When you hear the word inkroom, do you cringe and suddenly have visions of ink-splattered cans crammed onto shelves from floor to ceiling and colorful globs dripping down the shelves and onto the floor? Rarely do screen printers pay as much attention to their ink areas as they do the prepress, production, or finishing departments in their companies. But a clean, organized, and efficiently operated inkroom is just as critical to production consistency and high-quality printing.
Current technology can help you automate your inkroom to match the pace of your prepress and production areas and promote a highly efficient workflow throughout your operation. This article explores essential tools you’ll need for ink storage, dispensing, measuring, and mixing. For in-depth coverage of ink-management software, refer to the article, “Bring Order to Your Inkroom with Ink-Management Software,” in the Oct. 2004 issue of Screen Printing magazine.
Before we dive into the various types of ink-management tools and equipment available to you, it’s important to note that the type of ink you use is a key factor in determining the type of equipment you’ll need to purchase. Whether you use plastisol, water-based, UV-curable, solvent-based, or specialized inks—in ready for use (RFU) form or as pigment and base mixing system—the varying properties of the inks will influence which equipment is best suited to your applications.
Storing the ink
Let’s begin with the basics. Your inkroom should be stocked with plenty of buckets, spatulas, scoops, stir sticks, and plastic or metal cups. You can find these tools at a local hardware store or through a supplier of screen-printing products. Stainless-steel spatulas and scoops are recommended, as wooden tools can leave splinters in the ink, causing image defects and wreaking havoc when the job goes to press. Cups can be purchased at a grocery store, but you’ll need to make sure the cups do not have a wax coating, as the wax may contaminate the ink during stirring.
Containers come in a variety of styles and sizes. Ideally, you should have several 1- and 5-gal containers for mixing custom colors. Pint-size containers can be used for storing a control batch for each batch mix. Screen printers typically purchase ink in containers that range in size from 1-55 gal. Some manufacturers offer totes, which hold up to 300 gal of ink. Totes are usually pressurized and equipped with a tap in the bottom that allows users to dispense the ink into smaller containers.
Pumping the ink
Pumps are available to remove ink from the container prior to mixing. Pumps are usually required when working with large containers or drums of ink. However, some manufacturers offer pumps for use with containers as small as 1 and 5 gal. The type of pump you use will depend on the ink’s viscosity and pigmentparticle size. Your ink supplier will be able to furnish this information.
Piston and air-operated double-diaphragm pumps are two of the more prominent types used in our industry. Basically, a piston pump is a metal cylinder with a piston inside that raises and lowers under air pressure, bringing ink up into the cylinder. As the piston moves downward, it pushes the ink out through a valve. The process does involve a considerable amount of friction; therefore, it is not suitable for certain types of ink, such as UV-curable formulations, where a friction cure may result. However, piston pumps are suitable for high-viscosity inks, such as plastisols.
Air-operated double-diaphragm pumps are less expensive than piston pumps, do not generate friction, and are designed for low-viscosity, freeflowing inks, such as UV-curables.
Double-diaphragm pumps are displacement pumps that compress fluid by decreasing the volume of a chamber that contains the fluid. Two diaphragms are oscillated (mechanically, hydraulically, or pneumatically) to displace the fluid. A chamber is divided with one side using hydraulic fluid, air, or a motorized drive to move the diaphragm. The fluid is pulsed through the pump.
Some pumps are available to fit a particular ink manufacturers’ ink containers, such as the Amergraph Spindex pumps for 1- and 5-gal containers. The pumps come with a latching system designed to secure the pump lid to the ink container, as well as a silicone rubber follower, an adjustable pump lever, a 16-in. flex tube, and the Spindex nozzle. The pumps are designed to dispense plastisols within a viscosity range of 100,000-300,000 cps to an accuracy of ±0.1 g, with no drip. Users can control the pressure and volume through the adjustable pump lever, and the flex tube allows users to place the nozzle exactly where it is needed.
An important consideration in using pumps is pump-pressure ratio. You can contact your ink manufacturer to find out the pump-pressure ratio you require.
Dickson Dorrier, vice president of Southeastern Process Equipment & Controls, Inc. (SPEC), says diaphragm pumps are typically 1:1 or 1:2 ratio pumps; whereas gear pumps deliver higher ratios, and piston pumps deliver even higher ratios. For example, if you put 100 psi of air pressure into a piston pump, you might get up to 4000 psi of delivery pressure out, which is ideal when working with thick inks.
Dispensing and measuring ink
A dispensing system is a necessity if you do color matching or mix pigments and bases. If you don’t want to employ the prehistoric method of measuring the amount of ink you’ll need by hand, an automated dispensing system should be a permanent fixture in your shop. Another crucial piece of equipment is a digital scale, such as the one shown in Figure 1,
which is offered by Amergraph. Many automatic dispensing systems come with scales, but if you measure and dispense your inks by hand or use a custom mixing system, consult your ink distributor for recommendations for a digital scale.
Mettler scales are commonly used with ink-dispensing systems, such as Novaflow Systems’ family of dispensing equipment. Mettler scales are available in a variety of models, support ink capacities from 75-6000 lbs, and offer weighing accuracy from ±0.0002 to ±0.1 lb, depending on the scale.
Dan McKenney, vice president North American sales for Novaflow, says, “We design the hardware with several things in mind, including weighscale accuracy and product viscosity. Typically, when designing a dispensing system for UV screen and conventional screen-printing inks, we select a highaccuracy scale (the smaller the batch size, the higher the precision of the scale). In regards to product viscosity, UV screen and conventional screen products, due to their make up, require a careful examination to ensure we size the fluid circuit properly.”
Other ink-weighing products may be combined in a package that includes a scale, computer, and software. The system shown in Figure 2
is the Integrated PC Balance Blending System from Sun Chemical Corp., which is designed for small operations that do a few blends per day. The user places a container on top of the scale, selects a recipe to blend, and then manually weighs it. When zero has been reached in weighing the first ingredient, the user then moves on to the next ingredient, weighs down to zero again, and repeats this process for the remaining ingredients.
Rutland Plastic Technologies offers Advantage ink-dispensing scales with its M2007 Ink Mixing software. Users calculate a batch size, and one button displays the on-screen interface for the scale. The first formula is displayed, and the first ingredient is ready to weigh. An Overweigh button recalculates the remainder of the recipe to compensate for any overages. Three scales are offered and have capacities that include 1200 g (with ±0.01-g resolution), 6000 g (with ±0.1-g resolution), and 30 kg (with ±0.5-g resolution).
The scale interface is automatically loaded with M2007 Ink Mixing Software, featuring ink-usage estimates with stencil-thickness adjustments, recycle functions, reporting functions and formulation printing, capability to e-mail formulas and reports, and Rutland ink-mixing systems. Rutland’s M2 and CB inks are specified to work in a variety of manual and automatic ink-dispensing systems from several manufacturers, including Vale-Tech, Amergraph, and BEK Equipment.
Ink-dispensing systems typically fall under two major types: volumetric and gravimetric. With volumetric systems, operators use meters to determine a certain volume of product. The advantages to using a volumetric-based system are the relatively inexpensive cost and the capability to dispense all of the components of a formulation at once, allowing for a quicker response. With gravimetric systems, operators weigh each ingredient as they use it. Gravimetric dispensing is a very definitive process, with a high degree of accuracy, which makes it a more popular choice among screen printers for dispensing inks.
Some dispensing systems are customizable or built to suit, such as those from Novaflow Systems (Figure 3).
The ink-storage container, pumps, and hoses are sized to fit the customer’s products. All of the systems are equipped with pneumatically controlled air pumps and air-actuated valves. Novaflow offers several different types of dispense valves, depending on the client’s requirements. This is all decided as part of the project-review process.
Like many dispensing systems, the Novaflow machines are equipped with a software program that also allows users to manage ink inventories. Through Novaflow’s Materials Management Software, users can monitor the performance of the system, create details on batch histories, view information such as job histories and inventory control by supplier, and retrieve reports on inventory variances.
To use the system, operators log on and select one of two ways to produce a batch of ink. Through the production schedule mode, operators can import a production schedule, select a specified ink on the schedule, confirm the weight, and start the routine, after which the software will instruct the operator to place a pail on the scale. The software recognizes the weight change caused by the empty container and begins dispensing. The second option allows operators to make an on-demand formulation based on a request. The operator selects a specific color, selects total weight, enters item code/job number, confirms weight, and the dispensing sequence begins as described in the first option.
Both of these options offer an automated work-off function, whereby the software will stop the operator from making new ink when a work-off option exists. The work-off function retrieves a list of every ink color in a customer’s inventory. The operator selects an item, and the software performs mathematic calculations based on the actual batch record for that specific ink batch when it was produced. The software then instructs the operator to find the container and place it on the scales, and then the system proceeds to dispense the required amount of new color base to convert the work-off to the desired color.
Operators also can export formulas from a spectrophotometer to the dispensing system, which then coverts the information to 100 parts and sends the formulation to the dispenser. The operator takes it from there, repeating the steps listed above.
Some manufacturers offer queuing systems to be used with their dispensing systems. Sun Chemical’s Q Master and Compact Q (Figure 4)
are designed for use with IDS dispensing systems, manufactured by Vale-Tech Ltd. and offered by several distributors, including Sun Chemical. The Q Master handles ink containers ranging in sizes from quarts to 1 gal. The system is fitted with up to 10 shelves and features an X-Y motor with a fork that rises up to a shelf, picks up the empty container of ink, and brings it to the dispensing device. The dispenser then reads the barcode attached to the ink container, which includes information such as ink color, quantity, date, and the formulation, and then dispenses the appropriate formulation. After dispensing, the Q Master places the container back on the shelf and retrieves the next container. The Compact Q accommodates up to 12 colors and is built for one container size.
Both queuing systems work with the Vale-Tech IDS dispensing systems (Figure 5).
The IDS10 holds 2.5 gal of ink in each vessel, the IDS25 holds 6 gal of ink in each vessel, and the LV allows users to dispense from 55-gal drums. Steven Presutto, Sun Chemical’s manager of technical information and training, explains that with the IDS10 and IDS25 systems, air pressure forces ink to the valve, and the valve opens and closes when it is instructed to by the software. A trolley, or balance on a motor, carrying the ink container moves to the appropriate valve, and the valves open and close through pneumatic controls to dispense a precise amount of ink as it is weighed on system’s scale. The IDS LV uses pumps instead of air pressure to deliver ink to the valves.
David Holmes, sales director for Vale-Tech says there is a common misconception that the IDS10 system is only suitable for larger printers. He goes on to say that with advances in computer and control system technology, it is now economically viable to install such systems for use by small- to medium-sized businesses. In fact, it is now feasible for any operation where blending and dispensing is required on a just-in-time basis. Ink-dispensing systems afford screen printers a high degree of flexibility in production planning and offer a faster, more flexible service to customers and with an enhanced color range.
Vale-Tech’s LV model uses a pump to support the removal of large amounts of ink from the large vessel. This system actually uses the same valve system, hoses, and trolley as the IDS models, but the ink-delivery system differs.
The dispensers can be built with 12-24 vessels, depending on the number of base colors that the customers needs to use. With 24 vessels, customers can use two separate ink systems when one ink system includes nine base colors, black, white, and clear.
The IDS and LV systems use Sun Chemicals’ Ink Manager software. It allows users to keep track of recipes and color blends as the operator formulates them, keep track of inventory, set minimums, and generate reports when certain inks are running low. An estimation feature helps users calculate how much ink they’ll need for a job. The rework function allows users to use excess ink that has been entered into the system. The software does require some user input, such as the size of the print, percent coverage of a certain color, number of impressions, which screen mesh will be used, and whether the job is singleor double-sided. The software considers these factors and uses the ink mileage that would be input into the system during setup and then calculates how much ink the user will need for a specific job. The software also can calculate the cost for that particular ink.
Presutto says that several factors should be taken into account when considering the purchase of an automatic dispensing system. Those factors include number of blends you typically mix per day, typical blend sizes, and space requirements of your facility.
“The real benefit to screen printers of moving into an automatic dispensing system is reducing the amount of excess ink you have on your shelves. We train our customers to make less ink than they think they need,” he says. “Dispensing systems, when used properly, allow you to make ink on demand. You don’t want to make more ink than you need and let it sit on the shelf for six months.”
SPEC offers dispensing systems for a variety of end users and ink manufacturers. For example, the company couples its 2000EV and RTL2000 dispensers (Figure 6)
with Nazdar’s ColorStar color-management system. ColorStar is available in several versions, including ColorStar Pro 2.0, ColorStar Manager, and ColorStar CheckWeigh. The version you choose depends on batch size and the software functions and features that you require for color management.
With the Pro 2.0 version, customers can use the software on their own computer and utilize features such as an enhanced calculation field for quantity- usage predictions, storage of print parameters for each formula, selection of UV ink lines with 360 Series inks and new PANTONE formulas, and creation of a database of custom colors. ColorStar Manager is equipped with all of the features of 2.0, in addition to an inventorycontrol field, inventory-status reports, inventory work-off functions, calculation of inventory-cost updates, productionmanagement reporting, and open architecture, which allows entry of any ink series or importing of custom formulas.
The CheckWeigh version includes ColorStar Manager, a desktop PC, laser printer (black and white), and lab scales for weights up to 4100, 8100, and 35000 g or production scales that support weights of 20 or 50 lb, depending on customer requirements. Other capabilities include scaling accuracy, automatic overpour correction, automated systems integration, lab-scale interface, ink-ratio calculation, Pantone color matching, quantity and usage predictions, job costing, storage of print parameters, and inventory tracking.
SPEC’s RTL2000 is designed for small batches: quarts, pints, or smaller containers. The system’s ink-supply tanks are arranged in a carousel configuration inside the machine. The carousel rotates to bring the ink ingredients to the dispensing point and then dispenses the ingredients into the containers. The machine then rotates to the next ingredient and dispenses that one at the same dispense point. Basic functions of the RTL2000 include a dispense-control computer that handles formula storage and dispensing controls, a dispense-control unit that houses the PC and necessary electronic and pneumatic control components, a digital scale, and 12-14 dispense containers.
The 2000EV system is designed for larger batches, typically 1- to 5-gal buckets, and includes the same inkmanagement features of the RTL2000. But is equipped with 10-20 multi-stage, pneumatically operated, piston-type dispense valves, in addition to 10-20 supply pumps, a pump stand with integral supply and return hose trough, recirculation capability, and a dispense-head washer.
Dorrier says two main considerations in purchasing an automated inkdispensing system are batch-to-batch shade repeatability and lowering cost. “You lower labor costs by having the machine do the dispensing for you, and you lower inventory cost by having the machine prompt you to use returned ink inventory. That tends to be a big area of payback—a large inventory that you can reduce,” he explains. “A lot of our customers use the dispensing system as a sales tool. They can tell their clients that they use an automated, computercontrolled dispensing system that guarantees the repeatability of the color, and if they print a job today, and print it again one month from now, the colors will be consistent.”
Wilflex’s DM4 DispenseMaster (Figure 7)
is designed for mid-sized to large shops that do a considerable amount of color matches for plastisol inks or want to closely manage their ink inventories. The system operates on Wilflex IMS color-matching software and allows users to call up a custom color in the database or select a Pantone formula and enter in the quantity of ink to be mixed. The bucket or container sits on a scale while dispensing occurs, and the weights of each component are monitored and controlled in real time by the software. The ink containers located on the side of the machine are equipped with pumps that move the ink from the individual ink containers through the pump lines and down through the nozzles located in the center of the system. There are three dispense modes, including gross fill mode (for high volumes of ink), fast fill mode, and fine fill mode (for smaller volumes of ink).
Wilflex also offers the dispensing system in an MX version for use with finished inks, as well as a base and pigment system. With the base-and-pigment system, base ink is pumped in from a 55-gal drum. The pigments are usually pumped from 5-gal containers. The dispensing system also is offered in an Equalizer version for base and colorants.
Dean Searles, Wilflex’s marketing manager, says that one aspect of automated dispensing systems that customers find appealing is that the use of such systems keeps the ink-mixing area very clean. Additionally, customers can make only what they actually need in ink batches, avoiding the costly problem of extra, unused inventory in their inkrooms.
Mixing it up
Ink-mixing equipment comes in many flavors, but in the screen-printing industry, the types of mixers you’ll most commonly find include variable-speed paddle mixers, high-speed dispersers, and closed-lid centrifuge mixers. The variable-speed paddle mixer consists of a platform with a paddle in the center. Users place an ink container on the platform, and the platform rotates, spinning the ink container. Paddle mixers do not generate a lot of heat or friction, thanks to the rotating motion, which makes them ideal for plastisol or high-viscosity inks, where heat sensitivity is an issue.
A high-speed disperser is essentially an electric motor equipped with a metal blade and controlled by a variable-speed rheostat. As the user increases the speed, the blade spins faster. This type of mixer can be used with most screen-printing inks; however, you need to be cautious of the amount of time that you mix the inks, as this type of mixer does generate heat.
With a closed-lid centrifuge mixer, you put air into the ink container, secure the lid on the container, place the container onto the mixer, and the mixer spins at a very high speed to disperse the ink. One advantage to this type of system is that its lack of blades or parts eliminates the need to clean the system. The closed-lid centrifuge mixer typically is used with low-viscosity inks.
The viscosity of the inks you plan to use is the key factor to consider when selecting an ink mixer. Presutto says that ready-for-use inks are, in most cases, relatively thin in viscosity (UV or solventbased), making them suitable for use with any of the mixers described above. However, screen printers need to be cautious when working with metallic blends, fluorescents, and other specialty inks.
“When you work with anything other than finished ink, you must mix the product well, because you are actually dispersing dry pigments at that point. You must generate proper vortex and mixing speed to disperse the inks,” Presutto says.
AWT’s Tornado ink mixer (Figure 8)
is a system designed for small batches or short runs. The Tornado is a turntable with reversible direction and variable speed. Users place an ink container on the turntable, lock it in, and the container—not the blade—spins. Adjustable speed (up to 45 rpm), adjustable height, varying sizes of blades, and container grippers are a few of the Tornado’s features.
M&R’s Turnabout (Figure 9)
is a self-centering mixer that rotates the ink container with a lifting and rolling action, which allows the mixer to reach ink that might settle on the sides and bottom of the container. The Turnabout can accommodate containers from 1-5 gal and is designed for use with thick inks and coatings, while M&R’s Turnabout HD is specifically designed to handle high-density formulations in 5-gal capacities.
Several manufacturers offer inkmixing systems for a more automated process. AWT’s Press Mate uses 50 lbs of compressed air to feed the ink directly to the press from the canister through feed tubes. Users place ink in a pressurized canister, which seals the ink inside, place feed tubes directly into the ink, seal the canister, and the ink is automatically fed to the press. Ink flow is controlled by an adjustable valve.
Become an ink impresario
There are many options available in inkmanagement systems that can help you regain control of your inkroom and all of the processes and procedures connected to it. Whether you choose a manual or an automated system, make sure the system you select will fully serve your shop’s needs and capabilities, today, as well as in the future. By doing so, you’ll be well on your way to an inkroom that you won’t dread entering and won’t have to hide from your clients.
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