Magenta blinding on silvermaster - stumped

[CostaRicaPrinter]

Hello fellows,

I'm new to the forum, and I see lots of good discussions! Thanks to everyone who shares their knowledge and experience.

I have a small book publishing operation in Costa Rica. We recently brought in a Printware silvermaster platesetter, and have just loved it (we were using plastic laser plates or metal plates and negatives before). HOWEVER - when doing 4 color work, we have had consistent problems with magenta plugging up fine screens, and drying out on the plate.

Our press is an AB Dick Century 3000, motorized dampening, alcohol system. We are using Kerley ink, but have tried other inks as well. We have a plethora of fountain solutions - with and without alcohol, and have tried them all. The best we can manage is with Baseline Pink and alcohol - but we do around 1,000 sheets and the plate starts drying out and the screens plug up.

I've read some posts, and I see that magenta often presents a problem, especially with the black plates. Any advice will be well received!

[Cold]

Before taking any further steps, I strongly recommend de-calcifying your roller train.

[CostaRicaPrinter]

Hello Cold,

We did a deep clean - actually several times. We use Bottcher cleaner, and used vinagre with warm water. We don't have ANY problem with any other ink - the press prints really well. But since we've gone to the silvermaster plates, magenta gives us a headache.

Thanks!

CRP

[Bob Peterson]

It sounds to me like you are emulsifying the magenta. Try using a magenta with a heavy body, in a pinch you might try adding 10% of a heavy binding varnish.

[Cold]

Ok, if you are confident calcium is not a factor, I suggest:

Let's eliminate the unit, switch the cyan and magenta units for a job(s) that can stand the trap difference. Does the problem follow the magenta?

[Richard]

Hi: after looking at a century 3000, it looks very similar to the 9985 I currently operate.
And I have to admit, I encountered exactly what you describe. Except I was doing a two color job: black and magenta. The magenta image was finely screened. It was the image of a machine part, and was supposed to look shiny, in magenta, after 20,000 shts. I found that the magenta is very soft. I set the ink fountain low, evan off at some points in the run. I reduced the blanket to impression pressure, maybe even at the lowest it would go. And, there is a good chance I removed one of the three ink form rollers. Yes, you can remove the biggest one without a problem. This is why your screen is plugging in. Two ink form rollers may be all you need. Pull the third form out. Just open the gate, open the op. side panel, and try it without it.

richard.

[Richard]

Hi: after looking at a century 3000, it looks very similar to the 9985 I currently operate.
And I have to admit, I encountered exactly what you describe. Except I was doing a two color job: black and magenta. The magenta image was finely screened. It was the image of a machine part, and was supposed to look shiny, in magenta, after 20,000 shts. I found that the magenta is very soft. I set the ink fountain low, evan off at some points in the run. I reduced the blanket to impression pressure, maybe even at the lowest it would go. And, there is a good chance I removed one of the three ink form rollers. Yes, you can remove the biggest one without a problem. This is why your screen is plugging in. Two ink form rollers may be all you need. Pull the third form out. Just open the gate, open the op. side panel, and try it without it.

richard.

[CostaRicaPrinter]

Hello Cold - yes, the problem follows the magenta. We have an ink - solution - plate issue.

Richard - our problems are with fine screens also. Why do you think that using less rollers helps the problem? We did reduce blanket pressure, and helped a bit.

Bob - we actually found that REDUCING the body of the ink helped. We have a pretty cool environment (air conditioning), so heat is not an issue. When we softened the ink, we could at least get through the run (after cleaning the plate a few times).

I spoke with our supplier of the silvermaster plates, and he recommended a product by Allied called DTA. Anybody ever use it? It is supposed to help with wetting.

Thanks fellas! I think I'm making progress at least in understanding the problem http://printplanet.com/forums/images/icons/icon12.gif

CRP

[RGPW17100]

We used to have the same problem. Our ink company put a varnish in to help fight the water. In a pinch you could use Rubine red instead. It is a bit stronger then Magenta but may be a stiffer ink.

[Asures]

With regard to Polyester plates, they have always been a challenge.

The problem that you are having is that on the polyester plate in particular, there is no actual grain for the non-image area to effectively carry an even film of water. It is actualy a silica coating that yes, carries water...but not very well. Rather frustrating to us ink guys - actually!!

As a result, once you start running, that non-image area water is being absorbed into the stock and you end up running too dry - hence screens start plugging, and you see scumming on the lead edge of the plate (that everyine calls "Toning"). You run your water up to keep the screens clean and before you know it, it has whacked your ink by over emulsifying the color giving problems.

There is actually a product that can help made by Silvermaster. It is called "Silvermaster SLM-Ao2" that is designed to be added to any fountain solution. It helps by allowing your fountain solution to bond to the non image area of the plate and carry water evenly. That is where Allied DTA came from but was recently discontinued due to the short shelf life. SLM-Ao2 will keep your screens clean and eliminate a good majority of the problems you are describing. Take a look at the link and info below.

Mitsubishi Imaging (MPM), Inc. - Graphic Arts

You can talk to your supplier and specifically order that product. Do not be alarmed by the foam that it creates once added.

Good luck to you.