Jacki, regarding use of slag, I guess it depends on 1) how fine it is (if it's too fine it wouldn't work as well) and 2) what the slag is made of and if it's mixed with anything else - just make sure it isn't a metal that reacts with cement (see below).

Lynn Olson, longtime concrete artist, says in his book, Sculpting with Cement, that steel (esp galvanized) is extremely stable in concrete as long as it is in complete contact with it, but steel that is coated with another metal can corrode. Copper, bronze & brass may retard setting where they contact the concrete, but they are stable in it. Nickel, chromium, silver & tin resist corrosion. But aluminum corrodes in cement.

Pinch pots would be adorable with your seedlings!

Good to know about the metal - they're sandblasting metal, and most of it is steel, so there will probably be some very fine pieces in it (dust like particles). The slag itself is made from iron ore, a by product of the ore refining process. I'm thinking it must be similar to sand, but made from something other than silica. Hmm. Testing. The particles won't be very small, and I will probably sift it to get really fine particles out. Apparently, you can no longer use silica for sandblasting, so he's now doing researching the life expectancy of a sandblaster who uses black abrasive slag instead. Only half kidding...

Testing?

Yes, testing, if you can use slag for hypertufa instead of sand. I think we should continually push the envelope and use waste material to make whatever crafts possible. Just my opinion, of course, but just think of the wonderful succulent containers we could make...

Okay, as today is the first nice day, and tomorrow the same, I'm hoping that this works really well and we don't get below freezing any more!. I'm not really ambitious today due to lack of energy (that darned MS, you know?) so here's my system: sifted peat moss (this is damp, as it comes right from the bale): perlite: slag: Portland cement powder, mixed and then water added. One part of each of the above. I'm just making pinch pots for now, due the above reason.

Back with an update...

How long do we have to wait to see them ready to go Jacki. How exciting.

Can't wait - have fun!!

It was fun - so much so, that I went back and made a second batch for a birdbath, with enough for another little sag pot. Those were made using an empty vegetable garden bed, and the others were pinch pots made in ziploc bags.



They turned out so cute! Here they are soaking for as long as I can stand it before planting them.

Awesome Jacki. How long do you leave them in water?

Why do you soak them?

I'm just following the directions from somewhere here on the forum. Now, of course, I can't find it.

Here it is:

The thread "Little pots" in Hypertufa, the Look of Carved Stone

Aha, so soaking in water leaches the lime out of the mixture. : ) Thank you for the link Jacki.

Cement needs moisture to cure properly. It takes 28 days for cement to reach it's best strength for use. And like Lynn said, it leaches out the lime. Some people skip the 28 day cure but I've always done it because in my freeze/thaw climate I want them to be as strong as possible.

Curing should also be done at a minimum of 50 deg. F.

Thanks for the clarification, Chris. I'll try to be patient...

I would think the waiting to be the most difficult part.

It definitely is! But pays off in the long run. I know people who have made beautiful pots and had them fall apart in a few months. That has to be a real bummer.

So the lesson here, 'Don't get in a hurry when doing this last part of the process'.

Okay, I'll keep that in mind...but I'm so impatient to see them planted!

We don't want to see them until the day count is up.

I'm testing to see if there is any difference - some are in plastic bags, some I took out entirely, and some were soaked for a couple of days, then I took them out. The birdbath has water in it so that's kind of half and half.