Paperboard Wet End Additive Sorption Mechanics and Chemical Retention Verification
Verify paperboard wet end additive retention using dynamic drainage jars and extraction GC-MS to ensure food contact compliance and prevent converting failures.
Britt Dynamic Drainage Jar
Laboratory Apparatus
Wet-end papermaking chemistry evaluation requires controlled agitation to simulate the turbulent conditions present on high-speed paper machine forming wires. The Britt dynamic drainage jar isolates chemical retention mechanisms from mechanical filtration forces by utilizing a perforated screen and an adjustable variable-speed impeller. Papermakers utilize this instrument to measure first-pass retention of fines, fillers, and functional additives under quantified shear conditions.
Hydrodynamic Testing
Standardized testing procedures introduce diluted paper stock into the jar above a screen sized to allow fines and fillers to pass while retaining longer wood fibres. Operating the Britt dynamic drainage jar involves setting specific agitation speeds to replicate machine turbulence, collecting filtrate through the bottom stopcock, and calculating the mass fraction of solids that pass through the screen. Additives such as cationic starches, microparticle systems, and synthetic retention aids are evaluated by comparing filtrate solids content before and after chemical dosing.
Varying impeller rotational speeds allows technicians to chart retention efficiency against fluid shear rates, revealing the shear resistance of chemical flocs under process conditions identical to machine headboxes and former shoes.
Retention Limit
Measurements obtained from this testing apparatus do not fully model mats formed under rapid vacuum dewatering on commercial paper machines. Thick fibre mat formation is explicitly prevented by the continuous mixing mechanism, meaning mechanical entrapment effects are excluded from the test result.