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How to choose among fountain-type gravure coating systems
Fountain gravure is a 2- or 3-roll stack: direct, reverse, or differential reverse. The blade and pan decide whether you get streaks, foam, or a cell pattern in the coat. Call 800-249-0337.
Gravure coaters are usually 2-roll or 3-roll stacks: direct, reverse, reverse-offset, differential reverse, and differential reverse-offset. This note stays on fountain-type systems (open pan), not enclosed chambers.
Direct gravure
The lower roll is tubular steel, engraved, chrome plated. It turns with the web at web speed. An overall engraving is chosen for the coat. The roll sits partly in a pan; a doctor blade wipes the lands, leaving the cell volume. Oscillate the blade so wear is even and debris does not lodge and streak.
The backup roll is an elastomer sleeve, web-driven or gear-driven. On thin, flexible webs, keep a rubber roll for each web width and undercut the ends so coat past the web edge does not offset onto the rubber. Nip is typically 50-100 lb per lineal inch, air or hydraulic. Once you pick the cylinder, the only way to change volume on that roll is to change percent solids.
Advantages: widely used; uniform coat; low-to-medium equipment cost.
Disadvantages: the engraving pattern can print through unless the coat levels; viscous coats are hard to doctor at speed; high-speed rotation can throw coat out of the pan; foam from agitation.
Warm the coat to cut viscosity so cells release and flow out. A polishing bar (highly polished tube on the coated face, with throw-off at stop, optionally driven and heated or chilled) only repositions the already-metered film. It is not a second doctor. A reverse-angle blade shears instead of squeegees; as viscosity rises, hydraulic force seats the blade tighter and fountain turbulence drops.
Reverse gravure
The engraved cylinder turns opposite the web. The wipe hides cell pattern and gives a smoother laydown, useful on aqueous and high-solids coats that do not flow out. Because the web is not tightly nipped, you can vary cylinder speed and therefore coat weight, which direct gravure cannot do on one roll.
You cannot press the etched and impression cylinders into a tension-control nip. Use a driven backup on thin film. High-tensile, flat webs can run on an idler yoke. Reverse wipe raises cylinder wear; coating and substrate abrasiveness matter. Relocating the doctor to the other side of an existing direct coater is not a small field job. A flooded-blade setup (dams on the cylinder, blade left in place) is the usual workaround.
Differential reverse lets you change etched-cylinder speed to match wrap, web path, and spacing. Layouts (direct/reverse, offset, 3-roll reverse pan-fed and nip-fed, kiss, metering rod, knife-over-roll) are in the original PDF.
Related Cattie grades
- #8159 — Heat-seal lidding hot melts for extrusion, gravure, or slot die. FDA 21 CFR 175.105.
- 8300 — Yogurt-lidding heat seal, a typical gravure coat.
- 8240 — Food-packaging heat seal, non-blocking.
- 8209 — Cohesive for candy-bar wrap; run on gravure or flexo.
Call 800-249-0337 or email sales@cattieadhesives.com.
General plant guidance only — not a substitute for your process, SDS/TDS, or line trials. Call 800-249-0337 to match a grade.