GTO Fount Observation

[UKPrintMan]

Hi to all

We have just got a second hand Heidelberg GTO Alcolor and i noticed that there are calcium deposits on a leaky part of the re-circulation unit and that the rollers are glazed. With my limited knowledge of chemicals (which i want to improve), I am currently guessing that the previous owner may have been running it with a fount solution with a high water hardness. With that in mind, do you think i am correct in saying this as i want to try and minimise roller glaze?

Also what fount do you find gives best results for a GTO?

Jamie

Edited by: Jamie on Feb 23, 2008 1:38 PM

 

[Paultheprinter]

Re: GTO Fount Observation

Hi jamie

Firstly you mention calcium deposits on the recirculation unit and attributing this to a high mineral content of the fount soloution, the difference in mineral content between the softest <120PPM to the hardest >300PPM would not be noticable if the two were side by side, the contributing factors would be time allowed to leak e.g month/year volume, drip once a day/ once an hour. "I am currently guessing that the previous owner may have been running it with a fount solution with a high water hardness", Fount soloutions are designed to work wiithin a certain water hardness and are not designed to re harden water. The previous owner may have ran a fount soloution to cope with a hard water but not a fount with hard water. You are correct in trying to reduce roller glaze as you want the inkers and dampers to transfer ink and water as effectivley as possible, this may only be possible by regular de calcifying and de glazing as most of the glaze will come from ink,fount or paper.
As for the best fount to use on GTO, it deppends on what plates,ink blanket, paper and type of work you do. Try a few and note down average water levels, any problems and how soon you need to flush system. Try long runs and see if emulsification is an issue. The more you try the more you will learn.

Paul

P.s ive seen gtos run with 10% IPA and no fount and they ran ok, not that im suggesting doing it.

 

[UKPrintMan]

Re: GTO Fount Observation

Thanks for a quick reply,

That helps a lot, as i have never had any training is this stuff your answer helps me work out what's best, I had the feeling it would not be a straight forward answer due to multiple factors I didnt factor the other items contributing to glaze so a regular deglaze will continue, time to start a testing routine. Did some mixing and going by the tests and engineer recomendation my first test is going to be 4% fount (to give 20-50ppm hardness) 10% alcohol (for a thin film) 86% water. I get the feeling i will have many more questions, lol.

Cheers

Jamie

 

[Paultheprinter]

Re: GTO Fount Observation

Hi Jamie,

Nice to see you trying some mixes, ask your plate rep or chemist to suggest a conductivity value for you to achieve with the consumables you use. I only use PPM to look at incoming water quality as i know how it relates to german degrease, on my conductivity meter with its conversion factor its exaxtly half of the conductivity. e.g 150PPM = 300 Micro seimens.
With 3% fount our incoming water (160-200MS) gives about 1500 Ms and with 8% IPA were down to 1000Ms PH 5.0 This works ok for us any less eg 2% i get hickeys, piling and any more 4% i get washing out and emulsification. Ask as many questions as you need to understand the ins and outs, I spent three years doing a nvq level 3 and it taught me how to reference a folder and nothing about printing.

Just to note in my area (West Midlands) the tap water is aprox 300ms to 500ms or 150-250PPM Most people may argue that 150 ms (75ppm) is to soft, and there correct but i saves us a lot of decalcifying without any downsides so far.

Edited by: Paul Green on Feb 24, 2008 9:25 AM

 

[aprovost]

Re: GTO Fount Observation

Hello Jamie,
I have read your question and agree with Paul that you have some significant issues to deal with.
My suggestion would be to bleach the entire water system and rinse very well with water. Then clean out all the water pans and start fresh with new fountain solution. As for the glazed rollers, depending on the severity of the glaze and the overall condition of the roller including durometer I would suggest the following. Take out each roller in you ink train and scrub them down with a very fine pumice and water mix and clean off until rubber appears to have a velvety look. Reinstall rollers in press making sure that all nips points are perfect. Use opaque white to check nip points, it is much easier to see ink settings with this color. I would certainly suggest using RO water from this point on but if you do not have the means to do this then please do the following from this point on. Beginning with every wash up of your rollers you must use hot water to rinse out the surfactants that may still be imbedded in the pores of the rubber. The hot water will be used during and at the final rinse. I would recommend a product call Febo Clean 2000 and Calcium Fix that both come from Bottcher roller corp. Use the two products exactly as directed and believe me you will see a big difference in your press performance. Good Luck.
Al

 

[UKPrintMan]

Re: GTO Fount Observation

Hi,

I finally got a chance to run it for the first time after a quick lesson from another gto printer. Very nice to run compared to a multilith! a breath of fresh air, although I have found my first mix (4% fount 10%alcohol) to be too acidic as the ink is not drying that quick, so will be upping the ph a bit. I need to get my boss man to buy some better measuring devices before I can get the results I want though. Al I will do what you suggested with regards to cleaning except the bleaching as I feel a little nervous about that, as I dont want to contaminate the system in a different way and cause down time. The guys have put a large workload on it already so the major clean will have to wait for a bit

Cheers
Jamie

 

[Paultheprinter]

Re: GTO Fount Observation

Hi Jamie,

If you drop to 2-3% fount concentration your PH should rise and as you say will help with the drying issues. as for bleaching the system, i thing Al means flushing with a cleaner. Litho supplies do a dampening system cleaner which can be watered down and mixed up and left overnight to remove any algi or crud in the pipes. Its very caustic and the system will need "shocking" with a strong fount mix untill all the alkalines are neutralised. You will need to run at least two strong mixed through for 10 mins a time and maby a few water only flushes to ensure this. If you do this ensure that your down to Ph beforeyou startup as if you dont the plates will catching up untill the gum stops desensitising the non image areas.

Paul