Monday, April 2, 2012

First Casts

So as I mentioned on saturday my molds arrived from hirst arts, so sunday morning I made a run down to home depot. I was looking for the 25lb bag of plaster of paris that I saw online but no dice on finding it. Instead I saw a 25lb bag of joint compound that was supposed to be quickset. For 8 bucks I figured what the hell I'll give it a go and see how it turns out.

Now I get home and immediately realize it is going to be way too messy trying to work with this stuff out of the bag. So I find myself an old plastic trash can that is about 8 gallons maybe less, clean it out and dump the bag of joint compound in that. Next I run downstairs and get a stack of plastic china cups (about 8oz cups) and a couple plastic forks for stirring. I also found an old carboard box and cut out a large chunk of it to put over the desk to protect the surface. I should probably put plastic down on the floor too but didn't...

Reading online I found some tips and tricks on how to do the casting. The hirst site recomends that you soak the molds in a combination of jet dry and water before each cast. This acts as a mold release. I didn't have any jet dry available however and since a mold release is not required for casting with plaster I just went right along. I rinsed out the molds and set them on my table then I half filled up a china cup with water. Grabbed a scoop of the plaster with another china cup and slowly added it to the water. I went for about a 1 to 1 ratio of plaster to water. This seemed to produce good results. I mixed the plaster gently so as to reduce generating air pockets.

Note: Air pockets are evil!!! They happened a lot... Nothing was more annoying then finding a big old air pocket right in a piece of detail that you couldn't easily hide...

I gentley poored the mixture into the molds and allow it to overflow. I then pounded the table to attempt to get out some air bubbles. Now for the waiting... I need to wait 5-10 minutes before I do a scrape of the excess on top. Once that is done it will be another 10-15 minutes before the plaster sets enough to be popped out of the mold. Now it is on to the fun part, popping the pieces out and seeing what I got. The first few bricks pop out fine and I notice a few small air pockets but nothing major. Now to pop out the trim faces... crack... the little ledge on top breaks off. Son of a... ohh well it is my first cast problems are too be expected (It ended up being the norm I only had a couple that did not break). I set the pieces to the side, clean out the molds and start my second cast.

I tried using the same china cup but the left over plaster just made it hard to mix properly. Never the less the pieces popped out without much problems. You are supposed to let the bricks dry overnight before using them but I am much to excited to start building for that. So after I start my 3rd cast I go to the hirst website and pull up the Wizard tower plans and start building. I get a little ways into the project and decide that I don't need the plans I will just wing it. I also decided to make my own little octogan tower.

I did about 16 casts for the day and overall was very happy with the molds. I will note that it is important to let them sit overnight to fully dry. There are pieces that got a little big and they cause pieces to not go together as smoothly as they should. Trying to sand them down with a file to clean them up is simply not an option until they get nice and hard, they end up getting smooshy and crumble a bit.

I am going to wait until I make a good version of the towers before writing a post on them! In the end though I learned some lessons.

1) Let the darn things dry before using them
2) Mold release will help
3) A vibration table is necessiary
4) I need more molds to cast at once!!!

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