F.A.Q.

Yes. By stirring the ink, this action creates “sheer” and this breaks down the “false body” inherent in the ink when it is idle. By stirring the ink you create heat which loosens the molecules of the ink and makes the plastisol ink “creamier.” Stirring plastisol ink prior to use will also show the viscosity of the ink. Never modify the ink without thoroughly stirring the plastisol first. Printers too frequently will add a viscosity reducer when they don’t need to. A simple solution is to use a stainless steel ink spatula to manually stir the ink.

Plastisol ink should be stored away from heat and sun. Never store, or keep near dryers or flash cure units. Always keep the lid on the plastisol ink bucket for a wide variety of reasons, including contamination, and because some plastisol formulations can absorb humidity in the air. Also, remember that “cold” plastisol gets thicker and stiffer and does not print well.

There are several reasons why some plastisols “build-up”. And to some degree, all plastisol ink will build-up on successive screens. Minor build-up does not cause a problem and, sometimes, it can actually enhance the look and brilliance of the print. So we will concentrate in unwanted or excessive build-up. Here are some of the most common reasons, and what you can do to “fix” this issue.

5. Artwork design. Too frequently the artwork does not lend itself to good multi-color printing. Many printers still “trap” colors, and this contributes to build-up.

6. On-contact printing presents build-up problems, as the mesh has no opportunity to “snap-back” and contributes to the “ink smear” problem. You should be printing t-shirts, hoodies and other garments with off-contact. You want about ¼ inch (the thickness of a quarter) gap between your screen printing press platen and aluminum frame.

7. Excessive off-contact can also contribute to ink build-up, as excessive squeegee pressure needs to be used to overcome the off-contact gap created by too much distance between the mesh and the garment.

8. Squeegee and Flood speeds are not matched to the ink, mesh tension and substrate.

Dye migration (“bleeding”) is caused by the dye in the polyester fabric “gassing out” during the curing process, and embedding itself in the plastisol layer of ink. There are basically only 3 ways to control dye migration (bleeding):

1. Don’t print on a garment where the dyes easily migrate under heat. Not all garments are created equal. Some manufacturer’s garments bleed less than others, because of the dyes they use, and the curing process that is used to “set” the dyes.

2. Use a plastisol ink specifically designed to control dye migration – called low-bleed polyester inks. There are significant differences between the various brands of low-bleed polyester plastisol inks…so do your due diligence and test prior to using.

3. Cure at lower temperatures, and use jet-air as this is a more “gentle” and consistent type of heat. Avoid using a dryer this is entirely quartz as quartz tubes are extremely hot and not as controllable as I.R. panels and hot-air.

Cracking ink is almost always under-cured. Of course if you are printing on a substrate that has has enormous stretch, and the plastisol ink you are using does not have equal stretch characteristics, then the ink could also crack. Add a “stretch additive” or “soft-hand extender” to the ink and this will frequently solve this cracking issue. Crocking is not to be confused with cracking. Crocking is a condition where the ink actually can be rubbed off. Of course first make sure the plastisol is thoroughly cured. If high-grade pigments are used by the plastisol manufacturer, crocking is usually not a problem. Red plastisol is generally the problem, as some manufacturers use a lesser-grade pigment – automotive grade red pigments are expensive, so spend the extra money for the good plastisol.

The most accurate method of determining ink cost is to weigh an un-printed shirt, then print your design on it, then weigh it again. This weight will exactly tell you – given your particular print environment (i.e. mesh count, emulsion thickness, pressure, etc.) – how much ink you are using. Then simply determine your cost of ink per gram, and there is your cost per print.

A brief and somewhat “technical” answer is when the entire ink film thickness reaches its specified cure/fusion temperature. Various ink series and various ink manufactures vary these specifications.

The Multi-Tech Dynamic Ink Series all cure around 280-F and are classified as low-fusion inks. Note that thicker ink deposits take more time to reach their specified cure/fusion temperatures.

For Multi-Tech Dynamic Ink, the cure time  will range from 40 to 60 seconds. However, please note that many factors help determine how long it takes to completely cure an ink. Most importantly is the “Heat Absorption” rate…which is different for various garments.

For example, are you printing on light or dark garments? What is the weight of the garment? Are you print hoodies, or shirts or jackets, etc.? Also,  does the print have a thick ink deposit? 

Measuring the ink temperature on the garment, as it passes through the dryer, is the best way to determine the time it takes for your inks to cure properly. Remember it is important that the entire ink film thickness reaches the specified cure/fusion temperature. We recommend Lawson Thermo-Tels for measuring temperatures on the garment as they are far superior to “heat guns”.

A “Wash Test” is always the best method, especially when using garments you are not already familiar with using. What most printers do in “real life” is the standard “Stretch Test”. If you see cracking of the ink, your inks are likely under-cured.

Most inks will “gel” (flash) when the ink film reaches 220°F to 230°F. There are 3 primary  factors that affect the “gel” or “flash” of the ink: the temperature of the flash unit, the distance of the flash unit from the printed image, and the time the printed image is exposed to the heat. As a rule, you want to flash the ink film until it is just “dry to the touch”. Over-flashing inks can cause intercoat adhesion problems and make the inks very “tacky”. Check your flash cure unit to see if it has temperature and airflow controls. These can help you better control your flash cure process.

The answer is Yes, but why would you want to do that?  A  flash cure unit is not a good substitute for a conveyor dryer. Using just a flash cure, you could easily overheat the film surface yet under-cure the rest of your ink film, at the same time! I would only use if you do not have a conveyor dryer.