problems with yellow on komori spica 29p

Everytime I print, the 4th unit of my spica 29p gets completly dirty and the color yellow is never ok. It seems that all the ink on the blanket is going in the rollers.

 

Sounds like your inkers are old, either change out your ink train or reduce the tack of the yellow ink. The yellow will stay clean.
Old rollers instead of laying down ink will pick up everything on the yellow blanket turning the yellow unit usually green.

 

Check your fountain solution and Ink compatibility. Reduce the tack of the yellow.

 

You should use blanket with a roughness of 1.3 Ra or more. This is especially true for H-UV inks.

 

I would suggest that you be sure to not close down your ink fountains to zero. Even outside of the sheets perimeter you should be having a minimal amount of ink on the ink ball. If after allowing a bit of ink to flow across the entire ink ball you still get dirty yellow I would suggest that your yellow ink is too strong, or too tacky which is often one and the same. You can verify this by adding app. 10 to 15% of transparent white to your yellow ink, along with a bit of reducer. If doing this clears up your dirty yellow ink problems then you might want to consider talking to your ink supplier and requesting a yellow ink with a bit less pigment. This will allow you to run more ink through your fountain and should keep things cleaner.

 

it is necessary to reduce the dosage of water and the quantity of ink, to control the ph and the conductivity of the dampening solution, to make sure that the intermediate roller is well adjusted

 

Does anyone that’s recently commented realize that the OP was almost 8 years ago?
Hopefully they’re not still waiting for someone else to help them …

 

Perhaps the people that are offering solutions to an 8 year old thread are doing so to have it archived in order to help others with the same problem in the future. I know that was my intention.

 

Thanks.

Yes, while it can be confusing sometimes if an old thread gets bumped back up in the thread list, if someone encounters or solves the identical issue, or can share info that is on-point with an older thread, overall it's good to be able to add info. That way when someone searches in the future for the exact same problem, there is more information available.

 

I know that it s an old issue .
But we give more information for someone who searches solution to the same issue in the future.
He will find more details .
Good luck to all