by infinite_resolution

Created

April 22, 2009

Mysteries of the Eraser Tool — Revealed!

Contributed by Brenda Sutherland, Illustrator Team Rowing Captain

In my last post, I talked about <a href=””>Pathfinder and how Illustrator uses the Pathfinder engine to power other great features as well. One of those features is the Eraser Tool, which erases away parts of an object as if were a vector Art Gum.

You might wonder how this could be tied to Pathfinder, and more importantly, how an understanding of its underlying technology will benefit you. Let me explain it this way; the tool can’t read your mind, although it might sometimes seem that way as it erases some objects and not others. I for one love a great mystery, but I think this tool will be even more useful to you if I demystified it by sharing how it works, what it’s limitations are, and the best ways around those limitations.

If you have used the tool, you have probably noticed that it’s very similar to a calligraphic brush. In fact, it can even be used with a pressure sensitive tablet to vary its size, angle and roundness. Double clicking on the tool opens up its Option dialog, where you can customize it’s settings.

EraserDialog.jpg

The options dialog isn’t the only place were settings can be changed. Just like the Calligraphic Brush, the diameter can be changed by using the bracket keys, ] and [ respectively to increase and decrease the size.


If you have already made the assumption from this that the tool is in fact, creating a Calligraphic Brush stoke then you get a gold star! That’s exactly what it’s doing. The next thing it does is expand the brush stroke in the same way you would manually by choosing Object>Expand, to make it a simple or compound path, and no longer a brush stroke. Then the next step is it runs Pathfinder to cut away the Eraser Tool created object from either the current selection, or if there is no current selection, all valid objects that are touched by the eraser object. Whew, that’s a lot of steps! But the Eraser tool does all of this behind the scenes, so all you need to think about is what you want to erase.As simple as this tool is to use, the results are not always exactly what you expect. Now that you understand how it works, let me give you some tips on how to get the results you are after ALL the time:

  • The Eraser tool works based on selection. When you have an object selected, it will erase only that object. When there is no object selected it will erase any valid object it comes in contact with (valid meaning an object type that is erasable). Objects can be on any layer, or in a group, but they must be unlocked.
  • Objects that are not erased by the Eraser tool are: Images, Text, symbols, Graphs, and Gradient Meshes. The preview works on all objects, so it looks like these objects will erase, but on mouse up, they are not changed.
  • To erase Type, you can expand or create outlines first. To erase Symbols, you can expand or break link first. To erase Graphs, you can ungroup first. In all of these cases, the objects will no longer retain their type, symbol or graph attributes.
  • Some objects will erase, but their appearance changes due to rerendering of attributes applied to the object. For example when a brush stroked object is erased, it is broken into separate paths. The brush stroke is then reapplied to each path, which can drastically change its appearance. To erase a brush stroked object and not have it’s appearance change, choose Object>Expand Appearance first.

Eraser_Brush.jpg

  • When objects have an effect, like Roughen, applied to them, the effect will be reapplied to the new path created by erasing. This will look very different from the preview you see when you first drag the eraser over the object. In order to get the same results as the preview appearance, expand the appearance of your objects with Live Effects, like Roughen, applied.

 

Eraser_2.jpg

  • When objects have strokes applied to them and you do not want the stroke rendered for all edges of the new paths created by erasing, then expand the object first. If the object has multiple fills or strokes you will need to expand appearance first, then choose object>expand to expand the strokes.

 

Comments

  • By mutuelle - 11:36 PM on April 22, 2009  

    Thank you, informative post. But on the other side, the eraser tool can be extremely useful but sometime the limitations gives a result that is not so convincing.Anyway thank you for the info. Thanks, I’m glad this was useful to you. Hopefully you’ll be able to get those convincing results now that you know how to overcome the limitations.-=Brenda

    • By David Halley - 2:18 PM on May 2, 2013  

      Hello, and thanks for your explanations. I’m new to the Adobe software and what I’ve done, so far, is to import a drawing that I scanned as a jpg into Adobe Photoshop and erase the color of its background, then import the resulting drawing into Illustrator and apply Tracing, which produced an interesting image that I still want to change some things about, including fill in some lines that were in the original drawing but which were left out by the Tracing process. I’d also like to erase some small parts of the image produced by the Tracing process. While I’m in the Preview mode, with the mouse button held down, the erasing seems to be just as I’d like it. When I let up on the mouse button, the image returns to the previous state. Is there any way that I can have the erasure of the Traced object part be permanent?

  • By Xevi Olivé - 11:39 PM on April 22, 2009  

    I like it!Very clear.Thanks.

  • By Richard Gardner - 5:10 AM on April 23, 2009  

    That is excellent. Now that I understand how the thing works it will make much more sense of the way I will use it in future. Many thanks.

  • By mutuelle - 7:55 AM on August 20, 2009  

    i like it!very good articlethank you.

  • By Donna - 2:56 AM on July 30, 2010  

    When you state that the Erase Tool will only work on Objects, what is the difference between an objects and an image?

    • By Terry Hemphill - 4:40 PM on April 15, 2011  

      An “object” is a vector object created in Illustrator. An “image” is a raster image, a photograph or other raster image such as a TIFF or JPEG, that has been placed in Illustrator.

  • By anthony boberg - 4:18 PM on April 15, 2011  

    i was working on a project for class and i was trying to figure out how to make the font size of the eraser tool smaller and accidentally selected a a black stroke outline for the eraser tool. i cant figure out how to turn this off and the preference is staying on in every new file i make …. its rather frustrating.
    if you could please help me i would greatly appreciate it.

    • By Terry Hemphill - 4:37 PM on April 15, 2011  

      Anthony,

      The Eraser tool has no attributes, such as fill or stroke. The fill and stoke defaults attributes DO appear in the Control panel when you have the Eraser tool selected, but these are not applied by the Eraser tool when you work with it.
      However, if the object you are working on has an outline, then every pass through that object with the Eraser tool will also be outlined. So make sure that your object(s) have no outline before using the Eraser tool is that is the effect you’re looking for.

      If you’re still having strange results, you can always set your Illustrator preferences back to default. Instructions for doing so are here:
      http://help.adobe.com/en_US/Illustrator/14.0/WS714a382cdf7d304e7e07d0100196cbc5f-630ba.html#WS3C21A9BE-E974-4d42-9A73-167818925EE9

  • By AC - 11:14 PM on August 19, 2011  

    LIFESAVER! Object>Expand solved the problem I was having with lines losing their complexity! Thank you so much. :-)

  • By Matt Clarke - 6:31 AM on September 18, 2011  

    Thanks, this was really helpful!

  • By Josh E - 3:15 PM on September 27, 2011  

    Hi :) So, I have pressure sensitivity with my tablet for all the various brushes – however, when I use the Eraser tool, the “pressure”option is grayed out in the options box. Any ideas?

    • By Terry Hemphill - 12:27 PM on September 29, 2011  

      Josh,

      Which tablet are you using? Some tablets may not support an eraser. You may want to double-check with your tablet manufacturer as to what is supported.

      –Terry H.

  • By Kris - 9:47 AM on November 29, 2011  

    Does it erase text as well?

    • By Terry Hemphill - 9:51 AM on November 29, 2011  

      Hi Kris,

      The Eraser tool will not erase “live” text. Text has to be converted to outlines before it can be used with the Eraser tool.

  • By lori - 8:48 PM on January 13, 2012  

    I am new to illustrator. I have pasted a sqare pattern of a piece of fabric I like onto my page and want to erase 2 of the corners to fit a different shape I have drawn. The eraser wont let me, it says I need to expand the pict. I have but it still wont erase. Do you have any ideas?

    • By Terry Hemphill - 11:18 AM on January 15, 2012  

      Lori,

      You don’t say what format the image of the fabric is, but I’m guessing it’s a raster (photographic) image. One option is to use a Clipping Mask. For a very general overview of clipping masks, please see http://adobe.ly/zHAWS7

  • By Lukas - 12:58 AM on February 2, 2012  

    I’d love to see a snapshot of the appearance of the donuts. Is C after expanding A, and errasing or after expanding B that has been errased?

    • By Terry Hemphill - 8:41 AM on February 2, 2012  

      Hi Lukas,

      The result you see in C is what happens when you first expand the appearance of the original doughnut, then use the Eraser tool.
      Without first expanding the appearance of the doughnut, which has a Live Effect (roughen), using the Eraser tool will change the shape of the path that has the Live Effect, and therefore change the final appearance.

      Hope that helps,

      –Terry H,

  • By Bijutoha - 2:08 AM on May 14, 2012  

    Thanks it is very helpful , but i have a question , can’t i use Illustrator eraser tool like Photoshop eraser tool ?

    • By Terry Hemphill - 10:28 AM on May 14, 2012  

      Dear Bljutoha,

      If you keep in mind the diferences between Photoshop and Illustrator, one being an image editing software, working with pixels, the other a vector graphics software, working with mathematically defined paths, the Eraser tools in each software, while acting in similar ways visually, are performing very different actions. In Photoshop, the Eraser tool is changing the appearance of the image pixels, so the Eraser can have different options to affect this change, such as eraser types, e.g., airbrush, pencil, etc., and opacity options. In Illustrator, the Eraser tool is changing the fundamental structure of the objects that you’re erasing, and given the complexity of the objects that can be created using Illustrator, when using the tool, you must understand that you’re actually changing the structure of objects, not just the appearance.

      –Terry H.

  • By Bijutoha - 11:33 PM on May 18, 2012  

    Thanks Terry H for your good guiding information . i confused about illustrator eraser tool because some times i have felt to erase my object with low opacity in illustrator like photoshop but i never found any option to make that .

    I think might be any experienced designer will help me to give kind information about that and now i am so happy for your good information with good example .

    Thanks again Terry H.

  • By Sunny - 11:26 AM on June 9, 2012  

    Click on eraser tool. Choose eraser, knife or scissors. Place cursor over image and try to erase. Nothing. Try using keystrokes as well. Nothing.

    There is NOTHING, and I mean NOTHING that excuses the poor function of this program. Time after time after time. This is an example of a feature (one of many, many features) that should be brain dead point and click simple and yet it is not. It simply does not matter one iota whether we are talking pixels or vectors. It is the poorly designed interface logic that is the problem. THAT is solved by having people design the program that can think with the RIGHT logic and a leadership team that has the brains to lead them.

  • By Nitai Roy - 7:45 AM on March 18, 2013  

    It is really helpful. Is there any video tutorial for this task?
    On the other hand, Pathfinder of illustrator 8 is still good to me to separate parts of raster image. Do you think so? Though a lot of features has with illustrator 6.

    • By Terry Hemphill - 2:29 PM on March 18, 2013  

      Nital,

      There are many videos available online for this feature, just Google “Illustrator Eraser tool.”

      Best,

      –Terry H.

  • By Rameshkannan - 3:44 AM on July 5, 2013  

    I am using goocanvas widget for vector drawing application. and also I was stored Objects(Rectangle,ellipse,star,..) as path tag like inkscape. But I can’t able to get the data for path once eraser tool is applied.(we captured eraser path points and we concatenate with the previous tag for eraser tool).Is eraser function is right one what we mentioned above.(or) any other method for erasing the objects and storing methods?

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