I decided to try my hand at casting a mold the other day. I keep reading articles about it online and thought, what the heck. Most of the articles on casting and making molds quickly devolves into how it is evil and wrong to copy others IP but interspersed between this bickering there are quite a few good tutorials out there if you look around.
Once I had made up my mind I headed down to Hobby Lobby and picked up an alumilite starter kit. I read through the directions and it seemed easy enough. You mix the silicon up, pour it over the part you want to mold, remove the item, and then pour it full of resin. Great. Sounds easy.
The first issue I ran into is that you mix the catalyst and silicon by weight. We are talking about really small weights here. The catalyst that came in the starter kit was only 10g worth. The good part was that silicon was premeasured to where I just had to mix it all together. I was hoping to get one or two batches out of this kit so that was kind of a let down.
For my test piece I grabbed a few armless minis out of the bitz box and glued them down to a piece of foam core like the instructions said. I build a box around the pieces and sealed it with hot glue and modeling clay. I then mixed up my catalyst and silicon compound and stirred it like crazy. Once it was adequately mixed I poured it into the box over my glued down pieces.
Here is where my problems started. I only had enough silicon to go about halfway up my models. Great. I decided to solve this problem by making my mold box smaller. I couldn't take it apart so I added shims of foambaord into the box. I kept doing this until the silicon was about 3/4 over all the pieces. I then started sticking paintbrush handles in the dead space to try and displace more of the silicon.
I finally got enough stuff crammed into the mold box and tilted it just right so that all my pieces were covered. All I had to do now was wait. The box said it would take about 4 hours to set and 24 to fully cure.
The next morning before heading to work it was time to check out my handiwork. I started pulling the sides off of the box and everything was going good. I got good nice breaks and it felt like other silicon molds that I had dealt with before.
I pulled the mold off the bottom of the board and started to pull out my 'masters.' They wouldn't budge. Ok. I grabbed a hobby knife and started cutting away at some of the silicon that was holding them in place.
Long story short I ended up ruining my mold. The silicon that came with my kit was very firm. It didn't have much give to it. This kept my from being able to wiggle my pieces out. Instead of stretching the silicon would rip.
I also chose some bad models to try and make a mold of. The models had legs that were kind of spread. When I poured the silicon over the models it flowed around the legs but cased the model in. In order to cast something like this I would have had to make a two-piece mold.
I have not given up though! What pieces that I could make out looked like they did a very good job at capturing detail. I think I need to give it another go but start out smaller. I think that I will try sculpting a Space Marine shoulder pad and then try making a mold of that. I figure if I make it solid I won't have as many problems.
I learned quite a few things in this little endeavor so it wasn't a total loss. I will try this again sometime and I will let you know how it goes.