Wednesday, July 15, 2009

Sculpture 1: Lost Wax Casting

Bronze casting is quite fun, so far, and a little tricky. Basically you make a wax sculpture, make vents and such from wax, coat it in acidic something and sand, melt out the wax and kiln fire the shell hard, then melt bronze in a crucible and pour it into your mold. It is pretty much the easiest metal mold process ever, but it is still a bit tricky on your first go, even with an instructor and everything in the studio set up really well.

First you ladle out a bit of wax onto the shallow basin of water.
This basin is made from plaster.


Then when it has cooled but not entirely, you pull it out and dry it off, then mold it. We were permitted to use hot water, soldering guns, and I used also dipping it in the wax even though that wasn't suggested. Basically I have played with wax and bees wax and paraffin a number of times, but never such sticky wax or with so many tools.
This is the other form of the wax, which is used for gates, vents, and sprues (I do not know the difference really) as well as for internal armatures. My first go didn't have an armature and the wax had some water in it and was basically just a mess, but on the second try it worked a bit better.
Then you sketch your project on a tracking sheet. This lets the instructor map out where you need vents for the air to escape in order for the bronze to fill the item properly. We also use the sheet to track how the ceramic shell is coming along, since that step happens over several days.

So this is the vat of acid. You have to wear gloves and turn off the mixer and then you dip your item and its whole mold casing thing.

Then you roll your item in fine sand (for the first 2-3 coats of the shell- after that you use coarser sand for strength.). Actually rolling did not work for mine because the vent joins were very small and thus the connection points were thin and weak. So after I resoldered those I just sprinkled with the sand.
Here are some sculptures drying after being dipped and rolled. Mine is on the right. The other ones visible are multiple sculptures sharing one gate because they are quite small and it saves time and bronze.

2 comments:

Deepak Tigga said...

Hey great post man!!!! You have explained each and every things in a great way!!!! I have own website related to metal casting , sand castings and other casting process i.e. industrialmetalcastings.com

castech said...

Lost Wax Casting which is widely known as Lost Wax Investment Casting is one of the most effective casting process used in Metal casting.