Methods of and systems for controlling dosing of drainage aid and optionally defoamer to brown stock of a brown stock washing process are provided. Certain embodiments of the invention provide independent control of drainage aid and/or defoamer to brown stock, which tends to provide improved efficiency in dosing each of the drainage aid and the defoamer.

Methods of and systems for controlling dosing of drainage aid and optionally defoamer to brown stock of a brown stock washing process are provided. Certain embodiments of the invention provide independent control of drainage aid and/or defoamer to brown stock, which tends to provide improved efficiency in dosing each of the drainage aid and the defoamer.

This invention relates to a method for manufacturing a sheet of paper or cardboard, comprising the addition of a water-soluble polymer P with a weight-average molecular weight greater than 750,000 Dalton to a fibrous suspension. This method comprises the following successive steps: preparing an aqueous solution A containing at least one water-soluble polymer P at a concentration C of between 0.1 and 0.5% by weight, said polymer P having a factor F(C) strictly greater than 4, with F.sub.(C)=600/C, 600 being the slope to reach 90% of the viscosity developed by aqueous solution A at 600 seconds at 25 C., obtained from the viscosity curve of aqueous solution A as a function of time, at the given concentration C, at 25 C., adding aqueous solution A to the fibrous suspension, at one or more injection points, forming a sheet of paper or cardboard.

This invention relates to a method for manufacturing a sheet of paper or cardboard, comprising the addition of a water-soluble polymer P with a weight-average molecular weight greater than 750,000 Dalton to a fibrous suspension. This method comprises the following successive steps: preparing an aqueous solution A containing at least one water-soluble polymer P at a concentration C of between 0.1 and 0.5% by weight, said polymer P having a factor F(C) strictly greater than 4, with F.sub.(C)=600/C, 600 being the slope to reach 90% of the viscosity developed by aqueous solution A at 600 seconds at 25 C., obtained from the viscosity curve of aqueous solution A as a function of time, at the given concentration C, at 25 C., adding aqueous solution A to the fibrous suspension, at one or more injection points, forming a sheet of paper or cardboard.