Screen Making: The Direct Emulsion Method

Using the direct emulsion method, the screen mesh is coated with a light-sensitive emulsion. This article covers the basics of screen making, including screen tensioning, fabric abrasion and degreasing, coating and drying the screen, and taping the screen. 

There are many different ways to make a screen. The easiest way, of course, is to have someone else make it for you. Please don’t accuse me of being flippant. I am dead serious. If you are not screen printing full time, buying a screen is the most practical way to go. This is the way many of my friends, who are sign makers, do it. Making screens requires an investment in specialized equipment and it occupies valuable floor space. What’s more, you need to know what you are doing or you can be assured of problems. Plus, screen making takes time. That’s valuable time that a small shop owner could invest in more fruitful endeavors, such as selling, so you can expand your business base.

On the other hand, if you want to learn how to do it yourself, this article will cover the basics of screen making, using the direct emulsion method. In using this photographic method, the screen mesh is coated with a light-sensitive emulsion.  A sharp image usually requires several screen coatings. Typically, the mesh should receive two coats of emulsion on both screen sides. Data sheets generally specify the number of coatings for each emulsion and mesh count. Although multiple coatings don’t dramatically increase stencil thickness, they fill in the recessed areas. Several coatings will ensure a more uniform stencil surface, good print quality and increased stencil life. If the emulsion isn’t thick enough, a “sawtoothed” effect — a jagged or stair-stepped edge — can occur.

After the emulsion dries, the film positive is positioned over the coated screen. The screen is then exposed to ultra-violet light, which hardens the emulsion, which is not covered by the image on the film positive.  After the exposure process, the emulsion is washed out with water from areas that the image on the film has covered or protected from the exposure. After a few other finishing touches, you should be ready for printing. That’s it for the Reader’s Digest version on emulsions and screen making. For the rest of the story you will have to read on.

Why Direct Emulsion?

There are, of course, many different ways to skin the proverbial cat. Other methods include using different types of direct and indirect capillary films. One capillary film is cut, reverse-weeded and then adhered to the screen, while another type is applied to the fabric, then exposed. A final type is first exposed, then adhered to the mesh.   

So why have I chosen to write about direct emulsions and not capillary films? Part of the reason is that this is the method used when I worked for fleet graphics screen printers.  More importantly, for long production runs, stencils made using direct emulsions are more durable. Sure, the direct emulsion has its disadvantages. First and foremost is its level of difficulty. It takes a certain degree of skill to get an even coating of emulsion on a screen. That’s important, because and uneven coating on the print side of the screen (that’s the side that make contact with the substrate) can result in print imperfections. In order to achieve a sharp print, you will need a smooth coating with uniform thickness. Even if you know what you are doing, your results are often in the hands of the fates and how the emulsion dries in the screen.  

Screen Tensioning

The ideal tension to which  you stretch the screen will  depend on the mesh that you use.  Fabrics with a mesh count up to 110 can be tensioned as high a 50 Newtons. On the other end of the spectrum, fabrics with mesh counts of 230 and higher should be tensioned between 24 and 26 Newtons.

Be aware, though, that within a matter of hours, after stretching the screen, the tension will drop off. How much tension will you lose? You’d be amazed. It is not uncommon to tension a screen to 25 Newtons, and after having an unhurried lunch, return to find that the screen tension has dropped to 20 Newtons. In fact, this loss of tension is a very common occurrence. Don’t be alarmed though, even after the tension drops off, most screens will be within industry standards.  

Screens, which are not within these standards, should be restretched. The advantage of the retensionable frames, such as the Newman roller frames, is that you can retension the mesh, when the tension drops off. Regardless of what type of frames you use, if you are going to stretch your own screens, you will need to invest in a tension meter.  The cost for these instruments range between $350 and $450.

Screen Print Fabric Preparation  

Before you coat the screen, you must prepare the fabric. When the topic of fabric preparation is discussed, you will  frequently hear two terms used: abrading and degreasing the fabric. While these steps probably sound like the most inglorious and unheralded tasks in the screen print production cycle, they are undoubtedly two of the most important steps.  Fabric preparation is critical to creating a high-quality stencil. Improper mesh preparation can cause pinholes and stencil durability problems.

Let’s start with abrading. This step only applies when you are using capillary films. When you use direct emulsions, abrading is not only unnecessary, but it is not recommended. Here’s why. The process of abrading roughs up the treads and can weaken the mesh, shortening its life. For direct emulsions, don’t do it. On the other hand, if you are using a capillary film, abrading is absolutely necessary.

By giving the fabric some tooth, abrading  improves adhesion of the capillary film to the mesh. Historically, screen printers have used household cleaners, such as Comet, to abrade fabric. While these cleaners are readily available and inexpensive, the large grit size of the abrasive used in them can damage the mesh threads and leave residual particles in the fabric. The better choice is to buy the recommended commercial cleaner from your distributor and to apply the cleaner with a good hard bristle brush. This process is not unlike scuffing up a substrate to give it some tooth before painting it.

Typically, abrading is only performed on new fabric. After a screen has been abraded, do not use any cleaner with an abrasive.  Not only is this unnecessary, additional abrasion of the screen could damage the fabric.  Screen fabric only needs to be abraded once in its life, but must be degreased every time before adhering a stencil to it.

Fabric Degreasing

The second step in the fabric preparation process is degreasing. Whether you are using direct emulsion or capillary films, you must degrease the screen every time before coating a screen or applying a capillary film to the mesh. The degreasing process removes any oils or other contaminants from the screen fabric, which can prevent good adhesion of the stencil and well as other problems resulting from contamination, such as pinholes and fisheyes. 

You can buy a screen degreaser, such as Ulano’s Screen Degreaser Liquid No. 3, from your screen print supply distributor. This is ready to use degreaser that you can use straight from the bottle with not mixing involved. There are many different commercial degreasers on the market. Some of these degreasers contain wetting agents, which aid the flow out of the emulsion in the coating process.  If you are confused about which to use, consult your distributor. 


As an alternative, some screen printers will use a cleaner, such as Simple Green or dishwashing liquid. These cleaners should be avoided because they can leave a residue in the mesh, which can inhibit stencil  adhesion. Printers have also used  caustics, such as Trisodium Phosphate (TSP), for either abrading or degreasing. These  highly caustic chemicals should not be used because they can damage the fabric. The point is the are no shortcuts or cheap solutions. You get what you pay for. Stick with the commercial products from reliable companies.

In addition to the standard fabric preparation products,  combination abrader and degreasers are also available on the market, such as Ulano #23 Roughening/Degreaser. Chromaline and KIWO also manufacture dual purpose products.

The process of degreasing a screen is really straightforward and simple.  First wet the fabric with water.  Then spray the mesh with the degreaser.  Using a soft brush, scrub both sides of the screen, with a circular motion.  The scrubbing process, which only takes about a half of a minute per side,  will generate suds.  

After scrubbing the screen, wait a half of minute before rinsing the screen with a light spray of water. Make sure that the screen and frame are rinsed thoroughly. Do not use a pressure sprayer to rinse the screen.  If cleaned correctly, the fabric surface should exhibit an even film of water. If  the water beads up, the fabric has not be sufficiently degreased.

After rinsing, stand the screen on a side of its frame and allow it to dry.  Drying the screen vertically, will prevent any dust from settling on the mesh. The screen preparation area of your shop must be as clean and dust-free as possible. Mesh static can also attract dirt.  Dust, which has settled on the screen, will prevent the emulsion from adhering properly to the fabric and will show up as pinholes.  Do not try to accelerate the drying process by blowing off the screen with an air hose. If there is any oil in the air lines, you potentially could deposit greasy contaminate just after you degreased the screen.

After degreasing the fabric, be very careful in handling the screen.  Touching the mesh will leave oils from your skin on the screen surface.  Fingerprints from the offender will be captured after the screen is coated. So keep your mitts off of the mesh.


Once the mesh is dry, a good practice is to coat it shortly after degreasing. After coated screens have dried, they  should be stored vertically in a dark room. Because heat and humidity adversely affect coated and stored screens, they should be used within a week.

Screen Print Emulsions

The emulsions on the market today generally consist of a two-part system: the base and the sensitizer. Emulsions are manufactured to cover a wide range of applications and possess a variety of characteristics. If you need help in selecting the right, consult your screen print supply distributor.

Unused emulsion sensitizer and bases should be stored in non-metallic containers in a refrigerator.  Stored near heat or bright light, these chemicals deteriorate and produce poor  stencil quality.  Also, avoid storing these chemicals at freezing temperatures, which could potentially change the chemical properties.  In addition, sensitizers and bases should not be stored beyond their maximum shelf life.

Before mixing the emulsion base and sensitizer, the sensitizer should be completely dissolved.  To prevent any sensitizer lumps from getting in the emulsion, strain the sensitizer with a paint strainer.  Always use clean instruments, containers and utensils in the mixing process.  The emulsion should be mixed a few hours before use to dispense any air bubbles, which may develop while mixing.  Refrigerated emulsions should be removed from the refrigerator  a few hours before use so that the emulsion reaches room temperature, allowing its viscosity to stabilize. 

After the emulsion is ready, it’s time to coat the screen using a tool called a scoop coater.  I confess that when I first saw this process, I was somewhat intimidated, because coating the emulsion takes a little skill.  This skill, however, is not difficult to master. If you have a good teacher, you can learn to coat your own screens in less than an hour. 

Coating the screen should take only one pass per coat. Some printers try to scrape off any excess emulsion. In the scraping process all you do is generate bubbles in the excess emulsion.  On subsequent passes the bubbles in the emulsion will cause streaks in the coating.

Several coatings of the screen are typically required to produce a sharply defined image.  Typically, the mesh should receive two coats of emulsion on both sides of the screen.  Data sheets generally advise the required number of coatings for a specific emulsion and mesh count.  The multiple coatings do not dramatically increase the thickness of the stencil, but fill in the recessed areas.  Several coatings will ensure a more uniform stencil surface as well as aid in the production of good print quality and increase stencil life.  If the emulsion is not thick enough, “sawtooth”, which is a jagged or stair-stepped edge of an image, can also result.

The screen coating process should be undertaken under subdued light and in a dust-free environment.  Usually, the last coating is applied on the squeegee side of the frame. After you have coated a screen with emulsion, dry it horizontally with the squeegee side of the frame facing up. Many screen printers will build a drying rack for this process. As the emulsion dries, some of it will flow to the opposite or print  side of the mesh.  By drying the screen in this manner, the emulsion on the print side will be slightly thicker than on the squeegee side. This is important, because in the exposure process the film positive is laid on top of emulsion on the print side, and the heavier coating ensures that the stencil will hold up better during a production run.   

Drying Screen Emulsion

After you coat a screen and before you expose it, you must dry the emulsion. Proper drying is critical. As the water in the emulsion evaporates, the solids crosslink or bind together, and the emulsion hardens. Water in the emulsion prevents the crosslinking process from occurring.   If the emulsion is not completely dried, the stencil can  break down during the printing process.

The environment in which a screen is dried is very important. Trying to dry a screen in a room with high humidity will prevent the water in the emulsion from evaporating completely. In fact, high humidity can even result in the emulsion absorbing moisture.

To control the humidity in the screen drying area, you will need to buy an inexpensive thermometer and hygrometer for measuring temperature and humidity and a dehumidifier.  The screen making department should also be air conditioned, which will also help control humidity during the summer. When I worked for one screen printer their objective was to maintain 38% humidity at 72°F. When air temperatures are higher, the air will absorb more water vapor. Extremely high heat, though, can cause problems. When ambient temperatures approach 100°F, emulsion can start to harden even before the screen is exposed. Coated screens can also be affected by heat and humidity during storage.  That’s why coated screens should be used within a week.

To accelerate the drying process, many printers direct a fan at the coated screen.  While a fan usually does a good job of circulating air and drying the emulsion, it can also circulate any dust in the room, depositing the particles on the screen. Wherever the dust settles, it prevents light from reaching the emulsion and hardening during exposure.  After the exposed screen is washed out, the emulsion covered by the dust particles is also washed out, resulting in pinholes. While most pinholes can be touched up with blockout, the time spent to doctor up the screen is wasted time that slows down production.  

Getting the Right Exposure

Before exposing the screen, clean the glass of the exposure unit.  Dust and dirt often result in pinholes. In exposing the screen, position the film positive on the contact frame. The emulsion (or right-reading side) of the film should face up so that it makes direct contact with the emulsion on the screen.  The frame is the placed over the film positive.  With the well side or squeegee side of the screen facing up, the blanket is positioned inside the frame.  The blanket ensures good pressure and contact between the coated screen and the emulsion on the film positive.  When the ultraviolet light source is turned on, the exposure process begins.  

Shortly after exposure, wash out the exposed screen. Place the screen in a vertical position in the wash out booth.  Thoroughly wash both sides of the screen using cold or lukewarm water with a medium to hard shower spray.  Never use a pressure sprayer for this process.  Excessive pressure could destroy the image in the screen.

After completely washing out the stencil image, wipe the excess water from the screen with a good quality chamois or clean, absorbent newspaper. If the newspaper sticks to the emulsion on the squeegee side of the screen, the exposure was probably inadequate.  The result may be poor image definition, poor detail resolution and poor stencil chemical and mechanical resistance.

Another way to check for underexposure is to simply touch the emulsion. If it feels slippery or slimy, the emulsion most likely has not hardened properly.  During printing, emulsion could potentially deposit in the open areas of the mesh, causing clogging.  Use an air hose to blow out the open areas.  Then allow the screen to thoroughly dry.   

Correct exposure requires an appropriate amount of light and time. Important light considerations include:

• The quality of light;

• The consistency and distribution of light;

• The quality of the film positive—the image areas of the film must be perfectly opaque, while the film base must be optically clear.  In addition, the image areas must have crisp, sharp edges;

• The emulsion characteristics;

• Different fabrics hold varying levels of detail. Orange fabric, for example, allows more detail than white.

Taping Your Screens

To prevent ink leaking form the squeegee side of the frame to the substrate side of the frame, screen printers apply tape between the frame and the mesh.  Taping is done after the screen is shot and the image is washed out.  It is very important to allow the screen to completely dry.  Any moisture will cause a water-based adhesive to deteriorate.  This can result in ink leakage during printing and adhesive residue on the frame and mesh following tape removal. 

Solvent-resistant block out tape should be used in the masking procedure.  The quickest and easiest method for taping a screen is one that I learned in the  Screen Print Technical Foundation (SPTF) workshop “Screen Making: Basic To Professional”.

In the procedure, you first tape the corners and then you apply tape along the sides. Be sure that the tape is completely flat, without any wrinkles. Wrinkles are points where ink leakage can begin.  In the taping process, use the fewest pieces of tape to accomplish the job.  Tape adhesive can ooze at the edges of any tape product.  During printing, the squeegee can transfer pieces of oozing adhesive to the open areas of the screen. This adhesive contamination can inhibit ink flow, causing spotting and pinholes.  After the tape is applied, then coat the screen using liquid block out between the stencil and the block out tape.

For a step-by-step description of the taping process, read my article: How To Tape Retensionable Screen Print Frames.

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About Jim Hingst: After fourteen years as Business Development Manager at RTape, Jim Hingst retired. He was involved in many facets of the company’s business, including marketing, sales, product development and technical service.

Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer.  Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.

Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for  publications, such as  Signs Canada, SignCraft,  Signs of the Times, Screen Printing, Sign and Digital Graphics and  Sign Builder Illustrated. He also posted more than 325 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published.  Vinyl Sign Techniques is available at sign supply distributors and at Amazon. 

© 2016 Jim Hingst