Back cylinder accumulating ink

I would like to have some feed back from you guys, i'm having a lot of ink that is accumulating on the back cylinder.

I'm running Reflecta from Hotsmann Steinberg for 5 years and never had any problems with other stock but on offset paper after 5000-7000 sheets this is how my backs looks like. Usually we don't print oftenly on offset but it happens more and more these days.

I had tried several fontain solution and another series of HS nothing help, do you have better result with open ink and today's paper ? Tired of cleaning that !

Any help and feed back would be great

 

I have seen this before, more than a few times. it's caused by ink not fully dry on stock. Usually on rush jobs. when you print the first side, try to put dryer in the ink and run ink lighter ( if possible ) Understandably printers tend to run the inks heavier on offset than coated, trying to get better quality.
at times I had been able to rid the problem by waxing and buffing the cylinder after I cleaned it. Other times I had found by having softer blankets (new ones) and backing off pressure as much as possible will eliminate the problem as well.

 

Thank you Bill,

You are 100% right about the punch we tried to had on offset, but that's what they ask for. I did run with an ink with more dryer in it, it was drying harder and faster but i didn't get a lot more of impression before i had to stop again and rub my back. It was set harder on the back too witch made the cleaning more painful and of course it was limit to dry overnight on the roller and the fontain.

Perhaps waxing the back coulds help, i had tried a paste povided by Hotsmann Steinberg but i don't remember the name of the brand, that help a bit but again the time i spend on applying it vs the time i gain on the run was so minimal that i only did it once. Maybe car wax is easyier and faster and the benefit are better?

Frank

 

Yes , I have tried auto wax myself, it does help more but eventually still had made it's way back on the cylinder. I had found that while trying to rush jobs it is best just to stop and wash the cylinder every so often as needed. I have found that rubber rejuvenator and a hard scrubbing pad works best at removing dried ink ( a lot faster than blanket wash ).
The smoother you can get your cylinder, normally , the longer you can print before washing.


I print rush jobs all the time, but I still don't like them. I only dream about one day with no rush orders.....

 

I have seen occasional success (complete when it happens) with changing the packing on Komoris to address back cylinder buildup. Not all Komori's come with the same packing recommendations and these recommendations are not always followed anyway. The surface speed of the plate and blanket surfaces and the relationship between the surface speed of the paper and the surface of the back cylinder are all affected by the packing heights and in the instances where this approach has worked the theory was packing changes reduced a speed difference between the paper and back cylinder surface, causing less friction, leading to less ink transfer. It is one explanation accomodating the well-recognized peculiarity of some Komori's suffering from this problem when most do not.

 

been there done that hate to say it but change your ink

FSA

 

Try spraying silicone on your back steel. Buff it down. This has always worked for me. Try printing on the back of the sheet 1st. All offset stocks have a smoother front side (felt side) that does not allow the ink to dry as fast as the rough side does. Bindery personnel will love you for it. Of course you must put paste driers in the ink do not use cobalt driers as they are for coated stocks only. The best solution is to let the job dry before you back it up. If it's going on the back steel, it's missing off the sheet. Also Reflecta is a coated stock ink not meant for uncoated paper. Cut your heat way back on your infrared and hot knives. You don't need all that heat as it dries out the absorbing properties of the paper.