One question you see a lot and it takes many forms. Can I use markers in this book? I’m looking at these pens, do they bleed?
Firstly let me clarify there’s bleed and then there’s just show through, bleed is when the colour pigment spreads from where you place it. So if you ask does it bleed the answer might be no but it can still show through.
Alcohol Based Markers
These can bleed on a lot of papers though for most it’s not a problem as it is minimal but they will most certainly show through. The alcohol in the ink soaks into and saturates the paper which causes the colour to show up on the other side, though this is also the benefit of alcohol markers because the wetter the ink the better they blend.
Water Based Pens
These don’t stay as wet so don’t really bleed, but dependent on the paper can still show through. Different tips can make a difference here though, a brush tip doesn’t require as much pressure as a bullet/fibre tip or fine liner so tends to fair better on thinner papers.
Now these are a law onto themselves, they sit on top of the paper, they don’t soak in at all but the ink is heavy so can show through on lighter weight papers. The ink will stay wet for a while and because it is on top of the paper they smudge easily, be careful to let them dry before working over them or closing a book.
If you are thinking, I’ll just use pencils you might have to think twice as poor quality paper can mean even pencil will show through. In the case of water colour pencils it is better to consider them more like water based pens rather than pencils as adding the water will change how the paper reacts.
As a general guide single sided print is good for most media but if you use alcohol markers and it bleeds badly your pens will dry up quickly. (the paper is too absorbent though paper like this is few and far between in my experience of various books.) If you are colouring in a single sided book though always place a plain sheet of card under the page in case any colour comes through.
If the book is double sided print, never use alcohol based markers, unless you really don’t care for the image on the reverse.
There are ways of roughly gauging which pens will be all right for double sided books. If you open the book and hold up one page and don’t see the print coming through you should be fairly safe with any water based pen, gel pens or pencils.
If the print is visible like this then water based brush tips and pencils are reasonably safe, maybe light applications of gel pen.
However if you see the print on the other side with the page flat in the book it’s pencils only (or return it because it’s pretty low quality paper if you can see the print like this.)
Finally if the paper has a heavy texture (a lot of tooth) it’s designed more for pencils, smoother paper will take pens better.