Why do dry-wipe pens stop permanent markers from working on a whiteboard? Bonus question: How can you counteract this effect?
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The ink in dry erase pens are suspended in a solvent, and when the solvent dries it leaves behind the dry ink. This ink can just be wiped away because it’s not absorbed into the dry erase board.
Permanent markers work the same way, except the ink doesn’t wipe away. It still doesn’t get absorbed into the dry erase board but it doesn’t wipe away because of its formulation.
Long story short, the solvent in the dry erase marker ink also works on permanent marker ink, and then the permanent marker ink binds to the dry erase ink instead of the board.
To answer your second question, there are industrial sharpies that use different solvents that might prevent erasing on a white board.
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Oh this is really interesting!
Dry-erase markers and permanent markers are “almost” the same thing. They both use pigments inside of a sticky resin as their “ink”. They both use alcohol to keep the ink a liquid inside the tube.
But dry-erase markers have one more thing inside that liquid that lets them be wiped off of smooth surfaces, silicone.
When you write on a dry-erase board both the resin AND the silicone come out onto the board.
And here’s what’s neat, they dry at slightly different speeds! The silicone dries first, and then the pigmented resin dries ON TOP of the silicone. The ink isn’t touching the board! Then when you go to wipe off the “ink” it is sliding off the layer of silicone that is underneath it.
You can see this sometimes if there is a side light on the board. You will see a “ghost” image of what you had written still on the board. This silicone needs to be disolved in order to remove it, so you need some “board cleaner”. This is usually just the same isopropyl alcohol that is used to inside of the marker.
So why do dry-erase markers prevent permanent markers from writing on same surface? Well, it’s the same thing that lets you wipe off the dry-erase marker, an invisible, slippery layer of silicone.
Dry-erase markers are a fascinating technology!
You can remove permanent marker from a dry erase board by scribbling over it with a dry erase marker.
Both are inks in an alcohol solvent solution + a polymer. Permanent markers are an acrylic polymer, which helps it stick to surfaces (dry erase use an oily polymer that wipes off.)
So you have a liquid ink that dries in place. But once the ink has ‘dried’ any fresh application of the alcohol solvent (such as in a dry erase marker) will make the ink dissolve again.
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