USG Casting Fireplace Surrounds - Manual (Page 17)

It is extremely important to design your shop so that the production
process flows smoothly. By ensuring that each step of the process
operates without delays and bottlenecks, and that one step flows into
the next efficiently, you will maximize production, maintain high
quality, and keep costs as low as possible.
Your shop should include the following departments that flow smoothly from one to another:
– Raw material storage
– Mixing/processing area
– Casting area
– Cleaning/trimming area
– Drying room
– Finishing area
– Storage/packaging area
– Shipping
Incoming Raw Materials You will need a place to receive and store raw materials, including gypsum cements, mold-making materials,
buckets, water hoses, and other items like lumber. Keep this area and the entire shop, if possible, at optimal room
temperature of 65°– 80° F, since the raw materials perform best within this range.
Mixing Successful mixing of gypsum cements requires following exact procedures. USG manufactures gypsum cements
that have very specific formulations, and shop practices must be standardized to gain the full benefits of the products.
You must follow the same procedures every time you mix. Any variation may result in poor product performance.
Use potable water source for mixing gypsum cements. Dirty water is never recommended, since impurities
affect setting times and can cause mineral deposits on the surface of the finished parts. Constant water tempera-
ture is also recommended to achieve uniform, high-quality results. Sift plaster into the water and soak to allow
replacement of the air surrounding the plaster particles with water. Use an accurate scale that includes a “tare”
feature for weighing, clean buckets (which must be kept clean for re-use as mixing or water-holding buckets),
waste containers (30-50 gallon plastic drums), and mechanical mixing equipment. Refer to USG publication IG503
and your USG representative for details on proper mixing procedures and the types of proper mixing equipment.
Process Flow
17 Casting Fireplace Surrounds