Resin Cold Casting for Open-Faced Molds | Rei Cameron | Skillshare

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Resin Cold Casting for Open-Faced Molds

teacher avatar Rei Cameron, Pronouns: she/her

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Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Watch this class and thousands more

Get unlimited access to every class
Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Lessons in This Class

13 Lessons (1h 10m)
    • 1. Intro

    • 2. Background and Class Project

    • 3. Materials

    • 4. Safety

    • 5. Preparing the Mold

    • 6. Preparing and Pouring the Resin

    • 7. Unmolding Our Casting

    • 8. Tidying Up Your Casting

    • 9. Polishing Your Casting

    • 10. Clean up and Other Uses for Cold Casting

    • 11. Troubleshooting Two-Part Resins

    • 12. Issues Specific to Cold Casting

    • 13. Final Thoughts

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About This Class

Ever wanted to create metal pieces for jewelry or costumes but the idea of working with molten metal was too terrifying? Have no fear! Cold casting may be the perfect solution for you. Resin cold casting  involves mixing finely powdered metals with resin to create pieces that appear to have been cast from solid metal. The best part is, you don't even need a foundry!

In this class, you will learn:

  • The cold casting technique, using a two-part resin combined with metal powder and an open-faced silicone mold
  • General tips, safety, and best practices for working with two-part resins
  • How to troubleshoot gooey, tacky, or uncured resin

The versatile process of cold casting is an invaluable skill as it can be used across a wide range of professions and hobbies. I initially learned about it when I had to recreate historic replica props for a science center but it can also be used for:

  • home decorations such as wall hooks and frescoes
  • ornaments, jewelry, and props for theater, escape rooms, or cosplay
  • casting figurines and models
  • wood inlay

Additionally, the process is scalable for use with large, complex molds but to keep things beginner friendly, we will stick to a small one-sided, open-faced mold.

What you will need (downloadable PDF with product links available under the Project and Resources tab):

  • Two-part resin of choice (I am using Smooth-Cast 326)
  • Metal powder of choice
  • Black pigment (optional)
  • Measuring cups
  • Bulb pipettes
  • Mixing sticks, like popsicle sticks
  • Open-faced resin mold of choice
  • Scissors and/or X-Acto knife
  • Gloves
  • Safety glasses
  • Dust mask

Meet Your Teacher

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Rei Cameron

Pronouns: she/her


Hello, I'm Rei. I run a small business called Maker Comet where I pioneer experiences in the art of making. I started out as a research scientist but over the years, have shifted my focus to art and creativity. I helped design and run a maker space which gave me a strong foundation in an array of high-tech tools. I have always been an artist and maker and I am filled with gratitude that I am now able to follow my passion in a professional capacity. I look forward to sharing all of my experiences with you! My information can be found by visiting my Linktree here.

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1. Intro: [BACKGROUND] Hi there, I'm Ray, I'm an artist and maker and the owner of maker comment, where we pioneer creative experiences. I started off my professional career as a research scientist, then as a content creator for a Science Center at which I also helped start a makerspace. For my five-years at this makerspace, I taught classes in art and sewing. I also learn new skills from the incredibly talented artisans, woodworkers and digital artists that were my coworkers. I now teach on Skillshare to bring those same experiences to you. Today, I'm going to show you a technique that I learned while re-creating historic artifact prompts for the Science Center. Checkout this little butterfly. It looks like real metal. Believe it or not, I didn't have to melt down any sort to make this piece. Instead, I used a process called resin cold casting that combines metal powder, resin and a little bit of polishing work to produce something that looks like real metal. In this beginners class, I will teach you this technique, as well as over some basic methods for working with two-part resins, and how to safely work with metal powders. If this sounds interesting to you, then stay tuned for the next video where I'll discuss our class project. 2. Background and Class Project: At my last job I was often asked to re-create prop artifacts that could be handled by the public. This is where I first learned about cold casting in resin. Now I used to also cosplay a lot and I wish I had known about this when I was actively making costumes. I could've made some beautiful auditions like buttons or jewelry, especially for my steampunk attire. The class project will be casting a small charm out of resin using a silicon mold like this one. Now you can use any mold that you like, but just know that cold casting can actually be scaled up for any sized object. Things do get a bit trickier the larger you go and for that reason, we will only be focused on using open face molds as opposed to more complicated molds such as the two-part mold. I wanted to keep this process as simple as possible for beginners. But I may produce a more intermediate or advanced class in cold casting in the future. We will be using a two-part resin for this project, along with some black pigment and a metal powder of your choice. I will be using smooth cast 326 because it cures quickly. But feel free to use your favorite two-part resin for this project. The only resin that I may not use for this would be UV resin because the UV light has difficulties penetrating through the metal powders. I've provided a downloadable PDF with all of the supplies that I'll be using. Be sure to check that out before jumping in. 3. Materials: Hey there, welcome back. In this section I'd like to talk a little bit more about the materials that we'll be using for the class and why I've chosen these particular items. Let's start with the resin. I mentioned before that we'll be using Smooth-Cast 326. This resin is made by the company Smooth-On, which I was able to pick this up at my local Reynolds Advanced Materials store, but if you don't have a Reynolds near you, you can absolutely find this online. Now, the reason I've chosen this particular resin is because it has a very quick curing time of 60 minutes and the working time is pretty short, 7-9 minutes here. We want this to cure quickly because we want the resin to get thick and hold onto the metal particles so that they don't all sediment to the bottom of the resin. When you pour this, you can take the resin that's partially cured or gelled and you can brush it all over the surface of your mold, and that is going to give you a much more even coat of those metal particles. Now certainly, you can use whatever two-part resin you would like to use for this project, you don't have to use Smooth-Cast 326. Just keep in mind that for your particular two-part resin, you'll have to know about when it starts to gel up and that may take a bit longer than Smooth-Cast 326 since this stuff cures pretty quickly. I know from experience working with art resin and some other epoxy resins, they do have a longer working time and therefore take a little bit longer to gel. You may just have to factor that in when you're doing this project and following along. As I mentioned before, UV resin is not a great resin to use for this project, one because it doesn't gel until it's exposed to UV light and even then it's pretty difficult to control that reaction. Two, with the metal particles mixed into the UV resin, all of that metal is going to block out the UV light that's necessary to actually cure the resin. So go ahead and keep your UV resin for a different project and stick to your two-part resin for this and you'll be good to go. The next material that I'd like to talk about are these metal powders. I have brass and copper here and off camera, I have some aluminum as well. Now these are very finely powdered metals, so let me go ahead and show you the brass here. This is brass powder, and as you can see, it is a very fine grit. The copper is similar, they're all similar to this here. They look nothing like the actual metal. If you think about brass, it has a shiny gold finish to it. Don't worry, once we finish polishing our pieces up, it will have that beautiful shine, but this is how it starts off. [NOISE] Now you want to be careful when you're working with this and so the first thing I would recommend is wearing a mask while you're mixing these up with your resin because the dust is not good to breathe. You might also want to wear some gloves, although you probably will be wearing gloves any way because we're working with resin and so it's a good idea. You may also want to wear some eye protection, you don't want to get the stuff in your eyes. Next up, let's talk about the different types of colorants that you can use to tint your resin black. I've got some alcohol ink and here and I've got some powdered pigment, some black powdered. It has a duo chrome green sheen to it, which is fine for this. That's actually not going to show up at all, I'm more interested in just the black powder itself. Both of these are suitable if you're using an epoxy resin. However, Smooth-Cast 326 is a polyurethane-based resin and it reacts really badly to any liquids that you might add to it. If you're using Smooth-Cast 326, do not add alcohol ink into your mix. Stick with a powdered pigment or you can optionally buy a pigment liquid that is formulated specifically for polyurethane resin. I don't actually have any on me right now, I was going to use powdered pigment for mine and that's something I've been using for a while. I don't actually have an example to show you, but if you go onto Reynolds Advanced Materials' site or Smooth-On's website, they have several different dyes that you can add safely to a polyurethane resin. For this, we're adding black pigments to the resin to create some depth. Now this is optional, you don't actually have to add any pigment to your resin, you can just simply mix the resin and the metal powder. But I find that adding a black colorant to the resin or working with a black resin, you can actually buy pre colored resins, gives you a better look in the end. You'll have more of that antiqued color or the antique finish to the piece. This is what I'm talking about with that antique look. This is some resin that I mixed with the black pigment powder, which you can see on the back. There's the green sheen that I'm talking about that comes with that particular powder, which by the way, it's actually black eye shadow that I got a long time ago, but it works great as a resin pigment. Anyway, [NOISE] like I said, for the front, you can't really even see that green sheen and the black really gives depth to the piece. The high points of the resin piece get buffed out and they become shiny, whereas the low points in the resin, so all of these grooves that make up the butterfly's wings, remain a dark color. It's not completely black, it still has the metal powder mixed in, but this is what is going to give your piece that antique look. I recommend using that black pigment, but you'll be fine if you don't actually have a black pigment powder or pigment liquid to work with in your resin, up to you. [NOISE] The other fun thing that you can do is experiment with other different colors. You can try out maybe browns or whites or [LAUGHTER], I don't know. It might be a fun experiment just to try different pigments to color your resin and see how they turn out when you do cold casting. That's an experiment I haven't tried yet, so let me know how that turns out in your projects page if you do decide to experiment with, using different colored pigments. Let's talk about the last few materials that you'll need for the class. You'll need your silicon mold. I'm using this butterfly one with the frames, but you can use any mold that you'd like. You can even use a two-part mold. Like I had mentioned before, things do get a little bit more complicated when you're using a larger mold, but honestly this technique can be scaled up or down depending on whatever size object you want to cast. With a larger two-part mold, you'll have to pour in your resin before it starts to gel and then seal off the opening and then you're going to take it and rotate the whole thing around so that the resin coats the inside. To start off, if this is your first time doing this technique, I would use just a flat mold like this, where the back of the piece is just going to be flat as opposed to a three-dimensional two-part mold. The next piece that you'll need are your mixing cups and a stir stick and probably some pipette. This mold is really tiny, it does not take a whole lot of resin to fill it up. I'm probably going to have to measure my resin out using pipettes for a smaller volume. But if you're using a bigger mold, you can use a silicone measuring cup like this where has the amounts on the side here where you can measure out more. This will hold up to 100 milliliters, but I probably won't be mixing up a ton of resin, so the smaller pipettes are great for that. There's also smaller silicone cups that you can get like this little guy here, super handy for smaller volumes of resin. I'll provide links in the PDF page, that will be in the resources section of this class. I really like using silicone mixing cups and silicone mixing sticks because they're reusable and when you're finished, you just let the resin cure and then you can just peel it right off, so easy cleanup and reusable. You don't have to be constantly buying more popsicle sticks or stirring rods. Finally, you will need some fine steel wool. This is number 0 steel wool, which you can find at any hardware or woodworking store in the sandpaper section. This is, like I said, number 0, but you can go all the way up to quadruple 0 steel wool and that'll work great, so wherever you can find. This is what makes the magic happen. We're going to use the steel wool at the very end once our piece is hardened completely to buff it out and this is what is going to give your resin cold cast a metallic sheen. 4. Safety: Before we get started, working on our project, I briefly want to talk about safety. We are working with resin. When you work with any resin, you'll want to be wearing gloves. Resins are made of chemicals that you definitely don't want to get on your skin as they can be irritating. Always wear a pair of gloves when you're working with resins. Let's briefly talk a little bit about the safety for when you're working with the metal powders. For the resin, you're going to be wearing gloves and it's a good idea to also wear gloves whenever you're working with this metal powder. You will also want to bring along a dust mask and some eye protection. Because the powder is just so fine, it tends to get into the air very easily, and you don't want to breathe that powder, nor do you want it in your eyes. It's a good idea to bring along those two pieces of safety equipment as well along with your gloves. Finally, if you do happen to get a spill when you're working with your metal powder, and believe me it does happen, you want to have a vacuum cleaner handy and also some paper towels to wipe everything up. Start with a vacuum cleaner first and vacuum up as much as you can. Then take a wet paper towel and just wipe off the rest and you should be okay. If you happen to spill either the resin or the hardener or a mix of the two, scrape up as much as you can using a scraper and a paper towel, and then clean the surface using alcohol or acetone. 5. Preparing the Mold: Hey everybody. Welcome to the next section. This is where it gets really exciting. We are going to start in on our project. I've got my mold ready to go here and I've got all of my measuring cups and stirs, and I've got my powder and my resin, and so we are ready to go. Now before we begin, I want to quickly show you how to roughly determine the volume of resin that you're going to need for your mold. It's not going to be exact, but it'll get you close. That's pretty helpful, especially if you have a mold that doesn't have perfectly dimensioned shapes. The frames are square and so you could do volume calculation on that, but the butterflies are a little bit more difficult. This is one method that can help you figure out how much resin you're going to need. I'm going to just start with some water here [NOISE] and then I'm going to pour it into a little measuring cup here with a spout. That's going to help me get it into the mold without spilling, hopefully [LAUGHTER]. Here we go. We're going to just fill up each section of the mold. Oops, too much. That's okay. We'll just going to fill these up loosely. Don't worry about overfilling too much here because I'm going to grab a pipette. I'm just going to pull out some of the extra water from these guys over here, which I overfilled. We'll just add those into these last few shapes here. Looks like that last one's going to need just a little bit more, so we'll go ahead and fill that up. There we go. You don't have to get too precise with this. This is just to give you a ballpark idea of how much resin you're going to need. We've got water filling up our mold, and then what we're going to do is transfer that into one of our graduated resin cups. Try to do this without spilling. There we go. You can squish the mold into a taco shape, I guess, to get all the water in there. Shake it out really well and then you can take a look at where the water fills up the cup too. Because of the angle of my camera here you can't really see, but on mine it's filling up to about 10 milliliters. Try that out with your mold and then that'll give you a loose calculation for how much resin you'll want to mix up for this project. Now the other thing is once you've done this, you will want to towel off your mold really, really well, and especially if you're using Smooth Cast 326 or any other polyurethane resin, because it will react badly to the water [LAUGHTER]. If you have time, it's a good idea at this point too once you've toweled everything out, just to let this air dry completely before you begin [NOISE]. Just knock out all that water and dry it off. Perfect. Then same for the measuring cup. Once you dump out all of this water, either grab a dry, clean one, or make sure that this is really, really dry before you mix up your resin in it. When we come back here in a sec, we will start mixing up some resin and prepping our molds. It looks like we're ready to start working with our resin next. My mold has been wiped out and dried after we did the loose volume [LAUGHTER] calculation. This is ready to go. I also have two pipettes for the resin. One is going to be for the resin and the other will be for the hardener. You want to make sure that you have two for this with your two-part resin, and you don't want to mix those two up because if you dip a used one from the hardener into the resin, then you're going to block your entire barrel or bottle of resin, so keep these two things separate when you're using them to measure out your resin. I might be jumping ahead a little bit here, so we'll talk more about mixing your resin in just a second. The first thing that we have to do is prep our mold. I'm going to get a piece of paper here [NOISE] that I've just folded in half. I'm just going to set that underneath my mold. Because what we're going to do is we're going to take our metal powder and we are going to brush it into the mold spaces here. This can get a little bit messy. Plus any extra that we have, we want to put back into the container, so we can use it again. Off-camera, let me just get my mask on and my glasses here. Here we are back. You can't see it. I'm wearing my safety glasses and my mask, so I don't get any of the brass powder into my face. We're going to go ahead and just start coating the surface of our molds with the brass powder. I just use a brush and we're just going to sprinkle this into the mold, and then just scoot it around with the brush, making sure all of the crevices are nice and filled up with that powder. Don't be stingy because we're going to just put it back into the bottle once we're finished here. Any extra that doesn't stick to the mold will just go back in the bottle. Here we go. Now the reason we do this is so that we have a little bit of extra metal to work with once the resin goes in. We are going to be mixing some of the metal powder into the resin as well. What typically happens is the metal powder, even though it's a fine dust, it will sediment to the bottom surface of the resin as the resin cures, and so that will add a little bit more layering of metals over the top of this dusting coat here. But this gives the resin a little extra surface coat, because at the end we are going to be sanding this, and the more metal that we have coating the surface, the less chance we have of sanding too far and removing all of the metal from the surface coat, which will leave you with black resin. You want to go ahead and do this for each one of the shapes in your mold. I'm just going to start scooping in stuff here. I may speed this part up a little bit because it's not that interesting. If you don't have a brush handy, you can also just tilt the mold and tap. It's quite a bit more messy, but oops. This is why we're working over a paper. Trying to get a little bit of that dust on the edge of these frame molds here, so the edges also look nice. That's looking good. Just gently going to shake that out and there you have it. The mold is now coated with brass powder and then we can just set that aside. Then carefully take this, oops, there goes my brush and then we can just funnel this back into our container [NOISE]. There you have it. Just pop the lid back on and now we are ready to start pouring our resin. 6. Preparing and Pouring the Resin: Onto the resin. What we're going to do now is we're going to grab our two-part resin. This is the plastic. The hardener comes into yellow bottle with this particular system. Your system may be a little bit different if you're not using Smooth Cast and that is fine. Just use your manufacturer's instructions and mix according to their ratio. The first thing is we need to mix this up. I like to do that not by shaking really vigorously because that introduces a lot of bubbles. While I don't care so much about bubbles for this, I don't want foam, I don't need a ton of bubbles because that's just going to look bad. I'm going to take my bottle here and I'm just going to give it a swirl. I just rotate this around in a circle. You can gently invert it back and forth. This is going to mix the resin. Now if you're really worried about bubbles too, you can not shake this and you can just take your mixing stick or a popsicle stick and get in there and stir the resin. That works as well. I'm just going to mix up both parts. You want to do this for both the hardener and the plastic. I'm just going to mix these up, then we're going to start measuring out what we need [NOISE]. Remember I mentioned you're going to need two pipettes for this, one for the hardener and one for the plastic or the resin. Like I said before, it's really important to keep these two things separate. You do not want them touching, you don't want to put the used one into the other bottle because that will start the chemical reaction to harden the plastic and you don't want that because resin is expensive and this system will make up quite a few of these molds so you don't want to waste it. Just be careful keep your pipettes separate. Now when I measured this out, I got a total volume of about 10 milliliters and because that is just such a tiny amount, so I can show you here on my measuring cup, that is the bottom line here. Because there isn't another marking below that for five milliliters, I have to use pipettes to measure out the exact quantity. Depending on the size of your mold, you may have to do the same thing. Now if you're using a larger mold, you may not have to worry about this at all. Just use the gradations on the side of your container for measuring it out. Smooth cast 326 is a one to one ratio resin. Let's say I needed a total volume of 40 milliliters, that would mean that I measure out 20 of the plastic or the resin and 20 hardener. One to one ratio. It makes calculating the amount very easy with the system. Now not all two-part resins are created equal. They may have different ratios that you mix the resin to hardener. Just be sure to use your manufacturer's recommendations. You can also do this by weight, but I find using the gradations on the side of the beaker a little bit easier. I'm going to be using these pipettes here. They also have great aided markings on it. The maximum amount here is three millimeters. What I'm going to do is measure out five milliliters each of my hardener and my resin. I'm going to start with the resin first, then we're going to mix in some brass powder into that and make sure it's mixed up really well. We're also going to add our black pigment to the mix, and then once everything looks uniform and nice, then we add the hardener because smooth cast 326 hardens lickety-split in seven minutes. You have a very short working time to get it right. You want to make sure that all of the additives that we're adding in are well-mixed before you add the hardener. Let me grab the black pigment and we'll get started. I'm back, I've got my plastic here. I'm going to go ahead and use a pipette and measure out what I need. We're going for five milliliters, that means filling up to the three-line here. Then the next row will be to the two. So thick. Try and get as much of that resin out of the pipette before you go to refill it. Now this one will fill up to the two mark. We're about there. Get all that out, give it a good squeeze, beautiful. I try and keep my pipette down low in the container because it does splatter a bit when you hold it up. You want as much of that resin to the bottom of the container as possible so that you get a very accurate ratio of resin to hardener. This stuff is pretty finicky. You really want to go for accuracy here as much as you possibly can. Try and be as accurate as possible otherwise your two-part resin will not cure. Been there. [LAUGHTER] Ask me how I know. I'm just wiping off the container here, so it's nice and neat. Put that back. [NOISE] Now, we can add in the rest of our powder and pigment to this cup. First, let's go ahead and start with the black pigment. I've got my black eye shadow here. I just open that up. We can just tap in a little bit. It's not going to take much. Actually, if I want to be a little bit more accurate, maybe I'll use a stick. Here we go. Scoop up a little bit like so. Here we go. Grab my silicon stir, and we're going to go ahead and start mixing that up so just we break that powder apart. Mix. See all those clumps? This is why you want to do this in the resin first before you add the hardener. You don't want your pigment to look uneven, always do this part first and scrape the edges because again, you don't want clumps of pigment in your final piece, that might look a little weird. Give that a good mix up. Make sure it's nice and even, no clumping. Now's the time to adjust too. If you find that you need a little bit more pigment in there, go ahead and add more. Always start with less because it's easy to add more, but it's impossible to take away. That looks good to me. I'm going to go ahead and grab my brass powder next. [NOISE] Same deal. We're just going to add a bouch that much there. I'd say that's about a quarter to maybe a little under half a teaspoon. It really just depends on how much volume of resin that you are making up. I usually just eyeball this step. Ultimately what you're going for is something that does look metallic and brass so that you can actually see the metal particles in there. It's going to give the resin at this point a gold sheen. We're just going to mix it up really well. That looks a little bit light, so I'm going to add one more scoop of the same amount. Just a bouch like the tip of my popsicle stick here. Add that in [NOISE]. That looks a little bit better, it's a little bit more opaque, which is what I'm going for. [NOISE] That is well mixed. We can put our metal powder away. [NOISE] We can put our black pigment away. [NOISE] Ready to go. Last step, we're going to add the hardener, and that's when the clock starts ticking. Be ready to go. [NOISE] Let me open up my hardener. [NOISE] Same amount here, but remember clean pipette. Don't double-dip. I'm filling up my pipette to the three first. We're going to drop a little bit there. That's why I have a paper covering on your work surface to catch any of those drips. If you do have drips or spills, just have a bottle of isopropyl alcohol handy so that you can wipe down your surfaces with alcohol and it should clean that right up. Always wear gloves too when you're handling this, you don't want to get these components on your hands. There goes my two milliliters getting that as out as much as possible. There we go. I'm just going to wipe my hardener jar bottle clean. [NOISE] Ready to go and now the clock is ticking so we do have to stir, scrape the edges, scrape the bottom, mix it well. Do this for about a minute. Set a timer. You want everything mixed up really well. [NOISE] You also want those metal bits in suspension as much as possible. As we mix here, we're going to mix it until the resonance starts to thicken, because that is going to keep those metal particles suspended a little bit better so that they don't wind up all sinking to the front surface. One thing you might notice too, as you're mixing up your resin is it's going to start to heat up. This is known as an exothermic reaction, so it gives off heat, and that's pretty common. That's another sign that your resin is starting to cure because you can feel it giving off that heat. I can already start to see this thickening a little bit, which is what we want. Now, we don't want it to cure in the cup. Once it gets to that point, give it a good stir one last time. I would even stir it between pores. We've got it pretty much in suspension now, I'm going to start getting it into the molds. You can see how thick that is. Give it another stir before moving on to the next. Got a little messy there. [NOISE] Since I got some in that one, let's just start there, I'll do one more, stir. This is going to be enough for those three today. We'll see if I got a little extra here. I can scrape up to fill that last mold. [NOISE] I'm going to be a little bit shallow with that so we can just move the resin about. That's a wrap. If you see any surface bubbles, you can go ahead and just pop those. Remember, this is just going to be on the back of the piece. I overfill these a little bit. [LAUGHTER] Probably would have had enough to fill that one if that hadn't happened. We'll just have a little bit more clean up at the end here. We can go ahead and just take this opportunity to give it a quick flame. This particular mold is not really rated for torches, its a little bit of a different silicon, so double-check that some molds do not like heat. You can go ahead and just give that a quick surface bubble removal. It doesn't matter too much because this is the backside that's not really going to show in your final piece. Then really we just wait for this to cure. This is going to take an hour to fully set up. I'm just going to just push this to the side, let it do its thing. When we come back, we'll unmold this, and I'll show you the next step. 7. Unmolding Our Casting: We are back and it's been about an hour. I gave mine a little more than an hour to cure and it is solid to the touch. It's not tacky at all. I know that my resin is fully setup and I can remove it from the mold safely. Going to go ahead and do that. Just carefully peel the silicon mold away from the resin and it should just pop out. This is what you'll have. It doesn't look like much right now. It has sort dull, almost plasticly looking metal look to it, but that's okay. We're going to fix that. I'm just going to go ahead and go through and pop out the rest of my charms here. I got a little over. That's okay. We can trim this flushing off with just some scissors or an X-Acto knife if necessary, so it just breaks apart. No problem at all. Got a little messy when I poured that one. Cool. These are looking really great . Nice, shiny, smooth surface. These are going to look so great when they're polished up. We've de-molded all of our resin pieces and the next step is to just trim off some of that extra resin there, and then we'll move on to polishing. 8. Tidying Up Your Casting: I'm back. I've got a pair of scissors here and for all of this here, I'm just going to start trimming that up. We may not even need that. You may just be able to peel the resin off. It comes right off. Sometimes it can be a little tricky to get it started. In that case, scissors are great. Here we go. If you want to avoid this problem, don't overfill your mold. Maybe that goes without saying, but [LAUGHTER] sometimes it's tricky with these really tiny guys, it can be tricky to fill it spot on. My scissors might be a little bit too large to get into those smaller areas. For that, you can grab an X-acto knife and just very carefully carve off those edges. Do this very carefully. This blade is sharp, you don't want to nick your fingers, you don't want it to slip. Just be very careful when you do this. Can't tell you how many X-acto knife accidents that I've had in the past because the knife has slipped so just be very careful. That looks a lot better. There we go. I just did a rough clean up for this, but you can always go back and do that a little bit better than I did here. But just for the sake of time, I figured I would just show you how to trim that up quickly. I'm going to go ahead and clean up the rest of these guys here and then I'll be back with some polishing next. 9. Polishing Your Casting: Welcome back. I have finished cleaning up my various charms here, cutting off the extra resin, and now we're ready to start polishing. This is really the step that makes the magic happen. We go from this plastic look to something that actually looks like metal. For this step, you are going to need to grab a ball of steel wool. Now, this is number 0 steel wool, so it's very fine, it's not like a scotch brite pad that you'd get in your kitchen department. You can actually pick this stuff up at your local hardware store, in the woodworking section where they sell sandpaper. This steel wool goes from number 0 to quadruple zero, which is extra fine and I found that this is just fine you could go down to finer grids, but I honestly haven't seen too much difference or variance in that, so just go for the number 0 fine steel wool and you should be good. What we're going to do, this is very simple. It does take a little bit of time depending on how big your piece is, but this is really the fun part here, so I think I'm going to start with a butterfly. We're just going to go ahead and take the wool and we're going to just start buffing out the metal. Just rub it over the surface in a bit of a circular pattern, and let's put these guys out of the way. As you do this, you're going to start to notice that we scraped away a little bit of that top layer and it starts to polish up and pretty soon you're going to have something that actually looks like brass or very antiqued brass in this case since we used black pigment as the plastic base. I'm just going to do one side here, just so that I can show you the difference between the polished side and the unpolished side. I'm just going to rub that clean. It's a little hard to see with my camera here, but hopefully, you can see that difference this side on the right is starting to take on a metallic appearance, so it looks like brushed metal and the side over here still has that dull plastic look to it, like a child's toy, what it reminds me of. Pretty cool. right just going to keep polishing here a little bit more. Be sure to get the edges as well. Don't miss those edges. Nothing can give away the magic or the secret leaving those edges unpolished, that might look a little weird. [NOISE]. There we go, that's starting to really take on the appearance of metal, brushed metal. It's looking great. [NOISE] I'm going to give the lower wing a little bit more of a polish here. [NOISE] Now you do have to be careful as you're polishing your pieces here because there is a good chance that you can over polish and sand off too much of the surface coat of the metal, so that would start to expose the black plastic underneath. Even though we did add quite a bit of metal into the resonance self which sedimented along the surface here, you still want to be careful because if you over sand, it's going to expose the magic, you're going to start to see black resin. Just be careful and once you achieve that metal look, and it's nice and shiny and it looks like brass, stop. It looks pretty great. I'm very happy with the way that turned out. That's it for the polishing step here and that's pretty much it. It does make a mess so be sure to have a vacuum ready to vacuum up all of the dust from the steel wool and from the charm. Once you're finished, you will have a gorgeous metallic-looking piece that you can use for jewelry, you can make these into buttons and the possibilities are endless. Like I said, it can be scaled up so that you can create bigger pieces like wall hooks or frames maybe you make these into actual frames. I don't know use your imagination. The last piece we'll talk about is cleaning up and next steps. 10. Clean up and Other Uses for Cold Casting: Hey there and welcome back. You made it through to the end. Here we are in the final countdown. It's the final countdown. Here we are with the pieces that I polished up from the last section, and I went ahead and finished off all of them, so now they all have a really beautiful brushed metal look to them. Pretty cool, right? I hope that yours turned out just as brilliant. Now, what you'll want to do once you've finished sanding these up, is give them a quick rinse with water and a wipe down with a towel, and that will remove any extra resin and metal dust from the surface so that you have that brilliant metal shine. Then from here, you can go ahead and add your favorite jewelry findings, you can add these into other resin pieces, or you can turn these into pins or buttons just on their own. You may want to add a little bit of clear resin over the top or a spray clear coat, comes in a spray can, and that'll just seal the surface here so that the metal surface stays looking nice and shiny over time, and with wear. Now that you've gotten a chance to play with this technique, you can use it for a couple of other things as well. We cast our cold casting resin in molds, and like I had mentioned, you can do this at a small-scale or you can make it much bigger and use it for props or wall hangings, which would be beautiful. But the other thing that you can use this for, a little known technique, is for wood inlay. I've got some pieces here, and these were laser cut. At my last job, I worked at a makerspace and we had laser cutters. I lasered in a design onto some wood, and I used the same resin mixture with the metal powder and I filled the design with the metal and resin. Now this is a little bit more messy and it involves a lot more sanding because the design is shallow, usually with this stuff, so you do have to use a higher grit sandpaper to take off all the surface resin, all of the excess. Then once you get it down to the surface design, you can switch over to your steel wool and give it that final polish. With this technique, it is a lot easier to oversand your design, but if you're careful, the results do look surprisingly like you inlaid real metal. For this technique where I used it as wood inlay, I didn't actually mix in black pigment. This was simply resin mixed with metal powder. Unlike these guys here, where we added black resin to give it a little bit more depth. There isn't really a need for that if you're using cold casting as inlay with another material. Just keep that in mind. If you don't have a laser cutter, most people don't, [LAUGHTER] but if you don't, you can also do this same technique by using a Dremel Rotary Tool to carve in a design into your wood piece and then use the resonant metal mixture to fill it in. But in any case, I just wanted to give you another idea for using cold casting. This can make some really unique pieces as well. In the last section coming up, I'd like to discuss some troubleshooting, maybe help you out with some issues that you may have encountered while using your two-part resin. Stay tuned for that next and then we'll get to the wrap-up. 11. Troubleshooting Two-Part Resins: We're back talking a little bit about troubleshooting. If you had issues with your casting today, don't worry, we're going to talk about some of the more common issues that happens with two-part resins and maybe try to figure out what went wrong. The most common issue that most people run into when they're starting to use two-part resins is that their piece sets up soft. It never actually solidifies, or it is tacky to the touch so the surface is sticky. The most common issue is that the resin wasn't mixed up properly. There are two different problems with this. The first is that not enough hardener was used, and the second is that the resin mixture wasn't actually mixed thoroughly. Let's talk about the ratio first. With any two-part resin, you need to be as precise as you possibly can when mixing it up, so that means getting good silicon cups or measuring cups that have accurate gradations on the side. You can also use your manufacturer's instructions for weighing out the resin. Now, the weight ratio is likely going to be different than the volumetric measurements, so just make sure that you use the manufacturer's directions for measuring out your resin by weight. If your resin didn't set up, it's likely because you didn't have enough hardener in the mix, so go back and you'll probably have to recast those. You can wait to see if it hardens up, but it's hit or miss at this point, so you may just want to start over. Now if you have tacky resin where it is solid to the touch, but the surface still feels gooey, or sticky, this could be caused by high humidity in your area. It could also be a bad reaction to an additive that you put into your resin. If you're working in an area that has very high humidity where it's raining all the time, you're going to need to get a dehumidifier to put next to your resin pieces as you work. Maybe use some silicone gel, keep your pieces covered while they're curing, and add in some like a silicone moisture absorber around your piece to remove as much of that moisture in the air as possible. Polyurethane resins can be a little bit more sensitive to things like humidity and moisture in the air, and so if you live in a climate that has high humidity, then you may need to use an epoxy resin instead. In my experience, epoxy resins tend to be a bit more forgiving when it comes to things like high humidity. Now, let's talk about when your resin has a bad reaction to an additive such as an alcohol ink, or a pigment. I remember when I was first testing out smooth casts 326, I used alcohol ink as a tint and it didn't set up. It remained gooey, tacky and it actually just did not harden like a should have. This is another issue. Not all resins are compatible with the different pigments that are available out there. Your best bet is to talk to your local store and try and find resins that are compatible with pigments. I'm lucky I live in a place that has a Reynolds advanced materials and their staff are super-helpful, so they usually can point me in the right direction with picking an appropriate pigment to go with whatever resin I'm using. Failing that, you can always just stick to a powdered pigment like we did for this project. That has no moisture in it, and it is less likely to react than others, like alcohol ink, or liquid gel pigment, so that is an option as well. You can just stick to powdered pigments. You just have to make sure that you mix it really, really well into the plastic before you add the hardener. 12. Issues Specific to Cold Casting: Let's go ahead and talk about some other issues that come along usually with cold casting specifically. If you notice that all of the metal particles kind of sedimented to one side of your mold, then that means that your resin wasn't gelled enough to keep the metal particles in suspension as it was coating the mold. This isn't so much of an issue if you are using an open face mold like we used for today's project. Where this becomes problematic is if you're using a two-part mold, or if you're using a more detailed one-piece block mold. To keep this class as simple as possible, we only focused on open faced molds. However, I might make cold casting for two-part molds into its own class in the future. I hope those tips were helpful. If you have any other issues with your resin, then please go ahead and post it to the discussion in this project, and I will get right back to you. We'll try to work out together what is going on. So good luck with that, and we're going to head into the wrap-up next. 13. Final Thoughts: Well, that about wraps it up for this class. How did your project turn out? Please post pictures of what you made in the project section so that everybody may be inspired by your makes. I hope that you might use this technique for other projects that you might be working on, be it in costuming, or jewelry, or prop making. If you're interested in other resin crafts, I have another tutorial up on how to use UV resin. Please go check that out as well. I will be posting more classes soon, so please stay tuned for that. Thanks again for taking this class with me today, and we'll see you soon.