Fount

Fount is probably the single most problematic part of the press. If the performance suddenly falls or changes in any way then it's normally the fount that at fault. I will try to explain how to mix fount and how certain changes can affect the press and the methods used to ensure that the fount is accurate. It is important to keep the fount system clean from contamination. Any ink or paper dust that finds it's way into the fount has an effect on the chemistry and an effect on the quality of the fount mix. The press uses the Heidelberg Alcolor system and it is common on all Speedmasters. It is a five roller system that has the facility to run in integrated mode, where the press uses the ink as a carrier for the fount, and separated mode, where the fount is not introduced into the inking system.

Mixing Fount

Normally we use tap water to make the fount and it is important to establish what the state of that water is before we add the fount concentrate. During certain times of the year the water quality changes which affects the fount properties. The summer gives tap water a higher concentration of minerals whereas the autumn\winter\spring gives lower concentrations, due to the higher rain fall. The minerals are Iron, Calcium and Magnesium. Also, the chlorine added by water treatment plants can react with some compounds in the fountain solution and form hydrochloric acid. So first thing to do is to get yourself a conductivity meter and check the tap water. The meter puts an electric current through the liquid to measure the amount of dissolved minerals in it. The higher the reading the higher the concentration. The reading is given in Micro-Mho's (µMho's - which is Ohm, the unit of electric current spelt backwards).

We must establish the conductivity of water because that dictates the amount of fount concentrate that needs to be added to make the fount mix. If the overall mix has a conductivity that is too high then it will cause inking problems and if it's too low it will cause damping problems and foam in the tank. We aim for a figure of between 400/600µmho's for the final fresh mix. You must consider that alcohol has a conductivity of zero and so it dilutes the conductivity when added. Paper dust, ink particles and powder spray all raise the conductivity and after a while the fount will go out of it's usable range and you'll have to flush it out and fill it with new mix.

Generally, I mix the fount concentrate in at 3%. So I'll fill a 25 litre container with 800 floz of water and add 24 floz of fount concentrate. I use Vegra Blue 3300 because it has proved to be the most stable over the longest period of time with the best all round damping properties. Into that I'll add 120 floz of IPA and this gives a reading of ~700µmho's, pH of 4.5 and an IPA reading of 10%. As stated before, you will find that certain points of the year produce peculiar figures so it is worth checking your figures. The figures also change while the fount is used, firstly because the IPA in the system is set to 12% so the conductivity will fall initially, but also because evaporation and contamination affect the figures. For instance, after 250,000 impressions the figures read: 560µmho's. pH 5.1 and 12% IPA. The conductivity figures have dropped because the IPA has diluted the mix and the pH has risen due to contamination. Paper has a pH around 7 so the more paper fibres that get into the fount the closer to seven it becomes.

Potential Problems

As stated above, the pH of the mix should be around 4.5. You will find that most people advise pH 5.5 but I have found that better results can be achieved with 4.5. Again, it is a property of old, used fount that the pH is higher than the fresh mix. If the fount has been in the system for over a million impressions then you begin to invite problems with the print. Higher pH will cause problems with drying, inking and damping. It's important that you are aware of the potential pit falls of poor house keeping and the dangers you face and weigh up if it's worth changing it or not.

pH Chart

Look For Clues

When you first mix the fount and add it to the machine it's at the correct pH, conductivity, IPA concentration and temperature. As you start to use it the fount picks up debris from the press such as paper fibres and ink particles and all of these cause problems with the conductivity. These are filtered out of the fount by the filter bags but it stays in the system. The pH should remain fairly constant because most founts use buffering salts to keep it that way, although the salts do form another compound in the solution to achieve it. Eventually the salt supply runs out and the pH will rise. Another problem is evaporation. Once the press is up to speed the heat generated causes the IPA and water to evaporate from the fount. The IPA metering will correct the level of IPA but the evaporated water cannot be corrected without a dosing unit.

When the water evaporates it does so in a pure water form and so the minerals that are present in hard water stay in the fount system. These minerals will collect and cause conductivity problems. When you consider that the press can use around 15 litres of fount in an eight-hour shift it doesn't take too long before the carefully mixed fount is way off the mark. The IPA metering device is basically a conductivity meter. IPA has a zero conductivity and so the when added to the fount mix it lowers the conductivity. This is how the IPA metering is calculated. When the conductivity rises above a set value the system adds IPA to dilute it until that value is reached again.

What this means is when the minerals from the evaporated water collect in the reservoir they will cause the conductivity to rise and then the IPA system will start to add IPA, not because it needs it but because the conductivity is rising. So your fist sign that the fount is going out of range is when it starts to use more IPA than normal, and starts to smell. Eventually the system will enter a struggle between the IPA and minerals. Another clue is that you will have to lower the metering levels on the press. The rise in IPA will cause the fount to become very efficient and you will have to lower the level to compensate for the increased dampening. In the end the fount solution will give up and will need to be cleaned out and fresh mix added.

Remember that litho is a controlled chemical process and it's the fount that we have control over. The ink is pre-mixed and is out of our control. If in doubt, suspect the fount!

Damper Set-Up

Key 1. Damping form roller, rubber 2. Intermediate roller, rilsan ('Z' roller) 3. Water pan roller, rubber 4. Metering roller, chrome 5. Ink form roller, rubber FR. Fixed distributor, chrome

The damping system is very stable and doesn't require regular maintenance. You can safely de-mount all the rollers and refit them without altering the settings. However, that doesn't help you if something is going wrong. The first signs of a setting going out can be detected in the print or on the plate. The press should distribute an even film of fount to the plate but if that goes out for any reason it will cause problems. If one side of the plate consistently builds up ink then it's fair to suspect the film of fount is thin on that side. If it is difficult to get the correct ink density on one side of the plate then it could be that too much fount is being offered to the plate and denying the ink from being accepted by the image. I say usually because there are other possibilities, such as the rollers still being wet from a wash-up. The set-up for the damping system is as the manual and is good and easy to follow except where water pan roller to chrome metering roller are concerned.

This is the most difficult roller pressure to set up on the press as it has a roll on action so the bead line is not always accurate or easy to read. Almost every minder has a different way of setting this pressure, ask around and chose the best method for yourself, below is my way. The Heidelberg Alcolor system is temperamental with it's set up, however, when set up it's almost faultless.

To set the moisture metering roller pressure to the moisture form roller
Rotate the plate cylinder so that the plate clamp is towards the delivery end of the press. Set the pan roller to metering roller by backing off the pressure so there is an ever flood area on the ends of the rollers of around two inches, then go on until the flood area disappears, keeping the pressure even. Final adjustments are made on the run by adding five minutes to the side that scum's first or is troublesome.

Next, back off the metering roller to form roller pressure two whole turns (anti-clockwise) and insert two thin strips of paper into each end of the gap, one slightly wider, say two inches, against the form roller and one thinner strip, say one inch, against the dried off metering roller. Engage the dampers so that the moisture form is in contact with the plate (this is why you must rotate the gap in the cylinders to the front), then adjust the pressure so that the resistance on the thinner strip is even, slight but positive (lighter than you would set an AM 1250/1860). Once set turn the pressure on two whole turns.

You can set the metering to form pressure using a compression stripe but that isn't always reliable because of the roll on compression action of the rollers. If you do, the stripe that is important is the centre two of the four lines, normally the darkest. If you get a good reading, and it varies from press to press, set the bead line to 4mm. Some other methods I've come across are to back off the roller pressure two whole turns and then use a feeler gauge between the rollers, another is to run a dry solid and then apply the dampening rollers and the plate should start to clear in three revolutions from the centre out, applying a slight turn of five minutes the side that clears last until it evenly clears from the centre out.

General Set-up

The refrigerator unit should be set at 10°C. IPA evaporates at around 15°C so it is essential that the fount is cooled to below that figure to maintain 10% IPA concentration and prevent excessive airborne solvent concentration. However, once the thermostat is set it should never need re-setting. The solenoid on the IPA metering device becomes blocked with calcium due to a design fault with the unit. When the system is shut down at night, fount is sucked up into the solenoid through capillary action. Once in the solenoid the calcium will deposit in the pipes, eventually blocking the flow of IPA. It is easy to detect whether this has happened by looking at the level of IPA in the bottle when the system is trying to meter IPA into the fount and look if the level drops. If it does not then the solenoid is blocked. To clean it out will require removing the back panel of the refrigerator to get access to the solenoid. If you look at the solenoid you will see a large nut on top, undo this nut and remove the magnet, spring and stopper. You will see that the base of the solenoid has two holes, one where the IPA enters and the other where it leaves. It's the hole that is off centre that becomes blocked and needs blowing out with the air line. Once cleared out refit the plunger, spring and nut and the system should work properly.

Terms explained

pH - A pH reading is a measurement of the concentration of hydrogen ions present. A neutral solution contains an equal amount of hydrogen and hydrogen ions. The pH scale, 1-14 is logarithmic, i.e., pH 2 is ten times more alkaline than pH 1.

Conductivity - Conductivity is the ability for a substance to conduct an electrical current. The degree of conductivity is determined by the number of ions present, based on the amount of minerals and other compounds in the solution. A higher concentration of ions will allow for higher conductivity. In most cases water has a very low ion level which results in a very low conductivity reading. We use the conductivity reading to determine the amount of fount solution that is to be added.

IPA - Isopronal Alcohol. We use IPA in the fount to reduce the amount of surface tension and allow a lower level of fount to be used. Using less fount reduces the effect of printing on the paper. Reducing the temperature has the same effect.

Reverse Osmosis
The way around problems with the fount mixing is to ensure that each and every time you mix fresh fount it is to the exact same specifications. As I've already said, the tap water varies so companies have to look at getting around using raw tap water in their fount mix. The answer is reverse osmosis. This is a filter box that is plumbed into the mains water and produces de-ionised water. The unit has a very fine membrane that the impurities cannot get through. However, the water produced is too soft to use for fount so it needs to be hardened again. The benefits of this is that you know the exact starting point so you can add the correct amount of hardener to get the water back to a suitable point for the fount mix. It takes the tap water variable out of the system. This process is generally used in large printing companies but it's useful to know. It has been said, however, that the hardening agent is very harsh and can also cause printing problems.

Summing up

I hope this outlines that fount, and printing in general, isn't a random set of circumstances. You will encounter problems if you do not follow the rules. There is a narrow range where any press will perform at it's best, if you stay within that you will produce more work of higher quality. 'Everyone mixes their own kind of fount' is an ignorant thing to say. You may favour a different manufacturer but the fount mix still has to follow the same set of rules. Having a bad style of mixing fount ('some of that, bit more of that' kind of thing) is also bad practice. It is impossible to aim for optimum results or work at your best if your chemistry is randomly made.