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valolson1

Silicone Mold Questions

16 years ago

I haven't posted for a long time because I got "tufa-ed out" this summer. Made many, many leaves and even attempted a silicone mold because there are no big rhubarb type leaves in the desert where I winter.

My question may be stupid but here it is. What is the necessity of making a plaster mold before making the silicone mold. I just used one of my tufa leaves. The only problem I had was that I used Murphy's oil soap and I had a lot of sticking problems when peeling off the silicone layer.

So, can't we just leave off the POP step and make a mold directly from one of our casted leaves? And, if we do, does anyone know of something we can coat on that will create a smooth release when taking off the silicone layer.

For the actual mold, I used the "cheapie" latex/silicone caulk tubes that were about $2 apiece at Home Depot. I used about four for a medium-sized rhubarb leaf. I would really like to make another larger leaf mold but want some ideas. I don't mind investing in quite a few tubes of silicone, but want it to release smoothly from the original tufa leaf.

Comments (7)

  • 16 years ago

    First let me say I'm no expert but I did what you did. The first leaf I did pealed off great (last year). The last one didn't peal off as nice. So I'm thinking it was because the turfa leaf I made it from wasn't as nice. The other one was not turfa but a quikcrete sand and topping mix product. Which is a smoother texture. I would guess the POP step is if you are using a real leaf. Did you use 100% silicone? I pd $3.97 for mine at either Home Depot or Wal Mart. My only other thought is that maybe the Murphy's oil wasn't as thick in the spots that stuck. Kathy

  • 16 years ago

    Thanks, Kathy. Your comments give me some ideas. I don't like using the POP because it's just too expensive for a big leaf. So, I think I'll use a mortar mix or a quikrete and sand mixture, for that smoother finish. The latex/silicone mold actually turned out well, except it took me an hour to chisel it loose from the casted leaf. So, I'll keep trying without using the plaster of paris, and I'll use lots of Murphy's oil soap. Thanks!

  • 16 years ago

    Do a search on this forum for "pop". There's quite a bit of information but I don't know if it gets into the "why" of using pop. Also try to use the e-mail link for Buddfly and see if you get a reply. I think back then that Buddyfly was the pop master. I made silicone molds from cement castings. You can use vaseline, lots of Murphy soap or seal the cement casting with varnish or polyurethane for a release agent. I think I remember reading that the tubes of silicone sealant worked fine but it has to be 100% silicone. You can probably do a search for silicone molds here too. I've used cheese cloth between layers of silicone for a stronger mold. That's lots of information on making molds at Smooth-on. I use some of their products for mold making in my silver casting class. Too expensive for cement leaf casting. Billie

    Here is a link that might be useful: Smooth-On

  • 16 years ago

    Maybe I am not understanding the question correctly, but...

    Since the silicone mold is so flexible, isn't the POP the SUPPORT for the silicone?

    Sue

  • 16 years ago

    Belgianpup, you are actually making the mold from the POP. Use sand to support the silicone mold to make a turfa leaf from the mold.
    If you make a silicone mold from a turfa leaf that will be your support. I have not done the POP thing but this is the way I think it is. If you make the mold from a leaf you need the POP first to get the neg mold(which will be the same as the turfa leaf) and then you will make the silicone mold from the POP leaf. My guess is that making it from the POP is when you have a really nice leaf you want to reuse. I make the silicone mold so that I have something to work with because there are no leaves available. Such as the orig. post winter in the desert. You will use sand for the support of the silicone mold the same as you would a real leaf.. Hope I haven't confused you more. Kathy

  • 16 years ago

    I actually made a silicone mold and it WORKED! I just used one of my larger hypertufa leaves and used that instead of the POP (plaster of paris). I find POP hard to work with and the cost is prohibitive when making a large leaf. So, anyway, I used turtle wax on the tufa leaf. I coated it liberally and really got it into the leaf veins. Then I purchased a number of silicone caulk sticks. They were about $3 each at Walmart and I used about six of them for a large leavf. I used an old plastic credit card to spread the silicone around. (Even if you use a current credit card, the silicone washed off easily). I let the first layer dry and then put on the rest of the silicone a couple days later. I let it dry thoroughly and carefully peeled it off the tufa leaf. I had to dig a little to get the main vein out, but it all came out intact. I made my first leaf out of the mold. I sprayed the silicone mold with a non-stick spray and then placed the mold on top of the plastic-covered sand pile, just as I would it I were using a real leaf. I let it sit for a couple days and then unmolded. It worked great and it will do until summer arrives and I can use the real thing.

    I still have a residue of turtle wax on my original tufa leaf but when you wire brush it, it gradually comes off. And, besides it's a nice light green and actually looks pretty natural, especially when wire brushed. I plan on putting a little reddish wood stain on top, and it will look just fine. It's all about experimenting...and this one worked.

  • 16 years ago

    Yea, for you. I knew you could. I hadn't thought of a credit card to spread the silicone. I use disposable gloves. If you dip your fingers in warm soapy water it works ok. I'll try the credit card next time. Wish it was warm enough here to play. Kathy

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