CD wrote:
Cmohr, what's the best way to clean the dampener covers. I was doing it with cold water but I now think hot would be best.
There are a lot of different opionions about that, I find for me, big sink, get a jet nossel on the end of a hose, and blast them clean just with water alone (no cleaners), hold the roller at one end and sit the bearing at the other end in the sink so as the roller can freely spin, use the water jet at an angle so as it spins the roller around, and run the jet up and down the roller, you should see all the ink coming off it and it coming clean, then I ussually just keep the jet at one end so it spins the roller real fast and that works like a spin drier and flicks all the rest of the water out.
I used to do the whole put dampener cleaner in and srubb with a brush, but, i found that that just rubbed ink further in and left the dampener contaminated with the cleaners and old ink, that can cause heaps of problems printing, like tinting in non-image areas and ink imulsifing causing poor images and solids. Make sure you keep your fountain solution clean, always wet the dampeners with fountain solution before putting them in , don't start up the rollers dry and get ink on them, if you always use fountain solution, it will help the cover to repell the ink. Then, when cleaning with the high pressure plain water jet the ink just comes out and the roller comes back to white (or red or blue depending on brand) very and easily.. If your dampener rollers don't have exposed bearing at each end for you to rest them on, it may be that they are held in the machine by a rod that you insest thru the side of the press, thru the roller and into the other side of the press, if thats the case, just thread the bar back thru the roller after you take it out of the press, that will give you something for it to spin on and something for you to hold on to whilst using the water jet. I always found the better and faster the roller spun whilst I was washing it, the cleaner and better the roller would be. Then after I had finished cleaning the roller, and I was shutting down for the night, I would spray the cover with a little straight fountain solution to wet the cover again, then scrap off the excess with a blunt edge (nothing sharp) that would then dry into the dampener cover once again making it better repell ink later.
If you look at the cover you will see the nap falls in only one direction, only ever scape the roller in the direction of the nap, if yu go against it you can cut and damage the cover and reduce its life and effectiveness. I think you have 2 wetting rollers and 1 ductor roller in that system, when you install them into the machine make sure the naps fall in alternating directions, IE if the ductor roller falls towards the operator side make sure the 1st wetting roller falls towards the off side, and then the 2nd wetting roller back towards the operator again, the water flows in the direction of the nap as the machine spins, and if all are facing the same direction, you'll find it hard to get an even water flow, you'll be washing out on one side and getting scumming on the other. Also make sur eyou regularly adjust the dampener pressures and keep them even, standard sort of presures (3-5mm bead, or if setting with strips moderate- even pressure both sides) uneven pressures willl again result in water travelling to one side or the other, scumming or washing out.
Hope that kinda makes sense.
cmohr
Oh and COLD water works a treat. Only ever use hot (or even boiling water) when you first shrink the covers on, after that, cold is all you need.