Screen Print Frequently Asked Questions

What do I use to clean ink from screens?

There are several different types of screen wash, including "environment friendly" screen wash products. Mineral spirits can be used for general clean up of squeegees and spatulas. We recommend that you consult your local city and state regulations for the proper storage and disposal of any screen wash products.

What is the "shelf life" of your products?

By maintaining proper storage conditions, plastisol inks can have a shelf life of 2 years or more, depending on the ink product. Two-part inks, such as nylon inks, once mixed usually have a limited shelf-life. Refer to your inks' product bulletins. After time, inks should be stirred as separation can occur.

What does "flash" mean?

"Flash" refers to when a printer heats the surface of an ink so it is dry to the touch, but not cured. It also can refer to the actual "flash cure unit". Flashed inks are not cured inks!

What does "cure" mean?

"Cure" occurs when the entire plastisol ink film fuses and becomes a single solid entity. For an ink to fuse fully, the entire film thickness must reach its correct cure temperature. Different inks will have different cure temperatures.

Why is "off-contact" printing important?

Screen-printing was designed as "off-contact" so that the ink will release from the screen once the squeegee has passed the desired image area. Without off-contact, the screen will not lift up out of the ink creating an undesirable print effect.

Are plastisol inks considered hazardous and are they safe to use on children's garments?

Plastisol inks when properly handled and used are considered "non-hazardous". Lead-free plastisol inks properly applied are considered safe for children's garments. Some children's sleepwear may require "flame-retardant" inks. Always check the MSDS (Material Safety Data Sheet) for any product you are going to use.

Are your inks safe to use?

Yes, used properly according to our recommendations, our inks are considered safe. Always check the MSDS (Material Safety Data Sheet) for any product you are going to use.

How or why should I modify an ink and when?

Knowing how, why, and when to modify an ink comes with experience. Most commonly, printers modify inks with reducers to bring down viscosity when inks are too thick, or with soft hand extenders to soften the hand or feel on white or light colored garments. Be sure to follow the manufacturers' guidelines and USE a scale. Be careful! Over modifying an ink or using incompatible products may create problems.

Why are there so many different "whites"?

Because it is such a critical color, ink manufacturers formulate specific white inks to accommodate the wide range of garments and applications printers are likely to run into. Printers can select white inks based on such factors as bleed, opacity, flash and cure characteristics, or printability.

What is the best "white" to use?

Unfortunately, there is no simple answer to this question. Ask yourself what you want from your white ink. Your answer should depend on the garment, art, desired effect, press, dryer, etc. Give us a call to see which white we recommend for your printing needs.

Why is my ink so thick and what can I do or use to thin it?

Plastisol inks can thicken over time, just sitting on the shelf. We always recommend that you try stirring or mixing the ink before each use. This will help break down the "false body" that inks can get after long periods of storage. If stirring or mixing is not sufficient, use a "Curable Reducer" at the recommended percentages.

At what temperature do your inks cure?

The short answer is when the entire ink film thickness reaches its specified cure/fusion temperature. That temperature is provided on your specific ink's product bulletin. Keep in mind that thicker ink deposits (e.g., High Density) take more time to reach their specified cure/fusion temperatures. Faster fusing or low cure inks will reach their fusion or cure temperatures more quickly than conventional inks.

How long does it take for your inks to cure?

There is not a single easy answer. Many factors play into how long it takes to completely cure an ink. Are you using an electric dryer or a gas dryer? Does the print have a thick ink deposit? Are you printing on T-shirts or fleece? 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 that it is important that the entire ink film thickness reach the specified cure/fusion temperature.

How do I test to make sure my inks are cured?

A "Wash Test" is the best method. Take a sample print, cut it in half, and wash it 3 to 5 times in a conventional washing machine with 3 pairs of jeans or towels. Set the washer for 'Hot Wash/Cold Rinse'. Set the Dryer for 'Cotton/High' and dry for 30 minutes. Complete 3 to 5 wash cycles and compare the "washed" sample to the "unwashed" sample. If you see cracking of the ink film or ink loss, your inks are likely under-cured.

What temperature and what length of time are needed for your inks to "flash" cure?

Most inks will "gel" (flash) when the ink film reaches 220°F to 230°F (104°C to 110°C). There are 3 factors that affect the "gel" or "flash" of the ink: the temperature of the flash, the distance of the flash 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 inter-coat 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.

What happens if I don't cure the ink properly?

Many things, none of them good! Typical problems that arise from improperly cured inks include: ink washing off the garments, cracking of the ink film, loss of color, and bleeding of the garment color(s) into the ink film.

Why do I need to "flash"?

There are several reasons. Flashing enables you to print one coat of ink on top of another - e.g., a color on a white base. You also might flash an ink to keep wet ink off the back of your screens. Some inks, such as glitters, metallics and high densities, are not designed to be printed "wet-on wet". They should be "flashed" when printing in sequence.

Can I cure my inks with a flash cure unit?

We do not recommend it! Although it is true you might be able to get the ink hot enough, a flash cure unit is not a good substitute for a properly operating 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! Not a good idea - don't do it!

How do I know if my inks are cured properly?

Your printed garments pass the wash test! (See above - "How do I test to make sure my inks are cured")

How do I measure ink temperature?

There are 3 basic and easy-to-use temperature measurement devices you can use. First, a "heat tape" can be applied to the garment before it passes through the dryer. The tape will indicate the peak temperature of the garment within the dryer. Second, an infrared "Ray-Gun" can be used to measure the surface temperature of a printed garment as it exits the dryer. All you have to do is point the gun at the garment as it comes out of the dryer. And third, a "Thermo-Probe" can be placed in the "wet" ink film or on the garment to measure real-time temperatures as it passes through the dryer. Recording those temperatures at say, five second intervals, will give you a good profile on how well your dryer is working. You may be surprised with the results.

Nylon Printing

Can I use 'regular' plastisol to print nylon jackets or do I need special nylon inks?

Our nylon series inks are specifically formulated for nylon jacket and woven nylon materials. They have been formulated for superior adhesion and abrasion resistance. Adhesion to nylon is difficult to achieve with regular plastisol inks, but many people have had success using regular plastisols on nylon by adding an adhesion catalyst to the ink.

Why is the ink coming off the jackets even though I used "nylon ink"?

Did you use catalyst? Did you mix it correctly? Was the ink properly cured? These are the first things you should determine. It's possible that the jackets or nylon materials you have contain a water-repellant coating on them. This coating often prevents inks from properly adhering to the material. Try cleaning an area of the nylon with Rubbing Alcohol. Then place water droplets on the area you cleaned and the area you didn't touch. If the water is absorbed more quickly into the area that you cleaned with alcohol, the jacket likely has a coating. Clean the areas of your jackets that you will be printing before you print. Change your cloth or rag frequently while cleaning; you don't want to re-deposit the coating back onto the jacket.

Can nylon inks be printed without catalyst?

Yes they can, but not on most Nylon materials. Nylon inks can be printed on cotton or cotton/poly blends without having to use a catalyst; but nylon inks tend to have a stiffer hand feel than other regular plastisol inks.

Tips for Printing Nylon Jackets