Dextrin vs Native Starch for Paper Coating
SEVAGRAM EXCIPIENTS
On paper, both dextrin and native starch can act as a binder for surface sizing or coating. In practice, mills choose between them based on one variable more than any other: viscosity at usable solids concentration.
Viscosity Behaviour
Viscosity behaviour. Native starch becomes thick quickly as concentration rises, limiting how much can be applied before the coating mix becomes too viscous to run through standard equipment. Dextrin, because its molecular chains have already been partially broken down by roasting, stays workable at a much higher solids concentration, letting mills get more binder onto the sheet per pass.
Cost
Cost. Native starch is generally the lower-cost raw material, since it skips the roasting step entirely. Dextrin costs more to produce but can offset that with better coating efficiency and less water needing to be removed during drying, since a more concentrated solution carries less water per unit of binder applied.
Performance on the Sheet
Performance on the sheet. Dextrin tends to produce a smoother, more even surface film with fewer issues like dusting or picking during printing. Native starch can perform similarly in lower-demand applications, but mills running higher-speed, higher-quality print stock often find dextrin gives more consistent results.
When to Choose Which
When to choose which. For high-speed coating lines, premium print-grade paper, or carton board needing strong surface bond, dextrin is usually the better fit. For lower-cost or lower-demand applications where coating speed and surface finish are less critical, native starch can be a more economical choice.
Frequently Asked Questions
Can native starch be substituted for dextrin in a coating formulation?
Sometimes, but expect to run at lower solids concentration to keep viscosity workable, which can reduce coating efficiency compared to dextrin.
Is dextrin more expensive than native starch?
Generally yes, due to the additional roasting process, though this can be offset by improved coating efficiency and lower drying demand.
Does dextrin perform better on high-speed paper machines?
Often yes. Its lower viscosity at high solids concentration tends to suit high-speed coating and sizing applications better than native starch.