Application Surface
Aqueous starch deposition modifies the surface porosity and moisture absorption rate of paper substrates during the final stage of manufacturing. Starch spraying coats the web with a uniform layer of dissolved binder to improve ink holdout and mitigate fiber picking in offset printing. This operation requires precise control over nozzle pressure and liquid viscosity to prevent streaks or uneven saturation across the paper width.
High pressure settings drive the mixture into the sheet core to increase internal bond strength. Conversely low pressure settings restrict the substance to the outer fibers to maximize surface smoothness.
Deposit Mechanism
Nozzles mounted above the wire or after the size press distribute the solution in a controlled spray pattern. The mechanical atomization of the fluid creates microscopic droplets that land on the sheet surface before it enters the drying section. Thermal energy from the dryer drums then evaporates the water content to leave a solid starch film integrated with the paper fibers.
Operators adjust the spray volume based on the basis weight and the intended finish of the final product. Dense coverage reduces the permeability of the sheet to oil and water based inks alike.
Quality Threshold
Uniformity remains the primary constraint for a successful print substrate. Irregular distribution of the starch solution results in mottle where ink receptivity varies across the print area. Laboratory testing measures the Cobb value or ink transfer rate to confirm the efficacy of the application.
Consistent spray density ensures that the mechanical load on the paper surface stays stable throughout a long print run. Proper application of this additive increases the resistance of the sheet to surface abrasion during finishing processes.
