The Global Leader In Viscosity For Over 75 Years
Brookfield AMETEK

Flexible Animal Glue/Book Binding

Process Viscometer Application Data Sheet


Brookfield's model AST-100 immersion-probe viscometer is ideal in controlling the viscosity of flexible animal glue used in the book binding process. There are two distinct known processes that our instrument has been used to measure and control the adhesive's viscosity. The two processes are the book cover process and the book binding process. Both applications operate similarly whereas they apply an adhesive onto a roll coater machine.

Problem Description

As the adhesive is applied onto the roll coater, the fluid's viscosity will change as they process it. This material, in a solid non-flowing form at room temperature, is applied at elevated temperatures, where the material is liquid. When the viscosity of the liquid is not measured and controlled, the quality of the adhesive directly affects the quality of the end product. When the viscosity is below the optimum level, less material is applied to the process, which will not cover the entire substrate and will not adhere as it is designed. When the viscosity of the adhesive is too high, the adhesive is excessive which will deposit too much material onto each substrate and also require more cleanup time as the excessive adhesive will be displaced onto the roll coater drum and other exposed surfaces.


The operation of applying adhesive onto the pages of the bookbindings or onto the book covers is typically accomplished on a roll coater. The adhesive is stored in an open (atmospheric pressure) vessel. It is then pumped over to the applicator, or roll coater with the unused adhesive returned to the vessel. As this adhesive is applied, the viscosity of the returned material will affect the entire reservoir. As the viscosity of this material increases, water can be added into the system to replenish the lost fluid. The addition of this water will bring the viscosity to within the control range to maintain a consistent product flowing out to the roll coater.

By installing the model AST-100 viscometer, the adhesive being applied to the paper can be continuously monitored and controlled by adjusting the water additions while the viscosity of the adhesive increases. The proper control of this installation will result in savings from less adhesive applied, less end product waste, reduced cleanup time, increase in product produced, and controlled quality of the product.


The model AST-100 viscometer should be mounted directly into the glue's reservoir. The requirements of the viscometer is to immerse the bottom 4 inches of the probe into the adhesive, measuring homogeneous solution, and under laminar (non-turbulent) mixing conditions.

The support collar that we provide can mount the viscometer. The support collar is designed so that it clamps down on the outer sleeve of the viscometer to obtain the correct immersion length into the fluid. Loosening the collar and clamping the outer sleeve at varying levels may vary the insertion. This support collar should be tack-welded into place on only half of the collar so as to maintain the clamping function.

The maximum immersion of the probe into the solution is limited to approximately 6 or 8 inches below the head of the viscometer. This area is where the rotating lip seal sits onto the rotating shaft and is not meant to be full of process liquid. When fluid enters this region it will surpass the rotating seal and enter into the bearing housing with adverse effects on the rotating shaft.

The installation is typically within atmospheric vessels, at elevated temperatures up to 140-150 F. The temperature is maintained by the use of heating coils. The agitation within this reservoir must be maintained at a low rate in order to fold over the material but to not introduce air trapped within the fluid.

The water addition solenoid valve should be located as close to the reservoir as possible. Therefore, the shut-off of the valve will be immediate and not introduce too much excess water due to drainage from the valve to the reservoir.


  • Automates viscosity control, which directly relates to amount of adhesive applied (coating thickness)
  • Less waste produced
  • Quicker cleanup times
  • Increase in production
  • Less adhesives applied, with cost savings of this raw material

Return On Investment

The use of Brookfield's model AST-100 viscometer typically provides a payback of instrument cost and installation within 6 months to one year.