PUB: Hairlines Disappear When Printing to an HP III

When you print a publication, certain lines disappear randomly from a document printed to a Hewlett-Packard (HP) III series printer at 300 dpi. The lines that disappear are the lines set to the Hairline thickness, to a color other than black, and to the lightest gray fill style.

The HP III printer trys to fit the pattern fill of the light gray style to a 300 dpi grid using an averaging algorithm. Some pixels fall out of the average, others find a perfect match. The color black fills the pixels evenly, while the other colors have an uneven fill pattern that doesn't quite match the average.

There are four possible workarounds:

• Change the width of the line to one point. This will create a line that is four pixels wide on a 300 dpi printer and may resolve the problem.
• Change the line color to black. This will let your line(s) print in the light gray fill style on the HP III printer.
• Choose the next lighter gray fill style for the line. The darker gray fill has more pixels to hit the HP III fill average, and should print out fine.
• Reposition the lines up or down slightly. Since the problem is caused by aligning the fill to the HP III's 300 dpi fill average, moving the line up or down may place it in a position to hit the average and print out. This is the more laborious of the work arounds mentioned in this article because it will take several tries before you find the right position for the line to print out.

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.