Necessity of p.H in offset

[Yuvaraju.V.]

Hey everyone,
What is the necessity of p.H in fount solution for offset printing? Why it should be at 4.5 to 5.5 why not at neutral 7.0.
Is it just because to have proper emulsification or something else is left out.
Can anyone brief me on it?

[Cornishpastythighs]

Yuvaraju
Two important key properties are fountain pH and conductivity. What is pH? Well in the Roman days they knew it as "potentia hydrogenii" or "potential for Hydrogen" thus the small "p" and capital "H." Ph is a measurement of the degree of acidity or alkalinity of substances. Ph is important for maintaining high-quality, trouble free printing. The purpose of the acid in fountain solution ensures that the action of the gum is reinforced and not destroyed. An acid such as phosphoric or citric in a sufficiently dilute form will, in combination with the gum arabic, liberate the arabic acid molecules from the gum and permit them to combine with the metal oxides (aluminum) on the plate. This results in the desired hydrophilic (water loving) surface of the non-image areas. This breaks down quickly but is reinforced every time the plate has the fountain solution reapplied (every turn of the plate cylinder). To keep the pH stable, as contaminates such as Calcium Carbonate, attempt to change the solution pH, buffering agents are added. These keep the pH stable during the course of printing.

Taken out of a technical manual

[aqazi81]

Whats the ideal conductivity for ALCOLOR dampening system?

[RGPW17100]

Ideal conductance for alcolor will depend on your fountain solutions requirements. Using Alcohol or the use of alcohol sub will make this vary. If one printer is using Fuji Hunt and another is using Anchor fountain the targeted conductance will vary.

On the PH issue is PH an issue when using Poly plates? My understanding is no due to the wetting is done by glycerin instead of acid.