When do you have to worry about dot gain?

[richardwalter]

Dot gain is all about the media you are printing on.
Like StudioMonkey said, uncoated papers are most affected, but all materials should be suspect until you know them.

Dot gain affects everything on the page. Images aren't immune to it. Typography is very susceptible to it. If you have tiny type or thin type or type with very fragile serifs, that type may fill in and become illegible. Even a tiny bit of dot gain on knocked out serifed text can lead to unintended consequences.

Ask the printer.
Get a proof.

In some cases, I like dot gain. I do a lot of fabric graphics. While the dot gain isn't much, it's enough that I know I can get away with a lot when it comes to image resolution.

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