Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. Broadly, modern glass container factories are three-part operations: the batch house, the hot end, and the cold end. The batch house handles the raw materials; the hot end handles the manufacture proper—the forehearth, annealing ovens, and forming machines; and the cold end handles the product-inspection and packaging equipment. The following table lists common viscosity fixpoints, applicable to large-scale glass production and experimental glass melting in the laboratory: Batch processing is one of the initial steps of the glass-making process. The batch house simply houses the raw materials in large silos (fed by truck or railcar) and holds anywhere from 1–5 days of material. Some batch systems include material processing such as raw material screening/sieve, drying, or pre-heating (i.e. cullet). Whether automated or manual, the batch house measures, assembles, mixes, and delivers the glass raw material recipe (batch) via an array of chutes, conveyors, and scales to the furnace. The batch enters the furnace at the 'dog house' or 'batch charger'. Different glass types, colors, desired quality, raw material purity / availability, and furnace design will affect the batch recipe. The hot end of a glassworks is where the molten glass is formed into glass products, beginning when the batch is fed into the furnace at a slow, controlled rate by the batch processing system (batch house). The furnaces are natural gas- or fuel oil-fired, and operate at temperatures up to 1,575 °C (2,867 °F). The temperature is limited only by the quality of the furnace’s superstructure material and by the glass composition. Types of furnaces used in container glass making include 'end-port' (end-fired), 'side-port', and 'oxy-fuel'. Typically, furnace 'size' is classified by metric tons per day (MTPD) production capability. There are currently two primary methods of making glass containers: the blow & blow method for narrow-neck containers only, and the press & blow method used for jars and tapered narrow-neck containers .