I made my first silicone mold
I received my Smooth-On Mold Max NV-14 NV last week and have been working on my sculpt so that I could create my silicon mold today. I was very anxious about creating the mold, as I've only done resin casting in silicone molds that I purchased. Leading up to making my mold, I watched a lot of Punished Props videos. I totally recommend watching Bill's video's if you plan to make a silicone mold. He has a lot of great content and tips and tricks. Last week, I decided that I wanted to make a two piece using the Mold Max NV-14. Today, before I made the mold, I decided since it was a very flexible silicone that I would make a one piece mold and slice it down the back to pull the piece. I started the process at 11:00am by building up a Dam around my piece using cardboard and gluing it down to the surface around my piece. Others cover this process in more detail so I won't go into it here. I then roughed out how much silicone I thought that I would need and measured out my 100:10 ratio. I figured it would take me roughly 6oz. I was very wrong. I poured it in and realized I was extremely short. I quickly mixed up another batch using new containers, mixed it up and poured it in. Ultimately, I had to mix up 4 batches and pour them in to make the mold. Bill recommends starting small and working your way up. I did absolutely the opposite and spent the day worrying that I just blew $91 on a silicone mold that may not work. On the bright side, I do have enough silicone left to make a small mold. :-)
I waited nine hours before I cracked open the mold and pulled my sculpt out. It was a hybrid of hard materials and oil based sculpting clay that doesn't harden. This is why I didn't do a two piece mold, as I realized I would not be able to do the process with clay on clay. Ultimately, I was unable to pull my master out of the silicone, so I cut a slit down the back roughly 3/4 of the way down as I had seen in some videos. This allowed me to pull everything out. I was pleasantly surprised to see the mold turned out just fine. As a side note, I followed the double mix method for the silicone to make sure that is was mixed well enough and will absolutely follow that process moving forward.
Once I removed the sculpt, I thoroughly cleaned the mold with a brush and isopropyl alcohol. All the while, thinking I should have done a brush-on mold or a two piece. My hope at this point was to be able to get a single perfect cast out of the mold so that I would have a good master to create a new mold from. Obviously, I need to pull more pieces out of this mold just to cover my cost.
Once I got the mold thoroughly cleaned, I wrapped masking tape around the outside of the mold to keep the seam closed, as I have no rubber bands as you will see others using in their videos. I sprayed some Ease Release 200 into the mold and let it dry and then made sure that the seam was smooth on the inside. Since I had such an issue with determining how much silicone to use, I decided to figure out how much resin I needed ahead of time. I did this by pouring rice into my mold until it was full and then dumped it into a container. I dumped it into a measuring cup and transferred the rice to another container. I determined that it was roughly 1.6 cups, so I decided to round up to 2 cups just to be sure. One thing that Bill mentions in his FAQ video is he always has overflow molds that he can pour excess resin into if he has too much. I decided that since I was unsure as to how much I may actually use, that I would prepare most of my molds as overflow, just in case. This was a good thing, since I actually ended up using all of them for overflow. I used Smooth-Cast 300 for my mold and all of the overflow molds. I worked quite well, so at this point, all I had to do was wait.
I waited 15+ min and touched the resin in the mold that I made. It was quite hot, so I decided to go ahead an de-mold and trim up all of the smaller pieces before de-molding my big one. After another 15 minutes, I got around to de-molding my new piece. I was anxious and hopeful that all turned out as expected. I pulled, and tried to get the piece out for around 15 minutes until it finally let loose. As I mentioned earlier, I probably should have gone with a brush-on silicone, but I needed to use what I had. Once I finally got my piece out of the mold, I was quite happy with the results. Ultimately, this one will be my new master so that I can make another mold in the future. There are a couple bubbles in areas that makes sense there would be, however, overall, I am very happy with how it turned out. While this was an expensive learning opportunity, I now know much more than I did, and I have hands on experience.
I totally recommend that anyone thinking about making a mold to pick a simple piece that can be a one piece cast for your first project. Once you get the hang of it, it gets easier. I do plan to use this mold to make some Metal Cold cast pieces, even though it's not a perfect, It produces a very nice piece. At some point, I'll make another mold that will be easier to remove the piece. Since the first casting I pulled from the mold was flawless except for a couple bubbles, which I can prevent on future pours, I'm calling this an expensive success.
I plan to have rusted iron cold-castings for sale at the art fair coming up on September 17th. If you are in the Lexington, KY area, please drop by High on Art and Coffee.