HOW TO CAST HYDROSTONE PLASTER into a Mold / Mould Tips & Techniques

Hey guys, welcome back to Jon Burns Fine Art. I'm Jon Burns. So today we're going to cast these little guys finally. We have the mold made. My last video was on casting, some casting tips. And this is the original model. It got banged up and beat up a little bit. So we're going to do a casting, pull the casting out, and I'll show how to clean it up. And then maybe we'll throw a finish on it and get it up here instead of the clay model. So without further ado, let's go ahead and get started. Can we get this thing to ding? Say it with me now. One. Ding! All right, here we go. Okay, so what do they say? An ounce of prevention is worth a pound of cure. So I want to talk about how I'm going to approach putting the Hydrostone in here. Got a plug here. This is just a sink plug. Cut me a proper hole there. And I just want to make sure that this is going to stay because this is a straight wall for the most part and less tapered. And when I put that in, you'll see later on that I'm just going to take this and pull that over that edge and then kind of twist that over and put this one under and just pull that taut. Just as a preventative to help make sure that that's going to stay in all the more. They're just bread ties. I ran staples into the back of the board and it's very easy to undo, you know. Simple, intuitive, and it works. So when I put the plaster in here, one of the major problems that I'm looking at is this leg that comes down and hangs over. Because, I mean, not only do we want to get a good casting, make sure that the surface is free of bubbles, that this leg is also going to get thoroughly coated and that there's going to be, you know, a flawless surface in there also. So my rotational casting machine is, first off, underpowered for something like this and also too small. So the alternative is to find the widest point on the base, and we're looking at like roughly 18 inches, and then what you do, you want to mark off both sides, corner to corner. Yeah, so right about there is going to be true center. If you can't find a Tupperware bowl big enough, like a Pyrex lid or something that's big enough, you're gonna have to get a compass. I used a compass, so I just, of course, 9 inches. 18 divided by 2 is 9, so I set the compass at 9 inches and swung it, and I made sure to mark my center hole in case I needed to reference that. But what I'm going to do is put this baby on here. I cut a hole in the middle, and then that way I have a wheel, and in theory, I can roll this and make sure that it's thoroughly coated. But I just want to clue you in before I go any further. I should probably, where is that? I know that's the circumference. I need at least 4 inches, so an 8 inch hole to clear this, just to make sure that I don't hit that. So I'll set the compass again, and I could do it like right here, 4, and then right there. I put this in my squirrel saw, and that's how I cut that. It took like maybe 5 minutes, not a big deal. And this is pretty weak material. This is just like a particle board. And it doesn't need to be anything special, just something that's going to be rigid enough to hold the shape, so that after I pull this in there and plug it, tie it shut, I can just roll this thing and tip it up and tip it back. I will take it on the edge of the table here, and that way, when it's on this side, I can tip it down, I can tip it up, and roll it. So I can make sure that that's going to be completely coated. And the good thing about that is, you know, I don't necessarily have to have a rotational casting machine. I just have this simple machine designed eons ago, and I can make it work for me. I believe this is a half inch board, and this here is also a half inch. So I just need to find screws that are 3 quarter inch or so. I think that'll do it. And then I can just run a couple of those in here after I pour in the stuff. It'll be good. Okay, here we are. This is the next day. It hasn't been a full 24 hours, but you know, that's fine. The plaster sets up pretty quickly. I just wanted to give it a chance to really finish getting hard to cool off. It has an exothermic reaction. So I just left it alone. I've demolded before when the plaster was in that state, and it's very fragile. Right now, there may still be some suspended water in the plaster. I like water-based clay. For those who know ceramics, the clay has water in it, chemically and physically. So the firing process is what eliminates the chemically bonded water, and that's when it gets vitreous or, you know, hard. Plaster, in the same way, it has, you know, you add water to it, and then it begins to bond with it, and it starts the chemical reaction to turn it hard. After it has finished stabilizing, you know, it goes through that exothermic reaction, and it stabilizes. You're going to have any residual water left over, and if you've noticed, you come back to a plaster that's been cast like a week later, and it has a much more like metallic sound, ding ding ding, whereas it has more of a dull thud. That's because there's water that's still in it. So it's its strongest after it's completely set, and you know that it has completely set when the water is completely out of it. So when I was turning this yesterday, I ended up turning this for 30 minutes. It was about 25-30 minutes. I forgot to check my phone after I had started it, so I was like rolling it for a few minutes, five, and it strangely was 25-30 minutes of turning it. It didn't feel like it. Once I got into a rhythm, it almost became a little like, I don't know if the word is tantric, but you know when you get into a rhythm, you kind of forget. So I was able to go inside my head, and I was just kind of working a rhythm with this, and you can tell by the end of it I had worked out a rhythm, and for this particular kind of casting, because you have to understand your mold, I started thinking about the mold, you know, in the beginning, and then by the end of it, once I had the mold, I had like a pattern in my mind of how I wanted that plaster to behave inside the mold. So I was picturing it rolling across the surfaces of that mold, and every time I turned it, I had, because I was thinking about the back, like I wanted it to roll across this back, which isn't as important as the front, but I just give it a couple sloshes, and then I bring it around, roll it on this side, and then I would dip it down and roll it so that the plaster had a chance, because the amount of plaster that I put in here was actually a lot less. So we're going to find out. I'm going to open this up. There was a couple points when I dropped it, and it slammed, and if this hadn't been seized down over the top with the bread ties, I'm sure this would have blown off, and I would have plaster glirping all over the place. So let's go ahead and get this mold taken apart, shall we? One question you might have is, how do you know when this is set? Well, I had a little bit of left over in the bowl, and so I was watching this as I was doing this, and I kept testing. I was wiping my finger in there, and I could see that this had set up, but I could still hear sloshing in here. So I knew that it wanted to eventually, and the sloshing became less and less. So as long as this was wet, I knew I was fine. Once that set up, I knew I really had to start paying attention, and then I could hear the sloshing, and you really don't want to incur a lot of air bubbles from vigorously sloshing, but I could hear it as I turned over. In some spots, I would hear it slosh, and then it got to the point where I wasn't hearing it, and I wasn't feeling it moving anymore, and then I popped that off, and I realized, yeah, it kicked completely. So I had pre-greased this with Vaseline, and that allowed this plaster to come off. There's some areas where it looks like it leaked under, and I don't know, not a big deal. There's plaster in there. I don't see this as being hugely problematic. It looks like it may have bonded to the inside of the wood, but this is favorable because this actually creates a better lip for this for the future. So that's good. You see how that fits pretty well right there. So we'll set that aside. I'm not seeing any air bubbles in this, and that's pretty cool. That's a good sign, I think. Now something you may want to consider is the potential for leaks. If you're casting hydrostone inside of a mold that has a hydrostone mother mold, make sure that you grease up the bottom also because if any spills out, that plaster is going to adhere to this, and then you're going to have to go into the process of taking a sure form and taking that down flat and then maybe sanding it with one of those sanding blocks because, you know, if you don't, you're not going to have a crisp seal. You're going to have to end up either sanding perfectly flat, you know, sand a little, you know, a straight edge or the board. If you don't sand off enough, you're going to have leaks everywhere around it. If you sand off too much, you may only have a leak there, and it's not that big a deal. You can just put Vaseline, like a clump of Vaseline, and then put your board on there, and that'll self-seal. So it's better to over-sand than to under-sand, and it's just unnecessary work. So grease it up ahead of time. That way, if you have spillover, it chips right off much the same way that this just did. Okay, so that's good enough. And if you made it this far in the video, let me say thank you for watching. Some people like to skip through these videos. I do it too, so I don't blame you. It's okay. But if you have, if you find this interesting, I'm happy to know that. And stick around to the end of this video, and maybe I'll give a sneak peek of the next sculpture that I'm going to be doing a mold of. I will be doing some cutting on it, just because I don't want the mold to be terribly complicated. So I will cut her, I call it a her, it's an inanimate object. I will cut the arms off, and I will cast them separately. But you'll see how this will make a much simpler two-part mold, and that's really what anyone and everyone should be doing, is making molds simple and making them so that they can go back together simply. Nothing worse than a complicated sculpture. I'm doing this now so that I don't have to lay the actual sculpture down on something later to do this, because this is going to have to happen sooner or later to get this plug off the bottom. So that's solid. Okay, now I want to be careful because there's a leg in here. Yes, yes, yep, that shouldn't wiggle. So I know that that broke, and the worst case scenario would be that that didn't break cleanly. I prefer a clean snap, because a clean snap, believe it or not, I've had tremendous success with wood glue to glue plasters back together. Either wood glue or just Elmer's glue. And what ends up happening is that the water gets pulled from the glue into the plaster, and it creates a really strong bond. I've had things break again right near where it broke before, but it doesn't break on the glue. So the glue actually holds it better. It's actually stronger than just the plaster. So it sounds like it's kind of like a cheapo fix, but it's actually a really economic and reliable fix. And if people want to give you a hard time and say, well, that's Elmer's glue, or you know, you just tell them, no, it's horse gelatin. Cow gelatin. Okay, here we go. Here's the big reveal. Okay, so the plaster leaks through a bit. This is what I'm worrying about. Spillage, spillage. You see how beautiful this looks? Oh boy, oh boy, that's hollow. Hollow, hollow, hollow. Okay, so I could have backfilled this, which may have been favorable. I still might do that, because this is very, very, very hollow. And I'm scared, because now I don't believe that that leg is going to have a good break, break a leg. And for those of you that don't know what I mean, backfilling is when you just pour more material in to fill up the void. Nothing complicated. You just don't have to go through the trouble of rolling it, because you don't have to worry about air bubbles on the inside of the surface. Oh, okay. That did go solid. That's excellent. And these look like they're clean breaks. And this foot, I was concerned about air being trapped in the heel, or in the toes. Nothing of the sort. The fingers turned out. Very, very favorable. This Rebound 25 is good. Let me just take a minute to pause. This stuff can flex and stretch quite a bit without tearing. I've seen some silicone molds, if I was doing the same exact thing, it would tear. So, I highly recommend Smooth-On, Rebound 25, or some of the mold macs. I did leave slight gaps to give a little more room to flex. And we're free. So, you can see why that took a little more time. I left some gaps right here to just allow it to flex a little more, have a little more room to wiggle. So, there we go. Let's see if I can... I can tell you right now, just lifting this thing, I can tell where the majority of the plaster went. And it's down here in the bottom. Hear the difference? So, there's a good amount of plaster that's set down here. And that's why this plug was solid, also. So, what I might do is just probably drill a hole through the bottom and mix up some more plaster and just pour it in there to make this more solid. But here we go. The air bubbles are so minimal, they're almost non-existent. They look like somebody took a straight pen and just did some pokings. So, this is a really good casting. You can see where some of the... there's flashing. That stuff just needs to come off. There is a little... there is some seam line gappage. And it's more than I would like. But before I go and clean that stuff up, and especially like right here, I want to leave that alone. You know, I don't really want to... I can actually see what the back of that looks like now. I don't want to rub it together until I'm actually ready to glue it. And I don't want to glue it while I'm fumbling it upside down and stuff. But I think that this is a pretty good casting. And there are some spots here, like there was an air bubble in the mold, that cast in plaster. Leave that in there until you get this backfilled. You chip it out now, this thing is so fragile. I mean, it can't be any thicker than an eggshell right now. But this is a very successful casting. And this is where we're at. You can see here, this seam line is elevated. You can see the slight shadow right here. This means that it's not perfectly matched up. Okay, so this shadow just means that it's overlapped. It's not really where I want it to be. You can see that line in the hair. This might clean up okay. Their faces turned out very well. The hands, the drapery, signature. You can see that air bubble that got trapped under the clay. That got warm at some point. That swelled. So I can grind that flat. And this rough texture will make it a lot easier to conceal that. These are the bolts that I used to screw the backing into the original. I can just sand that flat or use that sure form. And here you can see the seam line. Did the seam line come that way? Yeah, the seam line went this way up over. Where am I at? The seam line went right here up over their heads. And the benefit about going through the hair is that's going to be really easy to conceal. And once this is backfilled and completely dried, I can get in there either with a Dremel or some tools like this and just kind of try to round that a little bit. You know, you don't want to just scrape it flat because then it looks like some sculpture that you ended up buying at Target from, you know, out of the country. And we want to try to really camouflage these marks. So that came down. You can see that gap. Most people wouldn't even care about that. And honestly, a lot of collectors probably wouldn't notice that with just a slight little touch up. If this was a wax, you could put disclosing wax on there and cover that up reasonably well. But we're going to try to sand this with a contour to just kind of disguise that a little more. There's some Vaseline that somehow made it through. Yeah, this looks pretty good. And the pinprick air bubbles are not a problem because what will end up happening is I'll just cover that with the bronze acrylic that I used on the clock. So this is successful. I hope you guys enjoyed this. So this will be casting hydrostone plaster in a complex silicone mold with a hydrostone mother mold. If you're interested in seeing more videos like this, please give me a like. Likes aren't reserved for the few. Hand them out like trick-or-treating candy. Be in the spirit of Halloween. And subscribe. Click all notifications, please. And you can finish seeing this clock project coming to an end. I'm so excited. I can barely contain myself. And! And! Here's a big reveal. I don't know how I'm going to do this. Okay, so right now I'm sculpting this piece. The working title is Andromeda and inspired by Alphonse Mucha and some of the old style pinups that kind of like 1950s hair. I will be making a mold of this once it's finished. So this will be in upcoming videos. I don't know when. And I will end up likely cutting her at the arms here on both sides. Cut. Cut. And then casting her as a two-piece and casting the hands as a two-piece. So working title is Andromeda. Once it's cast, I'm going to clothe her in the style of Alphonse Mucha. If you haven't heard of him, look him up. He's fantastic. He was involved in the whole like Czechoslovakia, you know, separation and all that stuff way back. And I'll put like a headdress on her like some of the way that they used to do. Alphonse Mucha used to like putting these models in costumes and wrapping them in very heavy drapes and just making them almost look garish. But it was very attractive and he used them on like posters. Back in the day, he was kind of like a graphic artist of such. For example, here's an Alphonse Mucha. This is in my studio. So that's in the spirit of Alphonse Mucha. You can see how she's just kind of wearing like a pin in her hair. But this is where we're at. And this is just a little sneak preview. Thank you guys for coming along on this. If you're interested in seeing molds or anything like that, please leave a comment in the description. I appreciate it. You guys are great. And don't forget, the materials are listed in the description so that if you are interested in purchasing some of the items I've used in making this video, find them there. They'll take you over to Amazon and they'll be in your cart. If you load them in your Amazon account, they should be in your app when you go to your app. That's what I wanted to say. So you guys take care. Appreciate you. All right. John Burns with John Burns Fine Art signing off.