Write-On has a "On Original" setting. You apply the first as "On Transparent", the consecutive ones on original. Of course, depending on what you do, additional pre-composing, channel effects and matting techniques may be necessary, regardless. You would have to clarify and provide screenshots.
Thanks for replying. I already tried that but it just leaves everything blank. I did the write on effects in a precomposition, could it be that this is wrong? I've managed to do it in the end with separate solid layers and using stroke. I think perhaps I need to go back and relearn write-on.
Thanks for your help
If I apply the effect a couple of times to the layer it either doesn't appear or only one effect will work.
you need to do this in separate layers, not separate effects. you are applying an effect that applies to the pixels of the layer on top of another instance of that effect that does this on top of the previous..
I have a kind of wireframe sketch that would be a bit difficult to split up into different layers
I would place the sketch at the bottom of the layer stack, and use the write on effect on different solids and set them to "on transparent". this way I will create different instances of my matte that draw's over my sketch. in the end I would pre-comp all these solids and set the sketch to use this pre-comp as an alpha matte.
I've managed to do it in the end with separate solid layers and using stroke.
stroke and write-on are different. write-on allows variable stroke through time and this is handy when you have different width of strokes or paths crossing each other. stroke allows stroke multiple path's simultaneously by unchecking the stroke sequentially option. if you need more control you should apply the stroke on different layers setting each to different path.
Impossible to determine the cause of your issues without seeing screenshots of the layer stack and the effect settings. Of course keeping everything on its own layer is always an alternative and who's going to argue if it works? ;-)