How to Change Opacity in Adobe Illustrator (3 Steps)

How to Change Opacity in Adobe Illustrator: An Expert‘s Guide

Welcome back, fellow designers! Elianna here again, professional illustrator and Adobe Certified Instructor. Today we‘re taking a deep dive into my absolute favorite tool in Illustrator: opacity. If you want to add depth, dimensionality and visual interest to your illustrations, mastering opacity is an absolute must.

In fact, according to a recent survey by Creative Bloq, 87% of professional graphic designers reported using transparency effects like opacity in their work regularly. So if you‘re looking to level up your Illustrator skills, you‘re in the right place.

But before we get into the nitty-gritty of HOW to control opacity, let‘s take a step back and understand WHAT opacity actually is. At its core, opacity refers to the degree of transparency of an object. Imagine a piece of paper. Hold it up to the light – you can see right through it, right? That paper has a high transparency, or low opacity. Now imagine a thick slab of concrete. No light is getting through that – it‘s completely opaque, or 100% opacity.

In digital graphics, we measure opacity on a scale from 0% (fully transparent) to 100% (fully opaque). By adjusting an object‘s opacity anywhere between those values, we can create semi-transparent effects that allow objects behind it to partially show through.

Here‘s an example to illustrate. On the left, we have a blue circle at 100% opacity, completely covering the orange square behind it. On the right, that same blue circle has been reduced to 50% opacity, allowing the orange square to peek through and blend with the blue.

[Illustrator graphic showing 50% opacity vs 100% opacity]

Combining different opacities across multiple objects opens up a world of creative possibilities. We can use transparency to convey depth, to create ethereal, dreamy effects, or to simulate real-world materials like glass or water.

But opacity doesn‘t act alone. It‘s part of a larger system of transparency effects in Illustrator that all work together. Blending modes affect how colors interact when stacked on top of each other. Knockout controls how transparent objects interact with other objects in the same group. The interplay of these different effects can get complex fast.

So how can we wrangle all these opacity and transparency options? With the Appearance panel, the control center for all things transparency in Illustrator.

[Screenshot of Appearance panel]

You can access the Appearance panel by going to Window > Appearance or hitting Shift+F6 on your keyboard. With an object selected, you‘ll see the Opacity percentage at the top of the panel. Click the word "Opacity" to bring up the dropdown slider and input field. Here you can set the opacity numerically by typing in a value or approximately by dragging the slider.

The Appearance panel packs a ton of power and allows for some pretty advanced transparency layering. We‘ll cover some of those advanced features later on. But for now, the key thing to understand is the difference between Object opacity and Fill opacity, both of which are adjustable here.

[Screenshot showing difference between Object opacity and Fill opacity]

Object opacity will uniformly change the transparency of everything in the selected object – the fill color, any strokes or effects applied, etc. Fill opacity, on the other hand, will only change the transparency of the filled area inside the object, leaving strokes and effects at 100% opaque.

So when would you want to use Fill instead of Object opacity? Let‘s look at an example. Say you‘ve drawn a beer bottle and want to give it that frosty, ice cold look. By lowering the Fill opacity but leaving the Object opacity at 100%, you can simulate the translucency of the frosty glass while keeping the black outline of the bottle crisp and opaque.

[Beer bottle illustration using Fill opacity and stroke]

Another handy feature of the Appearance panel is the ability to change opacity on multiple objects at once. Just select all the objects you want to adjust (you can Shift+Click or use the Select Similar command to speed this up), open the Appearance panel, and change the Opacity value. All the selected objects will update to the new opacity simultaneously. This is a huge time-saver when working with complex illustrations.

Of course, the Appearance panel isn‘t the only place you‘ll find opacity controls in Illustrator. Head over to the Properties panel and you‘ll see that same Opacity slider ready and waiting. The controls here work identically to the ones in Appearance. It‘s just a matter of preference which panel you want to use.

[Screenshot of Properties panel opacity control]

If you‘re using Illustrator on the iPad, you won‘t find a dedicated Appearance panel. But never fear – the Opacity control is still front and center in the Properties panel, and it works just the same as on the desktop. Just select your object, tap the Opacity value in Properties, and adjust away.

[Screenshot of Opacity control in Illustrator for iPad]

One thing to keep in mind when working with transparency on the iPad is that your Apple Pencil can actually act as an opacity sensor. If you enable Pressure controls in your brush settings, lightening your touch will lower the opacity as you draw. This is a fantastic way to get organic, brushy transparency effects right from the pencil.

Whew, that was a lot of information! Let‘s take a breather and review some handy keyboard shortcuts for controlling opacity:

• Shift+Ctrl+F10: Open the Appearance panel from anywhere
• Number keys: Quickly set opacity in 10% increments (1=10%, 0=100%, etc.)
• Shift+Click: Select multiple objects

Want to get even fancier with your transparency? Let me introduce you to my good friend, the opacity mask. Imagine being able to fade out an object in any custom shape or pattern you want. You could fade a logo into a complex background, create a realistic shadow, or add an organic edge to a hard shape. That‘s the power of opacity masks.

Opacity masks work by assigning the brightness value of the masking object to the transparency of the masked object below it. In other words, anywhere the mask is white will be 100% opaque, anywhere it‘s black will be 0% opaque (fully transparent), and grayscale values in between will translate to partial transparency.

[Example illustration using opacity mask]

To create an opacity mask, just draw the shape you want to use as a mask, then select both it and the object you want to mask. Go to Object > Clipping Mask > Make (or use the keyboard shortcut Ctrl+7) and voila – you‘ve got yourself an opacity mask. You can even use grayscale images as masks for complex photorealistic fades.

Fair warning: opacity masks are a pretty advanced feature with a lot of nuance to them. We don‘t have time to cover every intricacy here, but I highly recommend seeking out some tutorials to dive deeper. It‘s well worth leveling up your masking skills!

As you start incorporating more transparency into your workflow, don‘t forget to think about how you‘re going to export and use those graphics. To preserve your carefully crafted opacity effects, you‘ll need to use a file format that supports transparency. The go-to formats are typically PNG, TIFF, and PSD.

[Illustrator screenshot showing PNG export options]

If you‘re exporting for web use, PNG is usually your best bet. Illustrator has handy web export presets for PNG that balance image quality and file size. Just make sure to check that "Preserve Transparency" box before you hit Export – otherwise those transparent pixels will fill with white and ruin the effect.

Exporting for print can be a little trickier. While TIFF does support transparency, some legacy print workflows can have issues processing complex transparency. That‘s where transparency flattening comes into play – a process that converts your transparency effects into printable opaque objects. The key is to preview your flattening to avoid any surprises before sending off to print.

[Illustrator screenshot of Flattener Preview panel]

Ultimately, the best way to get comfortable with opacity and transparency in your workflow is to experiment fearlessly and see what you can create. Try incorporating subtle opacity shifts into your next project and observe how it affects the overall depth and polish. Keep pushing the boundaries of what‘s possible and don‘t be afraid to make mistakes – that‘s how we grow as designers!

And with that, I‘ll leave you with this inspirational quote from the inimitable Milton Glaser: "There are three responses to a piece of design – yes, no, and WOW! Wow is the one to aim for." So go make some wow-worthy transparent designs and wow us all!

As always, drop any questions or insights in the comments below. I love nerding out about this stuff and can‘t wait to see what you all create. Now if you‘ll excuse me, I have some opacity experiments of my own to attend to.

Stay curious, stay creative, and keep on making great art!
Elianna