Cook 5 to 6 batches of printing varnish per shift.

A printing varnish is a cook and a dispersion in the same vessel. Resin has to go into the oil or solvent, the heat has to hold long enough to build body, and the batch has to come back down to a temperature you can discharge, adjust, and filter. A kettle that only stirs makes you wait on heat-up, wait on wet-out, and wait again while a slow agitator tries to even out a hot spot. The shift ends at four batches because the tank, not the formula, set the clock.

Kady International has listed this duty for years: cook 5 to 6 batches of printing varnish per shift. The KADY® mill pumps the cook through radial slots in a high-speed rotor and drives it into the staggered slots of a close-clearance stator, at tip speeds up to 9,000 feet per minute. Jacketed heat does the temperature work. Impact, attrition, and forced recirculation wet the resin, break gels and fisheyes, and turn the vessel over fast enough that the next charge is not still waiting on the last one.

Send the resin, the oil, and the batch size. Call 207.883.4141 or send a RFQ. We will match the head, jacket, and vessel to the cook instead of forcing the varnish onto a stock kettle.

Where the Shift Actually Goes

Five or six batches is a cycle-time claim. It only holds if each step that used to be serial can overlap.

• Heat-up. A jacketed vessel plus high circulation moves heat into the oil faster than a slow sweep on a large static surface.
• Resin wet-out. Hard resin, alkyd intermediates, and phenolic or maleic cooks fisheye if the liquid never reaches the particle. The head forces vehicle across the resin surface.
• Body and clarity. Undissolved resin and local gels show up later as dirt, seed, or a filter that blinds. Recirculation through the stator keeps the cook uniform while it is still hot.
• Cool-down and discharge. The same turnover that heated the batch pulls heat back out through the jacket, so the varnish is adjustable and pumpable before the shift is gone.
• Changeover. A shorter cycle only helps if the vessel can be emptied and cleaned without giving the next resin the last batch’s heel.

How the KADY Head Cooks a Varnish

The dispersion head is a slotted rotor inside a slotted stator. Upper and lower propellers feed the head so a viscous cook does not sit in a dead zone while a small volume overheats.

• Circulation is the heat-transfer surface. Product is forced through the working zone and back to the jacket wall, so temperature is not a skin on the vessel and a cold core in the middle.
• Resin solution, not a smear. Impact and attrition break lumps and gels that a propeller would tumble for the rest of the cook.
• One vessel for the cook and the finish. Many formulas dissolve, body, and homogenize without a transfer into a second mixer. That is where the extra batch in a shift comes from.
• Speed on a drive, not a fixed sheave. Variable-frequency control holds tip speed to the viscosity in the kettle, high while the resin is wetting, lower once the body is there.

The mill is built to mix, disperse, and cook. Printing varnishes sit in that overlap: heat-set, sheetfed, and overprint vehicles, alkyd and oleoresinous cooks, and the resin solutions that later get pigment. Kady has also noted that the same approach cuts varnish formula adjustment time to minutes once the cook is uniform enough to sample.

Run the cook on your resin, not a stock demo. Kady offers free testing. Call 207.883.4141 or start at free testing and bring the cut, the oil, and the temperature window.

What Has to Be Engineered In

• Jacketed vessel. Heat-up, hold, and cool-down on the same shell.
• Temperature indication. So the hold is a number, not a guess from the wall.
• Cooled shaft where the formula needs it. High tip speed and a long hold should not cook a bearing or scorch a film at the head.
• Sweep or auxiliary flow on heavy body. When viscosity climbs, the propellers and sweep keep the batch feeding the rotor.
• Closed cover. Solvent cooks and odor control do not belong on an open kettle.
• Alloy to the cook. Stainless is standard. Special alloys are available when the resin or the cleaning chemistry requires them.

From a Lab Cook to the Shift

The Model L uses the same rotor-stator principle as the production mills, so a resin cut found on the bench is meant to correlate to the kettle, not to a different mechanism. Production follows batch size and how many turns the shift has to make.

• Lab mills for resin cuts, body checks, and customer samples.
• Top entry mills for batch varnish cooks and formula changes.
• Bottom entry mills when discharge of a heavy cook or vessel geometry calls for it.
• High-speed production mills for full-scale cooking, dispersion, and homogenizing.
• Refurbished mills, rebuilt to factory specs and shipped with a new-machine warranty, when the cook is proven and the capital budget is not.

What to Have Ready Before You Call

• Resin type and form: solid, flake, or intermediate, and the oil or solvent it dissolves in.
• Cook temperature, hold time, and the body or viscosity you sample against.
• Batch size, batches per shift today, and what the kettle is waiting on.
• Solvent, odor, and cleaning limits.
• Whether the same vessel also disperses pigment or only cooks vehicle.

Put the Cook Through the Head

KADY® International has designed and built high-speed rotor-stator mills in Scarborough, Maine since 1949. The mills mix, disperse, cook, and homogenize fluid and solid systems, and they are running in more than forty countries.

Talk to sales and engineering about a varnish cook. Call 207.883.4141, or contact Kady. Ask for a lab trial if you want the resin run before you commit to a mill.