold the mix...I don't know but would love to see the results if it works!

It's possible that the alkalai in the cement will destroy the plastic in the laundry basket, weakening the whole thing.

It might be better to use the laundry basket as a base for a couple of layers of small-hole chicken wire (remove the plastic basket before applying the cement (or put a garbage bag over the plastic, apply the outside layer of hypertufa, then remove the laundry basket-garbage bag).

Chicken-wire works with the cement to make the whole thing stronger so you can go thinner and lighter.

Please correct me if I am wrong, but this was my train of thought:

When I made my first 15 gallon pot using a plastic pot as a mold, I was told that for this size, no reinforcement is necessary. This pot will be smaller (16" diameter, 12" tall), so I thought I could get away with just covering the plastic with tuffa mix. Even if the plastic is eventually destroyed, by then I figured the cement will have cured. In my line of thinking, the purpose of the basket was purely to give me something to stick the mix to and guide my form, not to add long-term structural support to the final product.

If this will work, how thick would the tuffa need to be, and what recipe would be best to use?

Or would the amount of dissolved/destroyed plastic inside the resulting pot react chemically some way with the cement to weaken it or create a void or?
thanks!

It would probably work for a while, but I wouldn't plant trees in it.

The trees could live a long time.

Tufa isn't known for its strength, nor a long life.

The tree grows, the roots expand, the organic materials in the tufa decompose, the holes fill with water, and then winter comes.

It would probably work better with concrete, rather than tufa.

Hmmmm...that makes sense (unfortunately since I am all set to go with tufa). So that brings up new questions:

What recipe for concrete would allow you to apply and shape it like hypertufa? How thick would it need to be? And could you then coat the inside and outside with a thin layer of tufa for aesthetics?

Thanks Belgianpup, that is disappointing but better to learn this now I guess!

I'm one of those tufa artists who like to keep everything really simple, so depending on whether you're doing an inside or outside mold, I would line (or cover)the basket with four or five large garbage bags. I've done many baskets, and I just heap on the plastic bags.

As for longevity, I've had many planters for over five years and they get almost like rock with age. So, I've not experienced them falling apart. But, the recipe I use is always equal parts of portland cement, perlite and peat moss. Good luck!

Thanks valoson,
That is encouraging!
Wouldn't it be the most simple to just cover the basket inside and out without having to remove it at all? Do you use reinforcing fibers to? If so, where do you find them? How thick are your planters that have lasted 5 years?
Thanks!

You can try covering the basket but I think it would be more work than if you just used it as a mold with several big garbage bags either lining it or covering it. I've made some huge bowls and planters and most of them aren't much more than two inches thick. In fact, they're usually a little thinner at the center rim because the mud tends to settle to the bottom. If I'm using the basket as an outside mold (a term I use for molding along the outside and thus making a bigger project)is to place my mud evenly along the bottom edge and gradually build up. I then place the mud on the top center and gradually build down, eventually filling the holes. On a big project, the weakest part tends to be the high center because the mud slurps downward. Sometimes, instead of fighting it, I'll just let it dry for a day. I then place another coating of mud to the center and center rim area. This just reinforces the weak area. If the bottom dried section is ready for wirebrushing, I just go ahead and do it, and then hit the newer section with the wirebrush on the next day.

Most of my projects have two inch or less walls. They tend to be thicker at the ledge area. It will be an easier process if you use an inside mold, using the laundry basket to mold against. Just plop mud in the bottom and gradually build up the sides. You're project will be the same size as the laundry basket. Just make sure to use three or four plastic bags so you can just turn it over and release. Hit it with the wirebrush and carve along the edge with a putty knife to even it up.

As for drainholes, I never put them in. I've found that plants do nicely in hypertufa because it naturally wicks the water away. In fact, I find that many plants thrive in hypertufa for years.

Thanks valolson,
what mix do you use that allows it to wick away water without drain holes? I had thought that would happen but many have told me otherwise. My first hypertuffa project was a large planter and the pvc pipe I put in for holes backed out a bit without my noticing so the holes just closed up. When I was "curing" it, the water seemed to stay in without draining. My second project was a bird bath and I was worried it might not hold water but it seems to. Does the 'tuffa get more "wicky" with age as the peat disintegrates or are you using a different formula?
Also, do you use reinforcing fibers? I finally found a place to get them ($10.00/lb bag), if so, how much do you use?

I am not eager to use plastic over my mold because I used thick plastic over my mold for the bird bath and I am not happy with the plastic lines/pattern that resulted on the bottom of the bowl, does this problem go away when using several thinner plastic bags instead of the thick plastic?

Thanks!

About the drainholes. I just know what works for me. I used to put in drainholes when I first started doing hypertufa, but I forgot to put in drainholes in some of my planters. Well, I discovered that many of my plants did just as well, or even better, in those projects with no drainholes. When I make birdbaths, the water will stay in for a little while, but you usually have to add a waterproof sealer several times to really get them to hold water. I just use Thompson's. So, hypertufa doesn't usually hold water just on its own.

Also, you can use the thinner (cheapie) type black garbage bags. Yes, they can leave lines, but when wirebrushing, most of the lines can be removed. But, I'm one of those that likes an occasional wrinkle or two, except on my face.

Thanks, I still want to know what recipe you use that allows wicking so well that drain-holes are unnecessary.

I really want my pots to breathe/wick but my recipe (1:1:1:1 - portland:sand:pine dust:perlite) doesn't allow that (so far). I filled my pot up to soak for a month before putting my tree in it, and it stayed full of water. Someone I really respect on the container forum said he has had pots for 10 years but they don't wick at all, so I am thinking it must be a difference in the recipes used. He used something like 3:3:2:1 - portland:peat:perlite:turface.

Maybe I'll try one with the thin trash bags and see how I like it. After wire brushing, if I didn't like it, could I still smear a thin layer of tufa to cover it?

Thanks for your help!

All I use is one part portland, one part perlite and one part peat moss. For a planter, you can even use one less part portland. I've done that many a time, and it lightens them up and they can drain even better. But, for the most part, I use equal parts. I used to use fiberglass shreds for bigger projects but I really couldn't tell the difference in strength...but that's just my experience.

I like to keep things simple and agree that making it on the inside of the basket is the easiest. If you line the basket with plastic bags, you are still going to get a nice weave pattern on the outside from the plastic of the basket. Can't tell by the photo how flexible that plastic is, so it may bulge on you while you are working: I would use whatever mix works for you; I use 1 to 1.5 to 1.5. Make sure the walls are at least 2" and if the mixture isn't too wet you shouldn't have any problems with "slump". If you live in a zone where you get a lot of freezing, pack the mixture tightly to get rid of any air pockets; you don't want water getting in, freezing and breaking the walls. If you compress your walls tightly, your finished pot will not wick a lot of water, so make a few drain holes in the bottom to make sure you don't get a boggy mess in the bottom and kill the roots of your plant.

thanks a lot for all of the tips!

Hi granburyflowergirl~
I know this is an old thread, and I hope your still looking in on this forum. :-)

I was wondering if you ever tried this, and if it worked? I'm looking for ways to make large pots for tree's.

I was also wondering if you ever tried using turface fines. I know there's a thread where you had asked Al about it.

My son and I made our first attempt at hypertufa today. Just little pots and i'm anxious to see how they turn out.

JoJo

Hi JoJo! Yes, in my opinion it worked great!!!! I just used a bit of drywall mesh tape around the holes and applied tufa to the outside and then the inside. I have used the turface fine as well as the pine bark dust with great success. I am really happy with how these turned out, they are a bit heavy due to the size but that is a good thing here because of the strong winds that would otherwise knock my plants over. Here are some pics:
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Sorry if some of the pics are sideways, I rotated them in Photobucket so I don't know what the deal is
Nik