2 sides printing need help

Hi, I'm using SM74 Heidelberg 2 color machine. When I print one side of CM and I need to turn to print the other side, why is it that without any changes I made, but the density/ color settings changes by itself? Appreciate every suggestions.

 

Paper has two different sides when it is made, it has the chrome side and the felt side. Using your loop you can see the difference, and it will print different. Having said that the better the quality stock is made using chrome on top and bottom, but that is the better quality sheet.
FSA

 

how about the machine settings? actually, there are way too many factors in printing a good sheet.

 

Well lets see, how old is the press? Are some of the ink zones buttons sticking? Then there is compensation curves, but you have to change them, and they can affect the print with a change in speed, but I wouldn't blame them. How much time went by from one side to the other, ink tacs up and that can make the print look different. Is this a problem on all stocks and jobs or just sometimes. Do you clean the blankets before you print each side? Will your densitomitor give you the same number if you were to read the same colour bar 5 times, if not it needs to be recalibrated. Are you running with alcohol? Is there a growth of slime in the main water tank? And finally how old are the rollers? Answer those question and we'll try and help you.
FSA