Any material of an organic nature like peat moss, bark, sawdust or cat food will rot out eventually, leaving "wormholes" that water can move through and, if not kept dry in winter, can freeze, expand, and break the object. I was just reading a book on tufa troughs, and the author said hypertufa (cement/peat/perlite) can last a bit more than 10 yrs, but will eventually fall apart. Concrete that the Romans built, on the other hand, is still standing.

If you want your wall to exist longer than 10 yrs or so, you might want to consider lightweight concrete. This resembles tufa without the organics. The usual (roughly) basic mix is 1 part cement + 1 part sand + 1 or 2 parts perlite. There are other things you can include, such as vermiculite, but there is the asbestos issue with that, if you use much of it. (Vermiculite & asbestos are mined together, it can't be separated.)

Some of the people here use latex paint in the mix (or surface mix, anyway), or painted right onto the cured surface. Indoor paint is more sensitive to UV fading than the outdoor kind, and either one may only have a minimal color effect when mixed into the concrete, due to the dilution and the gray color of the concrete. Even with white concrete, it will probably be pale. I pretty sure the 10% rule would apply with this.

But there is certainly no harm in experimenting. If it doesn't have the effect you wanted, you can decide if you can live with it, or never use it again. I would suggest small samples for testing, no something the size of an elephant.

Sue

In a little over ten years all the beautiful pieces that are being displayed on this forum will all fall apart! I was hoping to get a little more miles out of my pieces. Terribly sad!

Serene

Serene you can always put a strong mix down first and then top coat with a peat recipe for the look.
I do a lot of stuff this way now.
It allows me to go nuts with peat on the surface for a great look but still have a strong pot.
If your topcoat degrades you can always go over it with another topcoat later.:)

Hey, everything degrades. We only need look in the mirror to remind us of that. (Sux don't it?) At any rate, I have several pieces that have been outside for 5 years thru upstate NY winters & they show zero signs of degradation. I find that 10 year statement a little hard to swallow. Think about it... The sand/concrete mix is going to last one heck of a long time. How many 30 year old patio slabs have you seen at friends houses? The only difference between those and tufa is the stone vs. peatmoss. A sufficient percentage of that peat is practically dust or particles/strands so small that their eventual disappearance shouldn't make a difference. Larger pieces, though they may eventually disappear, are not so prevalent in the object as to sufficiently weaken it (as long as you're not building bridges or anything). I would think that it would only add character to the piece. This is only my opinion. I'm not speaking from expertice on the matter, but it makes sense to me.

Only time will tell.

I'd feel better about the longevity of Hypertufa if I could find a piece that has been outside for five years, even 3 years.
I have spent several months searching in my area, asking everyone I know and I have found people who have made tufa in the past but I can't find a single example of tufa that has stood the test of time in my area.:(
Zones 3 to 5.