vector not straight

[Jiggy]

This image is part of a logo and completely made in illustrator vector. The graphic has a fully orange colour. I've scanned the result so you are now seeing a grid of red and yellow dots.

http://img695.imageshack.us/img695/7171/hoekje.jpg

The problem is that the logo is in vector so this 'corner' graphic should be sharp and completely straight. So no curves. When printed this looks slightly curved. So I scanned the businesscard and it looks like this is the result of the grid and the yellow bits of the outline not being completely visible. Which makes the edges look slightly curved... I think that's it.

The printer says this is because I haven't used a 'full' colour and because it's kind of a mixed colours, the 'grid' has to mix the dots to get to the intended orange colour. And according to them that's why it's never possible to get exactly straight lines in a colour.

Is that's true? Even in vector graphics it's never possible to get completely straight lines/fills when printing business cards?

 

[oxburger]

Yes and no. Because the orange (when printed using process inks) is made up of yellow and magenta dots, you will have areas where the screen angles overlap each other and cause it to looked jagged (This is especially true where there is a curve in the artwork). To get it to print the way you want, with straight lines, even on curved areas, you have to print the orange part of the logo as a solid spot color ink (no screens). This however will add to the cost of the printed job because you're adding a plate.

 

[Stephen Marsh]

The problem is that the logo is in vector so this 'corner' graphic should be sharp and completely straight. So no curves. When printed this looks slightly curved.

If I was going to offer an informed opinion on "completely straight", I would want to compare the original vector file vs. the scanned result previously linked.


Stephen Marsh

 

[rich apollo]

The pattern of the magenta screen is creating a wave form. The screen is constructed of rows of dots. Those rows are laid out at 105º for the magenta plate. You're restricting the dots to print in a region defined by vertical and horizontal lines. The wave form you're seeing is where the rows of dots are cutting off. I've attached a screen grab to illustrate. The arrows mark where consecutive rows of dots hit the boundary. Notice the 1-2-3, 1-2-3 pattern. Not a one-two, one-two beat, but more like a waltz.

As someone stated, printing in solids would get rid of that. Increasing the frequency of the screen would change it, and perhaps render it unnoticeable.

 

[gordo]

A simple solution might be to run the Magenta screen at 45° instead of the screen angle he's currently using.
This would align the dots with the edges of the graphic like this:

Of course FM screening eliminates the problem entirely since it has no screen angles and has a higher effective lpi. But your printer may not have implemented this capability.
best, gordo

 

[jotterpinky]

Gordo,

wouldn't the 45 degree angle still cause a problem if the vector was in a curved shape (at least in certain areas of the curve)?

 

[gordo]

Gordo,

wouldn't the 45 degree angle still cause a problem if the vector was in a curved shape (at least in certain areas of the curve)?

Yes, the problem is the relationship of angle of the screen relative to the angle of the graphic. I was just going by what the OP gave as the problematic graphic.

best, gordo