My 2 cents: I have stopped using peat moss in my projects. By definition my projects are not hypertufa and that is okay. Most of what I have read on various forums and message boards verifies my experiences with "tufa"; a very high failure rate, long unnecessary curing times, eventual collapse, and the adding of various additives necessary to strengthen the structure. Although many additives (aggregates) do little to increase the strength when peat moss ia part of the mix. My research and hands on experiences suggest peat moss is a part of the hypertufa mixes for two main reasons. Weight, peat by volume reduces project weight by at least 50% depending on the mix. And surface appearance, peat will eventually dissolve, or decompose leaving a pock-marked surface simulating volcanic rock. However, tufa is not volcanic rock. "(Tufa is the name for an unusual geological form of calcite rock. Tufa is a rough, thick, rock-like calcium carbonate deposit that forms by precipitation from bodies of water with a high dissolved calcium content. Tufa is not to be confused with tuff, which is volcanic. Tuff (from the Italian "tufo") is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Hypertufa is an anthropic rock made from various aggregates bonded together using Portland cement. Hypertufa is intended as a manufactured substitute for natural tufa, which is a slowly precipitated limestone rock; being very porous, it is favorable for plant growth. The basic recipe for hypertufa uses the classic proportions for mortar (1 part cement: 3 parts aggregate) hypertufa is composed of 3 parts Portland cement - Type I 4 parts peat 5 parts perlite or 3 parts cement: 9 parts aggregate Other recipes may call for sand or gravel as aggregates, but they add unwanted weight without necessarily adding strength. To increase structural strength and longevity, synthetic reinforcing fibers (plastics, not fiberglass) and liquid acrylic may be incorporated into the mixture. Powdered mineral colors (in small amounts) tint the hypertufa to resemble natural rock. ------ From Wikipedia, the free encyclopedia)" My mixes are variations of Portland cement, sand, perlite, and vermiculite. Sometime I use all ingredients. Usually I use sand only in projects I do not intend to carve or manipulate the shape after or during construction. The sand will eventual destroy most files and blades. Here are a few references I use: Sculpting with Cement by Lynn Olson uses cement and steel wool to create "fiber" cement and a mix of sand/cement for sculpting. Sculpture as Experience by Judith Peck covers the use of Portland cement and vermiculite (two parts vermiculite one part cement) as a sculpting medium. Sculpture in Concrete by John Mills states "the sculptor usually achieves the tensile strength so important to him, by making freestanding forms hollow, working on the principle that, by its very nature, a hollow sphere has a greater strength than a solid sphere, and a tube has a greater tensile strength than a solid rod." Creating with Concrete by Sherri Warner Hunter has 13 different mixes for cement sculpture use and three slurries to use in connecting concrete pieces.

rhonda, Sounds like you got fun times ahead experimenting. I mentioned perlite mainly because you seemed to want white and I think it's less dense and therefore lighter weight than vermiculite. However, I do like the way vermiculite affects the working texture of the mix and the gold fleck effect on the finished pieces. Perlite is a little more difficult to polish and a lot harder to carve. I use both with sand or peat (sand for solidity, peat for porosity and hopefully quicker mossy growth) in varying proportions (usually 1 part sand to 2 parts vermiculite-perlite mix). You're just not going to know ahead of time what's going to suit you best. Vibrating the drier mix does seem to have a densifying effect (even while it liquifies and looses its shape) and I think it eliminates any dry spots. There is certainly an effect - I'm just uncertain whether it's for better or worse. I think I'll try it both only in the mixing bowl & thumb-tamped into the mold and then for a longer time in the mold, just to see.

This is the deal... sand adds strength and it will last double the length of time over those made with just sphagnum peat Moss, vermiculite, or perlite, or even coir (coconut coir - the stuffing type stuff, string like, not the potting mix type). I have had sand ones last 20-30 years sitting outside. Note - I used a penetrating (not a film) sealer on mine (in any cement) to prevent freezing and thawing - you spray after final uncovering before letting them sit for 6-8 months outside. After the soaking, I will spray again, let dry a few days before putting soil in. They need to sit outside to stay damp. All of those items do well but they breakdown over time causing weakness and the more porous, the more vigorous roots can get in the crevices, push through, and cause it to eventually crumble. I have used the perlite, peat Moss, portland cement and if properly cured (cover with heavy plastic until time to unmold, then keeping for 1-2 weeks staying damp (daily misting) under plastic in the shade, then uncovering, putting in the shade and spraying 1-2x daily if the temps are above 85-90+F, just 1x day if under that, let them cure and strengthen for 6-8 months outside before doing a 3 day soak changing the water daily) before using. The soak and daily change is to get rid of the excess lime. Use a pH meter (cheap) or test strips and keep changing until the water gets down around 7-8 or let sit outside for another 4-6 months — you can decorate with them around your porch or only plant something really alkaline loving. But it’s best for long life not to plant in them for the first 6-8 months just staying damp and in the shade. Most plants like 5.5-6.5, a few like snaps, beans, asparagus, alpines, carnations, lilacs, etc like 6.5-7.5. Nothing likes over 8 and it will leach into the potting mix. Your potting mixes will be initially charged with lime to be 5.5-6.5 depending on the manufacturer but that leaches out in about 6-8+ months if outside. Concrete or cement has a pH of 12-13 and will leach into the potting mix or into the water of a bird bath. That is highly corrosive and not good for anything, and it will easily eat through paint. I like the ones with peat Moss, perlite etc, don’t get me wrong - because I can make them look older and I always use grey portland - white looks too unnatural. If I have to use white, I use grey concrete dye. If I use sand which it’s been 40 years since I made and sold them... I use also concrete dyes non toxic cause I like it to be grey and brown looking. And maybe use some of the other things like the coir to add texture and also some strength. The coir you can cut up with shears too to make smaller pieces and singe later if peeking out or just let alone. True coconut coir fiber (it’s from between the outer and inner shells.. ..it’s not coco peat) is used to make rugs/sleeping mats, mattress stuffing, ship rigging and ropes or for fishing nets. I don’t know if it would be stronger than the synthetic fibers but it would be natural. Not sure where to get small amounts but from mature coconuts it’s very strong. Read and a picture in the following https://en.m.wikipedia.org/wiki/Coir If you have done 6 months (over the winter is best - it also helps you not to get impatient and use too quickly, make in mid to late summer, go through the steps and have the uncovered time from say Sept-May. But if the pH is still high, and you don’t want to wait anymore time - use artificial plants (some are pretty believable) or plant Lily of the Valley Viper’s Bugloss Anchusa Trifolium (clovers) Polemoniums Wild marjoram Lavender California Poppies

The fact that hypertufa can wick away water, yet hold water makes this a truly great product for garden decor. My plants thrive in tufa pots. I do make alot of birdbaths and fountains and still use my classic recipe equal parts of perlite and peat moss, and 1/2 part of portland cement. Even on some of my smaller birdbaths (with walls of less than an inch), they hold water. I just get some concrete waterproof sealer at Lowe's or Home Depot. I get the stuff that's only about $8 or $9. I may apply it several times, but it eventually holds. It still keeps my projects light, yet functional. The birdbath in the photo is one of my favorites. I even broke off a piece when I unmolded it and then "tufa glued" it back on. I was careful not to handle this part when I carried it to its pedestal and I haven't moved it since. I placed a smaller tufa bowl with a plant in the center and it's a focal point for my front patio. Yes, tufa will hold water. And, for plant containers, I never drill drainage holes. I've never found it necessary.