The TrapType property controls, through a value of PrnTrapType, the opacity of a trap.
Examples:
The following VBA example specifies each trap layer as transparent.
Sub Test()
Dim intCounter As Integer
With ActiveDocument.PrintSettings.Trapping.Layers
For intCounter = 1 To .Count - 1
.Item(intCounter).TrapType = prnLayerTransparent
Next intCounter
End With
End Sub