Masking with AutoCAD Hatch

If you read CAD Notes tutorial on dynamic block, we use wipeout to automatically ‘trim’ objects. Very useful for placing door on a wall or schematic drawings.

However, wipeout has a downside. Some people reporting that wipeout won’t plot correctly on some plotters or to pdf format. I tried it, and don’t have any problem with wipeout. But if you have the problem, then what else can you use to do that trick? We can use solid hatch!

You can try to activate hatch, then select solid pattern. Then in color selection, you can choose the color to white. But where is the white color?

White color is not available in indexed color. Click the color list then choose select color.

hatch_color

Now you can see that default color is indexed color… and it has no white. But if you go to true color, you can find the white color. Move the luminance slider to the top or change the value to 100. You will get white or 255,255,255.

select_hatch_color

Now you can use it to mask object beneath your object.

Do you know that you can also have background color for hatch? This only available for pattern. You can mask object below your hatch, and show it more clearly.

hatch_background_color

If you still have problem with plotting hatch masking in pdf, you can see the explanation of ‘streak’ in here.

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  1. Clint says

    I too have had issues with wipeout plotting incorrectly in pdf files. Wipeout actually creates an image which blocks whatever is below it. There must be something in the way pdfs read that image that in my case creates a solid black object. My work around was to create a seperate layer to set my wipeouts on,0-wipeout and set the pen to 255 with screening set at 10, this results in an imperceptible gray that does not show in pdf and works well with our plotters. Just be careful not to set the layer to NP or freeze it, because then the wipeout will not show up at all and not block what was intended. I can see where thehatch may work better in some cases, since it will follow curves where as a wipeout only works with straight line segments. I find wipe out great for windows, doors and railings because I can hatch my surface and then place a block over it containing a wipeout and not have to wory about a gazillion islands in the hatch.