How big are the leaves? Why are you using fortifier - If the leaves are 14 - 20" I use fiber drywall tape. I have only made about a dozen or so leaves and have never used fortifier.
Many thing could effect this? Did you add the same amount of water both times. I would guess that the fortifier may have had an effect. You removed a lot of water and replaced with a thick gooey liquid- I use portland and sand - not "crete". I mix a small batch, enough to make 2-3 hosta leaves. If I make a big batch, my mix will start to dry a little. Why do you want to remove alkali, are you planning to use in a water feature with fish? I just paint my leaves -

Good luck Mike

I've tried several different recipes trying to find one that doesn't leave little holes and/stick to the leaf. The acrylic fortifier was one of the ingredients I've read about, and that was the approx. proportions recommended--btw, it's not thick at all--more like glazing liquid. And I am using portland-- I know it's not really concrete unless you add rocks or something. It's starts to get quite thick even when I"m only doing 2 or 3 small leaves, but maybe I'm taking extra long to pat it in place. I thougt you needed to get the alkali out so the paint would stick better? I have noticed that the leaves made with the acrylic don't seem to leach alkali the way plain cement does.

1 part portland 2 or 3 parts sand, mix with water until it is like thick paste and apply in small quantities to the bak of the leaf. Hosta leaves are good to start with, nice smooth edges. I also found that a plastic knife works well to make the edge of the mix smooth. Thats it K.I.S.S. -----
I have bubbles - If it really is a problem - not for me - but if it is, after done - mix a paste slurry of portland and use your fingers to apply. Lighly sponge. It should be smooth.
Mike

When you rub in the slurry, how do you keep it from filling in the veins and details? I've had a real issue with the mixture sticking to the leaf--it has a sort of wet sand texture when I peel the leaf away. It didn't do with morning glory leaves or poplar, but does it pretty consistantly with the paulonia leaves and mulberry that I tried. Wondered if maybe those have more sugar in them, since I read somewhere that keeps the cement from setting. Maybe next spring I'll try making some silicon molds and see if I get better results.

good questions -
very small quantities of mix. ALso use small plastic knife to apply, then sponge off gently.
before you go to the expense of silicon - try Hosta's
they are very easy to work with. I do have some leaf parts ocassionally stick, but have better results if I remove leaf after 24 hrs

I just got some acrylic hardener and haven't tried it yet. Other concrete artists have said it really cuts down on surface abrasion.

Is there any info on your bottle about setting time?

Also, warm water will speed up setting time, just in case you used it. Cold water will retard it. But keep your speed up when working with concrete, and don't get sidetracked.

My tap water is acidic and heavy in iron, so I am changing from it to distilled water for mixing my concrete. I am suspicious that the condition of the water is the cause of those stupid holes.

Two things I've discovered about using leaves as molds: Any remaining leaf parts will rot out with weather; and once they've hardened for a couple of days, I will put them in the dog's swimming pool (small, rigid, plastic, $9) to soak. This last prevents the drying out problem that I have in summer, and helps rot out the leaf parts. A soft brush will help dislodge the leaf parts, too, after they are soft.

I don't know that acrylic alters the alkalinity of concrete all that much. If it's important, like I'm making planters to hold acid-loving plants, I will soak them for a goodly period to make sure to leach out most of the alkali.

I guess I should make a small planter and plant an acid-loving plant in it without soaking, and see if it kills it. Then I would know!

Sue

bizbet, Arcylic fortifier shouldn't speed up cure time. It also shouldn't have any effect on bug holes("find one that doesn't leave little holes"), even professionals get bug holes. I like them, makes the leaf look more natural.

Belgianpup/Sue, How are you?!!! My computers been in la-la land.
I've planted in a new planter right away and had no effect on the plant. The main reasons I flush out the lime is because it can burn someones skin if they pick up the planter while it's fresh and wet and it may be someones prize plant and you just don't want to take a chance. It doesn't take that long to flush out the lime if you use a water bath. I unmold most planters in 24 hours, gently clean or carve them then place them directly in the water bath. Just make sure you change the water every day. You should have a lime free planter in 3 or 4 days. I plant most of my planters in a week to a week and a half from the time I make them. Billie

The bottle never said anything about a setting time. When I said holes, i really meant air bubbles. Are you getting real holes? I've not had that problem. And at the moment I have a leaf sitting on the drive way, where it's been since mid september. I have soaked it ,dried it , let the rain and sun have their way, and scrubbed it with a stiff brush, and it STILL has a good sized patch of leaf on it that won't come off. Fort'ly it was a test leaf, and not one I really want to use for anything!

Somewhere, sometime, a guy said that when you're mixing concrete by hand, to stir it with the stirrer held vertically. I don't know if this is true.

When I mix it, I add about half the water that I expect to be adding, mix it so it's all evenly damp, then start adding more water in small amounts. I mix it very well with gloved hands, and I don't have air bubbles. Maybe spending a little more time mixing???

Sue

bizbet, air bubbles aka bug holes, small little holes over the surface. Most people get them but not all the time. I'll try to remember to take a picture of a pile that I have down stairs. I think 2 out of 25 or 30 have tiny holes. You can fill them with a slurry of the same mix that you used to make the leaf. Certain real leaves will stay attached to the cement leaf for a long time. Leaves with hairy backs and thin leaf structure are big culprits. After a leaf is fully cured, and it's thick enough, you can use the jet spray from your hose to "power wash" the real leaf off. If it's not fully cured or thick enough you'll blast a hole through it, remove detail or blow apart the whole thing. I've done that. Sometimes the air bubbles/bug holes are created from tiny air pockets on the surface of the leaf or from working the mix too much on the back of the leaf. Billie