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fleur_gw

Questions re concrete cast leaves.

Fleur
18 years ago

Mom, kids 9 and 11, grandmother and a friend cast concrete leaves yesterday and are awaiting "unveiling" tomorrow. During the course of our experiment, several questions arose and I hope someone can answer.

The recipe we used was 1 part portland to 2 1/2 white sand. I'd heard that adding Elmers glue can be added to strengthen the concrete. Elmers permanent or school glue and when do you add it? How much to perhaps a gallon ice-cream bucket of mix? How to test mix for enough water? I think ours may have been too runny. Or perhaps we didn't wait long enough before applying it to the leaf backs. Small cracks seem to be developing in one of the leaves. Anyone have any idea why this happened? We did use fiberblass tape to reinforce.

The completed casts were covered with saran, then newspaper to keep the sun off. Would hot sun have been bad or good? The castings were misted several times since completion and will get more til we uncast the leaves. Can we continue to mist to "cure" them? Or should we leave them in a bucket of water for a week or so to cure before painting? (We have two that are too large for buckets.)

Next comes the painting. I need recommendations on how to proceed. I think we'd like to use several colors blended together. We have oodles of Apple Barrel acrylic craft paint. Can we dilute this and use on the leaves? I understand we can also use water-based house paint. Is this correct? Do we do the veins first? Then what? Can you seal as soon as the paint is dry or should we wait for a day or so?

I've seen so many great leaves on links to this forum, I'd really like our project to have a happy outcome and a positive reinforcement, especially for the kids.

More later as the project unfolds.

Comments (25)

  • buckyforce
    18 years ago

    WoW! Good for you, diving into this addictive adventure! You asked lots of really good questions!! I will endeavor to impart what knowledge I can lend and am SURE that the wizards on this forum will add much more! I hope I answer some of your questions....(deep breath) here goes!

    Your portland/sand mix sounds fine to me! Your finished mix should be about the consistency of dry-ish mashed potatoes, believe it or not. If you want to add a bonding agent ("b/a")(which strengthens the mix) I would add about 1/4 cup of b/a to the first cup of water you add to the portland/sand. I wing it, I just pour - this is not an exact science. Add more water if the mix is too crumbly, but stir, stir, stir. Before applying the mix to leaves, thump the bucket on the ground a few times. This will force a lot of the air out of the mix, Air = holes on the face of the finished leaf, the fewer the better! Once you are happy with the consistency (dryer than you think...experiment before adding more water by grabbing a glob and patting it in your hand. You will be amazed at how it becomes more liquid, before your very eyes!) Then pat a glob on the leaf, as close to the center of the leaf as possible as it "flows." The more you play with it, the more you will see how it behaves. As you gently pat the mix on the leaf, you will see air bubbles rise...keep patting, this is a good thing! Don't be afraid to add a small glob and pat it into the other should a bald spot appear where you have been patting as the mix flows. (Does this make ANY sense?)

    By all means, do this in the shade!! Concrete "cures" (chemical process), paint dries (evaporation). Direct sun, and heat, will interrupt the chemical curing process of concrete causing cracks to form. Plastic covering will help. It is just easier to cast in the shade.

    The leaves you cast that are too big for the water bucket, how big are they?...If you cast leaves bigger than your hand, you need to think about reinforcing them with metal, depending on what you plan on using them for. But one step at a time.

    Let us know how your smaller leaves turned out! I am excited for you all! How much fun you must be having!

    Painting is next!!

  • Fleur
    Original Author
    18 years ago

    Thanks buckyforce,

    We may be in trouble. The largest is 30"x24", next is 21"x18". (Regular and ornamental rhubarb.) Both of these were reinforced (all were, actually) with the fiberglass tape. More on the larger ones. The smaller ones are in the neighborhood of 10 or 12" by 6 or 8". Should the larger ones be allowed to cure longer than the suggested 48 hours?

    The adults more or less decided that if any break, we'll have material to practice painting. Nothing will go to waste. In for a penny, in for a pound re the large leaves.

  • butterflybush
    18 years ago

    The "set up" time is usually 24 to 48 hours, concstantly misted very wet,the "cure" time has been as long as possible, up to 28 days, keep the concrete consistantly wet. "Any" dry out time weakens the concrete. 28 days in a water bath will strengthen the conctrete. Fibers added into the mix will help prevent small cracks. Larger leaves, thicker they must be, with reinforcement fiberglass tape and/or wire.

  • Jilly_W
    18 years ago

    I have been making leaves from rhubarb since early last year. I use the same recipe as you used, or a sand mix [when I am lazy]. I don't use anything else in the recipe like glue, and I don't use any reinforcement. I have had no problems at all with the leaves. They are unmolded 24 - 28 hours after casting, and once the leaves have been cleaned off the cement, which can be a royal pain - and the edges are cleaned off, I put them in a water bath for 4 - 5 days. I use a large plastic container, or my laundry tub, even a kids wagon as a bath. As my leaves are for decoration, I do not cure them for any longer.

    I paint them with acrylic craft paints, and seal them with three separate sprayings of verathane for outside use.

    Jilly

    Here is a link that might be useful: Leaves

  • Belgianpup
    18 years ago

    I wouldn't use Elmer's glue. It is rumored that people do use it, but it isn't really waterproof.

    I use what looks like white glue, but is actually a latex polymer concrete product: Hornweld. I love it! The only place that I've been able to find it is at commercial building materials places (Mutual Materials), although other places may carry it.

    It's summer -- find one of those $6/4ft diameter rigid plastic wading pools for your large leaves. Don't worry about algae -- the alkalinity from the concrete apparently prevents it, so the water stays clear and clean even if you leave the leaves in there for a month.

    Sue

    Here is a link that might be useful: Mutual Materials, Idaho

  • tufaenough
    18 years ago

    Quick! Someone better tell Tango to stop using Elmers.:)

  • Fleur
    Original Author
    18 years ago

    Thanks to all for your wonderful responses and suggestions. I've uncast 6 of the nine leaves we did. Hosta leaves and one rhubarb came off just fine but one rhubarb is stuck to the cast tighter than white on rice. Currently it's soaking and occasionally I go out and try to losen more of the leaf. I think I'll use a plastic dental pick and try that. All had a fair sprinkling of bubbles. Any idea how we can avoid that in future projects? I don't think we'll mind the bubbles and they'll become less noticeable after they're painted. Maybe we'll fill them with iridescent paint and pretend they're drops of water.

    All six of them are now relaxing in a waterbath. Is that step really necessary? I read both the Better Homes and Gardens May '04 article on concrete leaves and the Garden Gate article and neither of them mentioned curing in water for ANY length of time.

    Not to find the courage to unmask the larger three leaves. Is there any harm in letting them set and mist for longer than 48 hours?

    Another question came to mind earlier. If I choose to embed a narrow diameter piece of pipe or tubing in the back (to thread wire for hanging through) how do I reinforce it and how thickly should I cement over it. Should I reinforce over it with something like chicken wire? Seems the more I learn, the more questions I have.

  • Belgianpup
    18 years ago

    When you form the wire to put it in the back, bend it into a spiral or something that will grab the concrete. Straight wires have been known to pull out under the stress of weight.

    The waterbath often isn't mentioned in magazine-type articles for some reason. But plain cement+ water + whatever is probably strengthed simply because it doesn't get a chance to dry out, which can weaken it in the earlier stages of curing. OTOH, professional concrete artists want their creations to last. Magazines probably figure that all you're doing is making a small trough for succulants or a stepping stone, and it isn't really critical that they survive. When a professional sells a piece of artwork 12 ft tall and it cracks or delaminates, it's a BIG DEAL for him.

    Don't use the waterbath if you've used a latex polymer as an admix, it will WEAKEN the concrete. I don't know about acrylic.

    Personally, I've let leaves stay attached to the concrete until I get around to removing them, and sometimes that's two weeks. I have a smaller Gunnera leaf sitting in the entry (doesn't everyone have concrete leaves sitting by their front door?) that I think still has some leaf debris on it. So, when I get around to removing it, I'll get around to removing it. It's only been there for a few months.

    Somewhere (maybe here?) I read that iron in the water can cause those bugholes. On my next leaves, I'm going to try distilled water and see if that makes a difference. If you're using Pam or something, be sure you only apply a thin film to the surface, or globs can show up as holes.

    If there is an experimental forum at GW, this is it. We surely don't have all the answers, so if you figure out something interesting, we all want to hear about it!

    Sue

  • Rainsend
    18 years ago

    I had a few cast leaves come out with little holes. These were leaves that I had cut the day before and had soaking in water. Before I cast the last bunch of leaves I dabbed off the water with paper towels. These have no holes. I dont know if the water is causing the holes but since this worked for me I will continue to make sure the leaves are dry. All the leaf casts that I have done on fresh picked leaves have been fine and these were dry.

    Maybe this will help. It works for me.

    If I wait longer thank 24hrs to pull off the leaf (or if the leaves are in the sun) I have a more difficult time removing the leaves. I found that if I wait another day or so and soak the leaves in water , I can use an old toothbrush to remove the leaf. A toothpick or stick to remove the stem part works fine too. Even spray from the water hose helps.

  • rickharmer
    18 years ago

    About those bugholes-I did a pour yesterday,following my usual procedure,save one:after applying the mold release,I didn't wipe the molds down,so that the coating is VERY thin.Result?A LOT of little holes.For me,lesson learned!
    Cheers

  • LittleandLewis
    18 years ago

    Can someone tell me what month the Garden Gate article came out?

  • mudwitch
    18 years ago

    Little and Lewis... I have a copy of that mag. there is no date that I can see on the issue. they publish bi-monthly Feb, Apr. June... I believe, this one was April. perhaps if you go to .. www.gardengatemagazine.com they would tell you. I saved the issue, mainly because it upset me that a picture was shown of the person making a leaf with bare hands.

  • gardenbrat53
    18 years ago

    Here is a link to the GardenGate article on leaf casting. Deb

    Here is a link that might be useful: casting leaves

  • Belgianpup
    18 years ago

    Quite a responsible article, no gloves, no mention of using a mask.

    Shopping list just says "2 bags of concrete" Â it isnÂt until you get to the actual instructions that they specify patching concrete. ("Honey, what should I do with all these rocks?")

    "If the leaf you want to use has a hole in it, no problem. Just cut a piece from a different leaf and make a patch." (And it will look like a patch)

    Lift the leaf, turn it over & remove the leaf, turn it over AGAIN & remove the ring? Why not remove the ring first, so you donÂt have to keep handling it?

    "It's important not to let water sit in the birdbath until that week is complete." (Personally, IÂd rather let the birdbath set in water, unless this concrete patch contains some kind of admix that shouldnÂt be left in water. But they don't mention that was behind their thinking.)

    Pick! Pick! Pick!

    Sue

  • Fleur
    Original Author
    18 years ago

    Little and Lewis, et al
    I think it was a promotional, complimentary copy. I got one ages ago and again recently. You can see the article on the GGM website.

    Here is a link that might be useful: Making a Sandcast Birdbath

  • mudwitch
    18 years ago

    Thank you for posting the link. I was surprised at the amount of info at the site, much more than in the magazine. Maybe that was because it was a complimentary copy.They sure have pretty garden pictures though.

  • rcp1959
    18 years ago

    Hi I use vnyil concrete pacther from home Depot 8.95 a bag.Mix with water to about a thick malk shake. put on your leaf abotu 1 and half inch thick works great.for stepping stone bird bathes or what ever.

  • Deenap
    18 years ago

    So, from what I'm gathering, you should soak the casting after you peal the leaves off in water? For how long?

  • Blooming_Stone
    18 years ago

    One of the concrete "rules of 6" is six days wet/moist. 28 days is the amount of cure time, after that it's negligible, so is perfection is what you want - 28 days of misting or soaking in water. That way the most available elements possible bind with water to make the strongest product.

    I'm all about superlatives - apparently!

    Mercedes

  • Fleur
    Original Author
    18 years ago

    Well, I've done several projects since my first inquiry. I used a hosta leaf, appropriated from a friends garden while he was on vacation, but the mix must have been too dry for it had some surface bubbles and mild flaking of surface concrete. The next effort, a crambe leaf, used a looser mix but it was so runny, I had to blot some of the moisture that ran off the edges with paper towels. It developed a crack along the midrib before it was dry. I didn't unmold it at that time.

    In an effort to reduce surface bubbles, I next tried a leaf with some Sakrete Fast Setting Cement Patcher. It set up so fast, I could hardly pat, pat, pat. It did have a nice surface though. I used some of it to patch the crack in the prior day's crambe leaf...reinforced with fiberglass tape. That seemed to save the crambe. I won't be using that again, though I wonder what would happen if I added some of that to the standard 1:3 mix.

    Next I tried a couple of test leaves with mortar mix to see if I could get a smoother surface with fewer bubbles. I made a thin cast, only about 1/2 inch thick. I thought it had a very nice surface with few tolerable, small bubbles and the consistancy seemed to be finer than when I used the silica sand in my original project. I'm very tempted to try a large project with the mortar mix but that raises a whole bunch of new questions. Is it as strong as the 1:3 portland to sand mix? Should I use a fortifier? Do I spray and cure it as other mixes? I really hope someone can comment on the mortar mix.

    Now my last question is really a dumb one. When do you paint your leaves? After they've cured. What if you paint them before? I've seen threads where someone showed a picture of a just unmolded leaf and the next day showed it painted.

    Thanks, everyone, for sharing your thoughts and expertise. These projects have been so much fun I'm WAY behind in my housework, not that I care, mind you. Fleur

  • Dena6355
    18 years ago

    According to the guys at Salmon Bay Sand and Gravel in Seattle, true mortar mix is often a 1 part cement:3part sand:1/4part lime. A common mortar is 1 cement to 3 sand.
    So if you like the results using your mortar mix I would think you are good to go with it.
    I have suggested to others that if you are interested in trying leaves without having to buy the big bag of cement and sand only to find this is not for you, you can try the small 10# bags of quickrete mortar sold at Lowes for under 5bucks.

    housework does get in the way of cast leaves and other much more important projects and ideas!
    Happy casting,
    Dena

  • Dawn Field
    8 years ago

    I see these comments are all from years ago, so I hope someone responds. I am trying these leaves with sacrete top & bond. Do I have to cure that full 28 days before painting? I am using these for an outdoor fountain. Is the water bath necessary? Nothing on the top & bond label indicates the need for a water bath to cure. Can someone please help? Thanks




  • Mike Larkin
    8 years ago

    I believe the top n bond should work. I typically use portland and sand. Cement gains the most strength while curing during the 1st week, ( if temp is over 50 o F) During week 2 (if kept damp), it will gain less strength ( than week 1) , 3rd week less strength. If you are making something that needs to be strong, cure for entire time. I have tried to keep my leaves wet for about 1-2 weeks, My curing process - I wet frequently and then cover with a garbage bag. Do not let it dry.

    Then if I want to use the leaf for a bird bath I will rinse several time with water. Or place in a tub of watewr for a few days. If you plan to seal, use the correct type of sealer. I believe there are sealers for new cement and one for cured cement.

    Mike

  • Dawn Field
    8 years ago

    Thank you. I covered the leaves with the top & bond yesterday. They are hard now and were partly dry until I started reading more of these articles and realized I needed to get them wet. I will take your advice and wait a couple of weeks before adding the color. Some of the articles have them painted after 2 days. The one I like the best is more of a wash with diluted latex and acrylic paint. But they all recommend sealer and I assume that would halt the curing process, correct?

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