Graham The source code (mpost\therion.mp) contains some lines like this. def PenA = pencircle scaled (u/10) enddef; def PenB = pencircle scaled (0.7*u/10) enddef; def PenC = pencircle scaled (0.5*u/10) enddef; def PenD = pencircle scaled (0.35*u/10) enddef; def PenX = pencircle scaled (1.2*u/10) enddef; It looks suspiciously like the first multiplier relates to the intended line width in mm (at least for scales between 1:200 and 1:500). By default symbols are bigger for 1:100 and smaller for 1:1000 with corresponding adjustments in line width. I'm picking that if you enclose similar code in a layout ... code metapost endcode ... block, then you will be able to adjust the line widths. To make them twice as thick, change the /10 to /5 Let us know if it works. Bruce -----Original Message----- From: therion-bounces@speleo.sk [mailto:therion-bounces@speleo.sk] On Behalf Of Graham Mullan Sent: Monday, 1 April 2013 9:05 a.m. To: List for Therion users Subject: [Therion] Line widths in pdf Is it possible to control the line thicknesses in pdf files? When I export my pdf as an image file into publishing software, the lines are much too thin. I have played with scaling but it seems not to make much difference Graham