Benefits of Spray Starch for Paper & Board Mills
SEVAGRAM EXCIPIENTS
Most mills do not switch to spray-applied starch because it is novel — they switch because a specific problem keeps showing up on the production floor: weak top liners, dusting at the slitter, or a cross-machine strength profile that will not even out no matter how the wet end is adjusted. Spray starch tends to solve a narrow set of problems very well, which is why it has stayed a standard tool in paper and board mills for decades.
Key Benefits of Spray-Applied Starch
- Targeted strength placement — starch lands where it is sprayed, not diluted across the fiber mat, so the outer plies or top liner get a concentrated dose of strength exactly where converting and printing stress the sheet most.
- Cross-machine profile correction — spray bars can be zoned, letting operators increase or decrease application across the sheet width to flatten out a strength or moisture profile that a flooded nest size press cannot adjust on the fly.
- Lower capital cost than a size press rebuild — a spray bar is comparatively simple to retrofit onto an existing machine, which matters for mills that need a strength fix without a major capital project.
- Reduced dusting and improved printability — surface-applied starch binds loose fiber and filler at the top of the sheet, which converters notice as fewer dust-related print defects.
- Fewer board rejections — consistent surface strength reduces edge crush and burst strength failures that would otherwise show up as rejected board at the converting stage.
Spray Starch vs Wet-End Starch Addition
Wet-end addition is usually the cheaper option per kilogram of starch used, but a meaningful share of it never bonds to fiber and instead leaves the system in white water, which is both a cost loss and an effluent load increase. Spray-applied starch, by contrast, lands directly where it is needed, so mills typically see a better strength response per kilogram applied, even though the spray-grade starch itself may need more modification (lower viscosity, finer particle size) to perform well through nozzles.
In practice, many mills run both: a baseline wet-end addition for bulk strength, with spray application layered on top for targeted correction where the basic recipe falls short.
What to Look for in a Spray Starch Supplier
Spray systems are unforgiving of inconsistency. A starch batch that cooks out a little thicker than usual, or has a wider particle size distribution than the last delivery, shows up immediately as nozzle clogging or streaking on the sheet. When evaluating a supplier, mills typically look at:
- Batch-to-batch consistency in viscosity after cooking
- Particle size distribution and how cleanly it disperses in slurry
- Technical support for troubleshooting application issues on the machine
- Reliable supply continuity for mills running continuous production
Frequently Asked Questions
Does spray starch replace wet-end starch addition?
Not usually. Most mills use spray starch alongside wet-end addition, with spraying used for targeted correction rather than as the sole source of sheet strength.
Why does spray starch reduce board rejections?
Consistent surface strength reduces failures like edge crush and burst strength at the converting stage, which are common reasons board gets rejected before it reaches the customer.
Is spray starch more expensive than wet-end starch?
Per kilogram, spray-grade starch can cost more due to the modification needed for clean nozzle application, but mills often see better strength return per kilogram because less is lost to the white water system.