I just started operating a 02' komori 28 lithrone. The chrome roll is picking up ink when running pms reds but not magenta.After wash up they apply an etch solution to the roll. The shop uses Four Star fountain solution 2.5 oz. and hydro plus alcohol sub 12oz. and 2 oz of Allied dryer per 5 gals of water. Any advice would be helpfull. Thanks

Sensitizing often occurs when the hydrophilic layer on the chrome is broken down in some way Are the inks you having the issue with, by the same manufacturer as the standard cmyk set? Are they vegetable oil, petroleum or rubber based? Are the recirculator and water pans clean? Do you have infra-red dryer? If so why do need to put additional dryers in the fount? Is this a new problem or a recurring one?

By etch - do you mean gum arabic? Normal action we would take assuming all the above check out OK.

1 apply gum arabic after every shift - leave overnight
2 if you still get ink picking up - try mrc or equivalent (metering roller cleaner) directly to the chrome - apply gum and leave to dry

If you still get this issue you may need to change ink or fount. We get great results from VARN products but you need to check the quality of your incoming water supply.

Have you checked ph and conductivity of the fount solution?

Hope this helps...