Tools of the Trade - Screen Openers

Posted by Mary Yaeger – 9/6/2017

Why have screen openers in your shop? Simple. Sometimes ink will “dry up” an area of your screen which has the possibility of ruining the image area and the mesh itself. Not only does this slow down your production time, but it could cost you money in the long run. Regular use of screen openers helps prevent clogging and work delays.

Screen openers are used by screen printers everywhere. Just as there are many different screen printers, there are many different brands of screen openers. This fact alone can make it difficult to determine where to start when you buy one, but it is important to note they all have their advantages depending on the type of printing your shop does. Screen openers typically come in two forms – spray and foam spray. Both forms of sprays are meant to be used with different types of inks – water based or plastisol.

As mentioned in previous articles, plastisol ink does not “dry”. It has to go through a curing process to be considered “dry”. So, when we say an area in the screen has dried up, what does that mean in terms of plastisol ink? Depending on the mesh that you are using (especially really fine mesh), plastisol essentially gets lodged in between the mesh threads. When this happens, your standard press wipes or press wash won’t penetrate those threads well enough to get the plastisol out. This is where screen openers come into play. Screen openers are a more aggressive version of press wipes/wash. And can get in between the fine threads to remove the ink.

Water based inks are a little bit different than plastisol in this case. With this particular type of screen printing you will run into ink drying, but there are screen openers made specifically for water based inks! Most screen openers recommend regular use of screen openers. Not only does this open dried up areas on the screen, but it prevents clogging in the first place. It is important that when you use water based inks you keep the screen wet to prevent the ink from drying. Water based screen openers are another tool for screen printers to ensure they are protecting their mesh and keeping up with quality and production.

Another great aspect about screen openers is that they can also be used to clean ink and dirt from your press. While press maintenance may not be high up on a shop’s list of to-do’s it is important to remember to occasionally wipe your press down to protect it.

How to use a screen opener:

When using a screen opener it is important to remember that you are using a chemical. There are some screen openers that smell bad and there are some that smell fruity (typically oranges). That being said, remember to open a window or turn on fans as to inhale as little chemical as possible. Whenever you run into a screen clogging issue, spray the screen opener in a circular motion 6 to 8 inches away from the screen to open. Only a thin application on dried-in areas, and a few passes with a clean rag, is needed to open the mesh back up! 

Typically screen openers do not leave an oily residue or film, but it is important to check with your supplier to make sure you are getting the right product for your shop.

To learn more, visit us online at screenprintingsupply.com

Advantages and Disadvantages of Plastisol and Water Based Screen Printing

Posted by Mary Yaeger - 8/15/2017

There are two main types of ink that get used for textile printing – plastisol and water based. While plastisol is more widely known and used, the desire for a more eco-friendly shop has brought water based screen printing into the spotlight. What you will find is that both types of inks have their incredible advantages, but they also have a few drawbacks.

To get started, let’s discuss mesh. The mesh count you use is one of the most important factors to consider when printing (no matter what method you choose to print). Here is a short outline of the different mesh recommendations for inks:

• 24-40 mesh for Glitter inks
•  60-80 mesh for Shimmers and thick white underbases
•  86-110 mesh for Metallics
• 110 mesh most popular for light colors such as white ink
• 160 mesh most popular for black ink. It holds more detail than 110, but less ink will pass through the screen.
•  200-230 mesh holds high detail though the ink may need to be reduced. This mesh is great for water based inks.
• 230-305 mesh is mostly used for super fine detail half tones and CMYK process prints. This mesh is also great for water based inks.

Plastisol Ink

Plastisol is the most popular ink in the industry. It is easy to use and promoted as “user friendly”. Plastisol is not water soluble so you don’t have to worry about it drying in the screen. These inks are generally used right out of the container. No mixing needed. Plastisol is perfect for getting the opaque look on dark garments. It is formulated for printing on light and dark garments. Since plastisol does not dry in the screen, there is no worry about ruining a screen or wasting product. Plastisol does not “dry” when exposed to air. Plastisol has to be cured between 280-350F. The greatest advantage of this is being able to reuse the ink for multiple jobs. As long as the ink has not been contaminated by dirt, lint or other ink, the plastisol can be scooped off of the screen and placed back in its container.

Likewise, if you leave the ink container open for several days, the ink will be ready to use when you come back. You can also leave the ink in a screen for several days without worry of clogging or ruining the stencil. Plastisol also has the capability of wet-on-wet printing which means increased production times – saving your shop time and money.

It is generally recommended that you store plastisol at room temperature. This means keeping your shop temperature controlled. If the ink gets too hot (above 90F) there is a possibility it could start the curing process in its container. A big disadvantage of printing with plastisol is that has tends to have a greater hand-feel. This is a disadvantage because most t-shirt enthusiasts desire a vintage look and soft hand-feel to their shirts. Another thing to note about plastisol is that it should not be ironed. The iron could “re-melt” the plastisol and smear ink on your garment.

If you would like to dispose of any contaminated ink be aware that uncured plastisol is considered a hazardous waste and should be disposed of according to your community guidelines. When plastisol is cured, it is not considered a hazardous waste, but make sure you still properly dispose of it.

Water Based Ink

What plastisol can’t achieve is where water based ink steps in to play. Water based inks are great for achieving that vintage soft hand-feel that is desired by most. Water based inks soak into the fabric instead of standing on top. Water based inks are promoted as more “eco-friendly”, but it is important to keep in mind where you are getting this information from. Just because it is labeled as eco-friendly, does not mean that it isn’t free of “co-solvents” that could be petroleum based. The reason these co-solvents are used varies, but one of the reasons is meant to reduce the time and heat necessary to cure the ink on the fabric.

While water based gives most people the look and feel they want in their prints, there are a few factors that deter people from even trying it in the first place. Unlike plastisol which is ready to use right out of the container, water based ink requires a little bit of mixing math. Water based inks start out as two separate products – pigment and base. You have to add the right amount of pigment to the right amount of base to get the desired color. There are also several additives that you must consider for each type of print.

With a name like water based it is easy to assume that curing would be a simple process because in reality all you are doing is evaporating the water to cure. At a craft level, this might not be too bad. Water based inks can air dry, but not in enough time for high production jobs. For shops that are printing at an intermediate to high production level, the dryers that are required for water based inks are typically larger than the dryers used for plastisol. To help the ink cure faster, you can add what is called a “catalyst” to the ink. The catalyst allows for a fast dry time and ensures an even dry over the entire printed area. The disadvantage to using a catalyst is that it greatly reduces the life span of the ink. When you add a catalyst to water based ink the shelf life is limited to 4-12 hours.

Water based ink tends to dry in the screens if not tended to constantly. For this reason, it is important to keep a spray bottle full of water nearby to keep the ink wet. If the ink dries in the screen it will clog the mesh and ruin the screen. It is also important to consider the type of emulsion you are using. Water resistant emulsion is a MUST! Water based inks will melt or eat through any other type of emulsion. This will end up destroying your stencil and setting your print job back.

Things to Consider Before you try Wet-on-Wet Screen Printing

Posted by Mary Yaeger - 8/2/2017

Also seen on Printwear 

One of the greatest features of plastisol ink is the ability to dive into the world of wet on wet printing. Your shop is filled with orders and you are looking for a way to cut down on wasted time and get products out faster to your customers. Welcome to wet on wet printing. Being able to print wet on wet simply means that you can print successive colors without necessarily having to flash in between colors. Now, there will always be outlier print jobs (especially with dark colored garments) that will require you to flash layers, but the general advantage of wet on wet printing is avoiding the flash cure. Doing so will save you time, money and ensure that your customers get their products quickly.

The Print Order

A general rule of thumb for screen printing is to print light layers first and finish with the dark layers. It is also best practice to print from the smallest stencil to the largest. This all depends on the amount of detail that you have in your overall image. Screens with less image detail should print first. Inversely, screens with the most detail need to be printed last. This ensures that you are able to print a large design without worrying about excessive ink build up.

 Ink Smears

What you will notice with wet on wet printing is that your screens will grab ink from previous layers. This could bring your whole production to a halt if you are not careful. What happens is that thick ink layers will cause the screen to stick to the ink and smear the color. It is normal for the screens to pick up some colors from previous layers, but too much build up will smear the whole print or block out pars of the screen – ruining the stencil.

There are a few things you can do to avoid this from happening:

•       Choose a high mesh count screen (200+) with high tension
•       Use a thin ink deposit
•       Put light pressure on your squeegee

Over the course of your print job make sure to keep your ink layers thin. This reduces the chance of ink being picked up by your screens. Using a base can give the ink a short body that prints well and helps prevent smearing by allowing the ink to penetrate further into the fabric. If you notice that your screens are picking up too much ink, it would be best to take a few minutes to clean the substrate side of your screens to avoid a major headache later on.

Practice Makes Perfect

Best practice will be to print a few test shirts before going into an actual print job. If you have any questions, you can always reach out to your screen printing supplier. They can recommend the right inks for wet on wet printing. If you are having trouble with your screens picking up ink, your supplier can also recommend a reducer to ensure you get a thin ink deposit.

Wet on wet screen printing will allow your shop to work faster and more efficiently, cut down on wasted time and get products more quickly to your customers. The process takes a little patience in the beginning, but that patience will help your shop become more efficient. 

What is a soft-hand print?

Posted by Mary Yaeger

Also seen on Printwear

The feel of a plastisol print is called the “hand”. It is controlled by the type of ink and how thick an ink layer is. To achieve soft-hand prints you have to start with a soft-hand base. To achieve an extra soft-hand print on white garments – use a 230 or higher mesh count screen. Soft-hand printing can easily be achieved with soft base additives and water based inks. Distressed and vintage prints are in high demand which call for a natural feeling and more authentic touch. There are a couple of ways to achieve soft hand – water based and discharge printing.

    Water based inks

Just as the name suggests this type of ink creates a soft feel because its make up is not plastic. This type of ink tends to dry in areas if not watched carefully. You might lose some detail or fine halftone. The curing time of water based ink is slower. This ink is more transparent than plastisol and does not appear well on dark garments. Typically this wouldn’t be an issue. You can slap an under base on your garment and continue printing. Unfortunately, water based doesn’t print well on under bases. If you are going to use water based inks, it is better to print on white and light garments.

Discharge Inks

Discharge inks are your solution to printing soft hand on dark garments. It is considerably softer than printing with plastisol but it does require an under base. Discharge ink uses an “activator” that bleaches the dye out of the shirt and deposits the ink pigment in its place.  Discharge is technically still a water based ink. So you will want to avoid designs with heavy detail and fine halftones. Printing on “rich colors” such as red, purple and royal blues tend to discharge unpredictably. The inks are often contaminated by the dye in the shirt so your print could end up an off color.