Like many of you I too have received one of the excellent Rapido X31a box cars. The only modification needed is to change the reweigh date to a period within 48 months prior to the  end of 1950-54 period as the car is lettered for NEW 4-34. 

 

I am an SP modeler not a PRR modeler and the only set of PRR decals with PRR reweigh locations and later dates I have on hand is a National Scale Car (ex Speedwitch) D116 for X29 box cars. This should have the locations and dates that I want.  However there is a problem. NSC like other decal makers use the newer Microscale very pale light blue decal backing paper. I have tried all different lighting and angles and still am unable to read the smaller reweigh date information. I tried backlighting but the decal paper was too thick. 

 

I have tried using a black marker on the reverse side of decals in the past and only ruined the decal.

Has anyone tried scanning such decals and creating a negative image? What photo software settings did you use to create the negative image? I am currently using InfranView.