A blue line maching requires the master to be villum or some type of light paper so the lamp can get the light through. The plans are printed on 20 pound stock and it tends to make some very dark copies. The new type of scanning machines can be dialed in and give you A perfect copy. I was A printer and had the blue line machine and started to use Kinko's most of the time for that reason. Still good enough for cut up parts though.