When it comes to choosing a screen printing emulsion, one of the most misunderstood aspects is the concept of “thickness.” Printers often say an emulsion feels thick—or too thin—but what exactly are they referring to? Is it the viscosity of the liquid emulsion or the solids content that remains after drying?

Printers frequently assume that a thick-feeling emulsion will coat more screens, last longer on press, or contain more solids. But these assumptions can lead to misinformed choices that affect coating quality, stencil durability, and overall screen room efficiency. Let's clear things up.

Viscosity vs. Solids Content: What’s the Difference?

A high-viscosity emulsion isn't necessarily high in solids—and vice versa. Let’s break it down in simple terms:

• Viscosity is how thick or fluid the emulsion feels when you scoop, stir, or coat it. It’s measured in centipoise (cP) and influenced heavily by temperature. Colder emulsion = thicker viscosity.
• Solids Content is how much actual material is left behind on your screen after the water and solvents evaporate during drying. Higher solids = higher stencil build with fewer coats.

EXAMPLE: Take Chroma/Tech® PL, for example. It’s one of the highest solids emulsions we offer—around 50% solids—but its viscosity is only 4600 cP at 25°C, which feels relatively fluid when coating. That means you get the build of up to four coats of a diazo emulsion with just a one-on-one coat using Chroma/Tech PL. It flows easily into the mesh, coats smoothly, and dries fast—all while giving you a rock-solid stencil. It’s thick where it counts—in performance, not just in feel.

Common Misconceptions About Emulsion Thickness

A common misconception is that high viscosity automatically means high solids—or that a thicker emulsion equals a better stencil. But viscosity is simply a measure of how fluid or resistant to flow the emulsion is. It’s highly affected by temperature: a low-viscosity emulsion stored in a cold room will thicken up noticeably, while a high-viscosity emulsion in a warm space may become more manageable.

Meanwhile, solids content—not viscosity—is what truly determines the emulsion’s performance after drying. High-solids emulsions leave behind more actual stencil material once water and solvents evaporate. This gives you a thicker, more durable stencil with fewer coats.

So while high-viscosity emulsions do deposit more emulsion per pass, they won’t necessarily coat more screens. And just because an emulsion feels thin doesn’t mean it won’t deliver high build and strong performance.

Why Solids Content Matters More Than Feel

When you prioritize solids content over how an emulsion feels in the scoop coater, you'll get real, measurable advantages:

• Fewer coats needed to achieve the right emulsion-over-mesh (EOM) ratio
• Faster drying times due to lower water content
• Stronger, more durable stencils that resist breakdown
• Improved edge definition for fine detail and halftone printing

In short, when choosing an emulsion, don’t just go by feel. Look at the numbers—and what the emulsion delivers after it dries.

Application Tips Based on Viscosity

Understanding viscosity can help you apply emulsions more effectively:

Choosing the right emulsion viscosity helps you control stencil build, ease of coating, and overall print quality. Use low-viscosity for smooth, detailed prints and high-viscosity for thicker deposits or specialty applications.

Find the Right Emulsion for Your Workflow

At Chromaline, we know that emulsion isn’t one-size-fits-all. Viscosity affects how an emulsion handles, while solids content affects how well it performs. Understanding the difference between the two will help you choose the right emulsion for your mesh and ink, improve stencil durability and performance, and save time in coating, drying, and reclaiming.

Need help choosing the best emulsion for your setup? Contact Chromaline's technical team for more information.