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Reclaim Your Screens to Maximize Your Profits
Part 1: Supplies and Equipment
Printing undoubtedly produces the greatest amount of wear and tear on a screen, but the reclaiming process comes in a close second. During reclaiming the mesh in a screen is attacked with harsh chemicals and high-pressure sprays, a lot of abuse for fragile threads only a few microns thick.
Many screens fall victim to ill-advised attempts to cut corners, such as using off-the-shelf products from the local home improvement store rather than chemicals specifically designed for reclaiming screens. Another example of false economy is the failure to buy proper equipment. A reliable pressure washer with an output of at least 1200 PSI is the one piece of equipment you absolutely cannot do without. Still, people will try anything to avoid buying one, including bundling up their screens and hauling them off to the local car wash.
Cutting corners in screen reclaiming often ends up costing you more in shortened lifespans for your screens and increased labor costs because they simply take longer to do the job. So to save yourself money and get your screens safely through the reclaiming process your first step is to make sure you have what you need to do the job, or rather jobs at hand.
Let's take a look at what is involved in screen reclaiming. It really breaks down into three separate tasks:
The equipment for job number one is about as simple as screenprinting equipment gets. You need something to lift the greater portion of the leftover ink out of the screen. The one essential requirement is that it has edges that won't damage the mesh. Screenprinters have used palette knives, paddle-like spreaders from restaurant supply houses, credit card-sized squares of plastic, or the plastic squeegees used to apply cut-vinyl sign material.
If a screen is to be kept in inventory against future reprints, the clean-up process would be much more involved. With a screen headed for reclaiming, you don't need to worry about removing all of the ink. In any event, clean-up of the screen should begin as soon as possible after the last print has been pulled. The longer you put it off, the harder it's going to be. This is especially true of air-dry inks. If reclaiming is going to be postponed you need to clean all the ink from the screen just as if it were going into inventory.
Now let's take a look at the supplies and equipment you need for the rest of the reclaiming process.
Equipment and Supplies for Reclaiming Screens
1. Reliable water supply and drainage.
This is a good reason for purchasing reclaiming chemicals from a regular industry supplier. But across this country many different state and local environmental rules affect wastewater disposal, so you really need to know what the regulations are in your area. Some localities may require special methods of dealing with the contaminated wastewater issuing from your tank. In others, you may be required to have a closed system to isolate and recycle your wastewater. A closed system or some sort of filtering system may be a necessity if you are on a septic system; some reclaiming chemicals can damage or block it.
Since your pressure washer will be used indoors, you need an electrically powered type. As far as amperage is concerned: the higher the better. As a minimum you need a pressure washer capable of delivering at least 1200 PSI. Studies suggest that screens can endure pressures up to 4000 PSI without sustaining damage.
Pressure washers come in both hot and cold water types. The cold water types are cheaper and generally better for reclaiming purposes. Manufacturers often supply figures for water flow in gallons per minute (GPM) and, sometimes, cleaning units (CU) (pressure multiplied by water flow), but PSI remains the most useful figure for comparing pressures washers to be used for reclaiming. Make sure that the unit has an adjustable nozzle. The ability to direct a tight spray at a stubborn bit of stencil clinging to the mesh comes in very handy.
That backspray, unless you have some means of controlling it, can travel quite a distance in your shop. The ideal means of controlling is a wash tank, also called a wash sink or a washout booth, essentially a shallow box resting on one of its narrow sides. One of its wide sides is open except for a raised lip extending a foot or more up from the bottom. The bottom of the tank generally slopes in the direction of the drain, and it should be wide enough to allow screens to be leaned against the back wall. If a screen isn't securely placed when you hit it with the pressure spray the powerful blast of water can send it flying. The drain opening should be protected with a strainer to block bits of debris that could clog your sewer. And if you're located in an area where environmental regulations require it, the drain should be hooked up to a waste processing system.
Wash tanks are made of galvanized or stainless steel or chemically resistant polypropylene. One of the most useful features manufacturers have come up with is a backlit panel that forms the back wall of the tank. This allows you to view the mesh against a light source, making it easy to spot blocked or damaged areas. It is equally useful for reclaiming and for washing out stencils after exposure. Most wash tanks serve this double purpose.
Donít scrimp on size when buying a wash tank. You may someday be printing with larger screens and it's easier and more economical to buy a larger one in the first place than to have to upgrade later. It should be placed in the shop away from anything that could be damaged by backspray, especially screens ready to go onto the press or to be kept in inventory with the stencil intact.
When you are buying protective gear, buy heavy-duty equipment. It not only protects you better, but lasts longer. For example, when buying rubber gloves invest in industrial-strength types, not the kind designed for household use. Some printers also use facemasks with air filtration. When a pressure-washer blasts dehazer out of a screen itís easy for the air surrounding the wash tank to become saturated with a mist containing caustic chemicals, which is very unpleasant to breathe.
The third chemical is dehazer. This is usually a caustic material, which is, fortunately, not required every time you reclaim a screen.
The dehazerís job is to remove ghost images, stains and telltale outlines of former print jobs formed by tiny fragments of ink embedded in the weave of the mesh. The mesh openings may be clear but these faint outlines remain. Depending on the fineness of the mesh and the kind of detail required in your next print job, ghost images can be ignored until they build up to a point where they begin to interfere with the process of exposing a new stencil. That's when you need to haul out the heavy artillery, your dehazer. This is the one you want to be careful of. Many of the popular dehazers on the market are caustic-based potassium hydroxide or sodium hydroxide (lye and soda ash).
So, now youíve got your reclaiming equipment. Next time, weíll show you how to put it to work.
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