Fading\blinding in first unit only

[RGPW17100]

It may have been mentioned but not sure. Are you running alcohol or alcohol sub? We run a Speedmaster and run about the same amount of sheets you do. Our tank holds about 10 gallons. On a short production week we will change out water every two weeks on heavy production weeks especially when running uncoated ( seems higher in calcium) we will change out water every week. We run alcohol so flushing the entire system is not needed as often as the alcohol acts as a sterilizer and cleaner. We manually add alcohol to the system using the conductance meter as our guide. Normal for our solution is around 1200-1400 umhos. When it exceeds that we add more alcohol to keep it in that range. Hot days will tend to burn more alcohol. Press runs hotter and the alcohol evaporates faster. With all this said it does not make sense only one unit is the problem. We typically see the cyan unit plate go bad first on longer runs and see toning on the magenta when water is contaminated. If you soloution is as dark as you mentioned either you have a super tight budget on chemicals or your press operator is lazy. Lazy people work a lot harder then people that are meticulous.

 

[Cornishpastythighs]

CD102 has a good point, looks like your press people are calling the shots and to be honest from what you have said so far they are ill equipped. Fountain solution starts off nice and clean and usually looks the same colour as the etch. Alcohol sub is usually clear. This is with a 2 part solution. During the course of the day it will become contaminated with ink residue, roller wash, metering roller wash, paper and even spray powder. All these chemicals do not make for good fountain solution so we monitor the condition using simple tools pH sticks, Conductivity meters, Refractometers to maintain our fountain solution efficiency. As a company you have to decide when it is the right time to change your solution by monitoring your quality Dot gain, Trap etc. Hopefully someone can educate your pressmen.
Good luck

 

[Cornishpastythighs]

RGPW We used to run Alcohol but could not use a Conductivity meter to check it as Alcohol has no conductivity so we had to use a wet/dry bulb Hydrometer to check the %.
We now use a Refractometer to check the Alcohol sub

 

[Prepper]

Great info RPGW and all, yes we are running alcohol, it is metered in automatically. No it doesn't make sense to be the first unit only as the first 4 units are all on that same solution and the other 3 plates are lasting 125,000 over 3-4 days of cleanups and restarts without any problems. We don't run any uncoated, all 100# or 80# gloss.

Adding alcohol is just lowering your conductivity reading because it has a 0 conductivity right? But by changing every week or 2 you are keeping it clean. Yes, ours was dark, I'd say a pretty dark gray, about an 80% tint. And cloudy enough you couldn't see anything thru it and that was looking at about 2" in a glass. I suspect it may have been more than 2 weeks since it was dumped and mixed fresh. I'll see if I can find out.

 

[Alois Senefelder]

Fountain Solutions Again !

Fountain Solutions Again !

Hello Cornish, RGPW and Prepper,

Comment - hopefully you are running the F.S. Chilled? 10/12 deg. Celsuis and
circulated through a filtration system.

Using Alcohol Free Concentrates, crucial that they are cooled, this is because the
F.S. have a low viscosity. Lowering the temperature increases the viscosity thus
helping Fluid Transportation through the dampening roller system.

Water at 20 deg. Celsuis = 1Poise
**** 10 deg. Celsuis = 1.3 Poise


Regards, Alois

 

[Cornishpastythighs]

Cold enough to keep my Fosters lager chilly

 

[RGPW17100]

Great info RPGW and all, yes we are running alcohol, it is metered in automatically. No it doesn't make sense to be the first unit only as the first 4 units are all on that same solution and the other 3 plates are lasting 125,000 over 3-4 days of cleanups and restarts without any problems. We don't run any uncoated, all 100# or 80# gloss.

Adding alcohol is just lowering your conductivity reading because it has a 0 conductivity right? But by changing every week or 2 you are keeping it clean. Yes, ours was dark, I'd say a pretty dark gray, about an 80% tint. And cloudy enough you couldn't see anything thru it and that was looking at about 2" in a glass. I suspect it may have been more than 2 weeks since it was dumped and mixed fresh. I'll see if I can find out.

Yes we add the alcohol to lower the conductance because the alcohol has zero conductance. We had the nice hydrometer but it broke but we got used to seeing the effects on the conductance meter to know when the amount of alcohol was going down. The cheap alcohol tester with the floating balls was worthless. Seems to me alcohol percentage also depends on fountain temp so a standard cheap tester gave in accurate results. We were going to replace it but management keeps threatening to go alcohol free but has not done it yet. When we mix fountain without alcohol our conductance is around 1500 umhos or micro seimans which ever you prefer. We add to 7 percent alcohol by volume and the conductance will drop to around 1200 umhos. This becomes our guidance number on how much alcohol we need. As the week progresses and the water gets dirty these numbers will go up. When the number goes over 1800 umhos it is usually time to change the fountain. Our conditions are pretty primitive but we get the work done. Good luck with the blinding issues. We are using the same plates as you but we seldom go over 50000 runs on our machine

 

[blazini]

I think we're kind of off base on what conductivity actually is. Conductivity in and of itself really doesn't mean anything, it's just a measurement of dissolved solids. It's just a gauge to measure how much of your fountain solution is not water. If you are starting with RO water you dose the etch to match mfr specs and you should come out at close to conductivity specs and adjust accordingly. Now once you put that solution in the press and run it you can only use conductivity to measure how "dirty" the solution has gotten. You can dump a bottle of blanket wash in a tank of water and the conductivity will shoot up, but that doesn't mean there's etch in there. I've never used alcohol, but alcohol subs were always dosed by volume

I would never use water or alcohol to regulate conductivity one the fountain solution was in the press, you have no what is in the tank when you do. I suggest you only add mixed solution to the press tanks, and top them off when needed. If there is a problem and conductivity is high the tanks should be dumped and refilled with fresh mix. High conductivity means that the solution is getting dirty faster than it's getting used. Not sure how you're set up but you should make it as easy as possible to dump your tanks. Opening a valve to a pneumatic drain pump is far less time consuming than draining it into a barrel and hauling it off. If you want to extend the life of the solution you should install a filter system. A filter canister at each unit and a filter on the press return at the tank will work wonders for keeping the emulsified ink out of the solution.

Hitting the plates with the dampener at the end of the day is also bad practice AFAIC. Plates oxidize once they get wet there's not nearly enough gum in the fountain solution to keep this from happening overnight, especially when the solution is all nasty. Usually this sensitizes plates rather than blinds them but anything is possible. They should be hitting the plates with diluted plate storage gum or even plate cleaner or scratch remover as they contain alot of gum.

Also, coldset, Heatset or UV, I've never seen a good 2-part etch. Standalone alcohol subs have caused me nothing but trouble. Everything that has worked well for me was 1-part as it contains the wetting agents and everything all in one bottle.