Gripping, or trapping as it’s otherwise known, creates an overlap between butt-fitting layers which is an important step in finishing a design separation, so that when it is printed on the production press, no obvious gaps will show between the printed colours if there is a registration problem.

For quick and easy access, the Gripping function can be added to the toolbar of your Design Window.

Gripping solid layers to each other

1. Activate the first layer you want to grip, and make any layers you want to grip to visible.

A good general rule is to begin by gripping the lightest colour in the design to all other colours. If your company has specific gripping procedures, such as certain colours must grip to other particular colours, follow your procedures instead of this general rule.

2. Go to Window Menu > Gripping, or use the keyboard shortcut ⌘⇧G. The Gripping Window will open.

3. Select one of the gripping mode tabs at the top of the window.
4. Enter the number of pixels that you want to grip in the Amount field.
5. Choose whether to under grip or over grip. Under gripping contracts the design information, making a gap between the layers:

Over gripping expands the design information, creating an overlap between the layers:

6. ‘Only grip edges adjacent to other visible layers’ ensures that the active layer will only grip areas where it touches other visible layers. This should be switched on to give you full control of the grip, or off to grip to all colours in the design.
7. Click on the Grip button at the bottom of the window when you are happy with your settings.
8. Repeat the whole process for each layer in the design, gripping the next lightest colour next.

9. Grip to all relevant colours except those layers that have already been gripped.

Gripping tonal layers

There are several specific settings that need to be considered when gripping tonal layers.

• Reduce edges by - controls the size of the tonal steps between each pixel gripped so that a softer, faded grip can be achieved. This function acts differently with Standard and Circular / Rectangular mode. For example, if a design with a 100% tone edge is set to Reduce edges by 20%:

Using Circular / Rectangular mode, the edges reduce by the following percentages: 100% 80% 60% 40% 20%.

Using Standard mode, the edges reduce by the following percentages: 100% 80%, 63.92% 50.98%.

• Don’t reduce below - determines the minimum tonal value of the gripped edge
• Start Edge - lets you to specify the start edge tone of the grip
• Blur edges - tonally gripped edges can be blurred to smooth out the faded edges. Stepped effects can be avoided and the tonal fade can be made less noticeable.

It is important to note that blurring will change the tonal levels of the grip. For example, starting from a 100% edge and reducing edges by 20%, the third pixel out will not be exactly 51.2% in tone, as it would be if the edges were not blurred.

Texture gripping

Texture grip mode improves edges when gripping tonal layers. It works by copying the texture that is near to the edge, rather than extending the edge pixel. The edge pixel is frequently a low tone (possibly due to noise) which often results in unwanted castle or skyscraper effects when using other gripping methods.

The examples below illustrate this point. The image below shows the motif which needs to be gripped.

Motif as it appears before being gripped:

This image shows the skyscraper problem which results from a standard tonal grip.

Motif after being gripped using the Standard method:

Motif after being gripped using the Texture method:

Gripping texture layers

1. Select the layer and area to be gripped.
2. Click on the Texture tab in the Gripping Window.
3. Enter the number of pixels to use in the Overlap field. This will determine the tonal movement of your grip by specifying the number of pixels to be copied and blended from the edge of the information inwards.
4. Enter the amount by which you wish to grip your texture in the Amount field at the bottom of the window.
5. Repeat the process for other layers to be texture gripped.

Grip check: Checking gripped layers

Grip Check allows you to check the grips in your designs as part of your quality control process. It can be done on individual layers or several layers at one time. This feature works by checking a specified grip amount and then produces a layer indicating the areas that do not meet the grip specification.

In our example, the dark purple layer has been gripped to the light purple layer so that the effects are clearly visible.

Activate the layer which you want to check the grip against, ie a layer that was adjacent to the layer that was gripped and not the gripped layer itself. In this example we will activate the light purple layer. You can activate more than one layer if you need to. Just be aware that you must not activate the layer which had the grip applied to it.

Make the layers visible and select the Grip Check tab in the Gripping Window.

Specify the number of pixels or other unit to check for and click on Grip at the bottom of the window.  A new 1 bit layer will be created which shows any areas where the grip is less than the specified amount.

In the example below, the original grip was 6 pixels but during quality control, it was noticed that some of the gripping had been damaged in some last minute editing.  Therefore, to identify the over gripping areas which are no longer 6 pixels wide, a grip check of 6 pixels is used.

The new layer can be used like any other layer. Therefore, if the grip check reveals any areas which did not grip as required, they can be moved to the correct layer. This can be done with the Mover Tool, or copying and pasting from the grip check layer to the correct layer.

Automating the gripping process

Palettes are used to speed up many workflows throughout the AVA software. Our easy-to-use Multi Grip Task Palette Button is designed to make effortless work of the Gripping process, and using it is simple:

1. Go to our Downloads page and download the Functions Palette. This contains the Multi Grip Palette Button.
2. Open the design you need to grip.
3. Click the Multi Grip button.
4. Watch each layer of your design get gripped.