Wallpaper Border removal/painting advice please

I have a wallpaper border in one of my rooms. I have tried to remove it but it is getting virtually impossible. Now a few weeks ago i was watching one of those changing rooms type of programs and the guy had the same problem. To get around this he use some sort of paste which he spread over the border to cover it. So when he came to paint the walls you coulsn't see that there was a border there. Any ideas what he used? or anything similar that could do the job.
many thanks.
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