Pint can of BCS Heat Set Core Oil
A core is used to make hollow spaces in metal castings. After the main pattern has been rammed up in the sand mold and pulled, a core can be placed in the cavity to create a void in the casting.
An example of a common feature created with a core is the bore of a cannon. The pattern for the cannon is first molded in sand. After the pattern is removed, a hard sand core is then placed in the cavity to create the bore of the cannon. The core prevents the molten metal from completely filling the space. After the metal hardens the casting is pulled from the foundry sand. The core sand is then removed from the inside of the casting to reveal the bore of the cannon.
BCS The core oil is mixed with sand to form the core sand. The recommended mixture is 1 Ounce by Weight of oil to 20 Ounces by Weight of the foundry sand. It may be necessary to spray the sand with clean water if it becomes too dry to hold its shape when making the core. The water should only be added after the oil is mixed with the sand.
It is important to carefully weigh the items. A good kitchen type digital scale or digital postal scale is required for best results.
Mixing can be done by hand for small quantities (1 Oz oil with 20 Oz Sand). The sand and oil must be very throughly mixed to be sure that all the sand is covered with the oil. I have used a hand held electric kitchen mixer with good results and it is a lot easier than manual mixing.
A typical cylinderical core is made as follows:
This core sand can only be used once as a core sand. After shake out the sand can be mixed in with Budget Blend water bonded molding sand, or discarded.
The mixed oil and sand has a limited shelf life. It is recommended that only the amount needed be mixed and used in the same day.