I've spoken a lot about my favorite paint markers over the years (yes, I'm looking at you water based Sharpies, Molotow and Montana markers!) I've suggested many times that when you first buy a paint marker that you should "burp" it to get the air flowing. Well, one thing that I could never figure out (and this has been happening for MANY years) is how to stop the paint markers from "throwing up" (or leaking) all over the place when one goes from low altitude to high altitude.
Last week, one of my wonderful Colorado students suggested that before you use a marker that has gone from low to high altitude that you take a paper towel or rag, hold the pen tip up and press down on the nib once. This will get the air flowing throughout the marker. Yes, the pen will leak a little bit when you first do this but it stops immediately. Afterwards, as needed, shake and pump the tip on scrap paper before you use it on your page.
I hope that this helps you as much as it helped me! Just say no to leaky markers!
More on My Favorite Pens Here (lots of links!)
Derwent Graphik Line Painters