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What kind of pen should you use with your planner?

The best answer is “one that you enjoy writing with”. You want the experience and the results to be as nice as possible.

Most people whom I have heard ask that question are actually asking a slightly different question: “Should I use an erasble pen?” They don’t like pencils because you always need to sharpen them, the graphite smears, and it makes you feel like you’re back in elementary school.

Ink, on the other hand, is permanent (by comparison). If you make a mistake, you’re stuck with it. And what if your plans change? Isn’t there a way to get the flexibility of pencil with the professional look of pen?

I’ve been using an erasable pen for several years, a Pilot Frixion with Navy Blue ink. It feels smooth, looks great, and erases cleanly.

“But what about leaving it in the hot sun? My friend’s husband’s brother’s college roommate left his on the dashboard of the car and all the ink disappeared!”

Now personally, I’ve never had this problem. It’s not something I’m worried about happening. It’s not something you should worry about happening either. First, it’s not likely happen (more on that later). Second, if it does happen, you can get it back again.

Pilot Frixion pens use a kind of ink called thermochromic ink. That’s an ink where the temperature determines the color of the ink. It starts out colored at room temperature. When you “erase” the ink, you’re not rubbing it away like a pencil; you’re using friction to raise the temperature of the ink.

This is an incredible behavior, but it’s where some people get stuck. There are other ways you can raise the temperature of the ink. (The Rocketbook Wave is actually designed to be erased in the microwave.)

So, yes, if you leave your planner sitting on the dashboard all afternoon, in Phoenix, in August, you might accidentally erase it.

But you can get it back.

When you heat thermochromic ink, it changes from colored to clear. The ink inside a Pilot Frixion pen is designed to make this transition around 65 °C (149 °F).

Do you know what happens when you cool it down below —20 °C (–4 °F)? That’s right—it transitions from clear back to colored.

Here’s a notecard that I erased by putting it in an oven at 150 °F for 20 minutes. (Kids, don’t try this at home.)

An index card with no visible writing.
Erasable ink after spending 20 minutes in the oven. If you squint, you can still make it out, so don’t rely on this for destroying sensitive information.

Here’s the same card after spending 45 minutes in the freezer.

An index card with legible writing.
Erasable ink after spending 30 minutes in the freezer. Note that some previously-erased text on the third line is now visible.

For comparison, here’s the original, before it baked in the oven. Note that it’s darker than what came out of the freezer, though I may have just not left it in the freezer long enough.

An index card with legible writing.
Erasable ink before I started playing thermal games with it.

This will cause all the thermochromic ink on the page(s) to transition back to the colored state, whether the ink was accidentally transitioned in the car or intentionally erased.

Obviously, you shouldn’t use an eraseable pen for documents where permanency matters, like on a check, a legal document, or even when addressing outgoing mail. (If the address accidentally fades on that birthday card you sent, the post office might not know about the freezer trick.)

Paired with your planner or a notebook, erasable ink gives you the professional look of ink with the flexibility to change your plans or fix mistakes at any time. And if your planner should happen to spend the afternoon on the dashboard of your car, you can pop it in the freezer to get everything back.

Question: What kind of pen do you use? Share your thoughts in the comments, on Twitter, LinkedIn, or Facebook.