Idle Time

Being a reader of Dave’s Mechanical Pencils has gotten me interested in block erasers as companions to the pencils themselves. My first mechanical pencil was a Pentel Twist-Erase III (QE515), which I chose for its wide and long built-in eraser, but, thanks to Dave, I have since switched over to a Uni Kuru Toga * for writing and a block eraser for erasing.

But which eraser?

Here in the United States, the most available eraser is the Pentel Hi-Polymer ZEH-10, usually in three- or four-packs. As a fan of the Twist-Erase eraser, I knew Pentel could make a good eraser (even though Dave disagreed about the Twist-Erase), so I wondered how good Pentel’s block erasers were. At the same time, once I started reading Dave’s Mechanical Pencils, I wondered how the Pentel block erasers might compare to Dave’s favorite, the Staedtler Mars.

For years, all I’d ever seen were Paper-Mate erasers, store-brand erasers, and the ZEH-10, which is the larger of Pentel’s two ZEH models. Indeed, that was the only Pentel eraser I knew about until I saw Dave’s review of the ZES-08 (the “Hi-Polymer Soft”, which sounds like it’s a different eraser compound). Then, not long ago, I spotted a three-pack of ZEH-05 (the smaller one) erasers at Stater Bros. for $2, and snapped it up.

Then all that remained was to pick up a Staedtler Mars eraser and compare them. Art Supply Warehouse to the rescue: They sell them individually for 99¢ each. Other stores sell them in four-packs for $3. (If nothing else, Pentel’s ZEH erasers are cheaper: A four-pack of ZEH-10s is currently $2.64 at Target, while ASW sells the ZEH-05 individually for 72¢.)

Prior to my buying either of those, I’d bought a three-pack of store-brand pencil leads at Target for $2. That package included a block eraser. So, since I have it, I might as well include it in the comparison.

For that comparison, I used Pentel Super Hi-Polymer (a.k.a. “Ain”) lead in the HB and 2B grades on a blank store-brand (“Corner Office”) 3″×5″ index card from Walgreens.

Let us begin.

And both comparisons with level adjustments to better show the differences:

For erasing, Pentel’s ZEH-05 wins. It’s evenly matched with Staedtler Mars on the HB test, but erases a bit better with less smearing on the 2B test. And it’s cheaper to boot!

Now let’s look at shots of the erasers after each job and see how dirty they got:

I cleaned the Target eraser (by “erasing” a blank piece of rough cardboard) between tests.

As far as dirtiness, it’s pretty much a dead heat between the Pentel and the Staedtler Mars. The ZEH-05 appears dirty over less area because I’d used it more before I began testing, so it has a slightly rounder surface. Over the two erasers’ dirtied areas, the 2B test got them about equally dirty.

The Target store-brand eraser lost badly on all tests. It didn’t do as good a job of erasing, and (perhaps relatedly) the dirtied eraser compound didn’t come off the eraser body. It stuck to it. Reminds me a bit of the Pentel Tri-Eraser, which has the same problem.

In case you’re wondering, I brought the Tri-Eraser into competition after taking the above scans and photos, and found that it is almost but not quite as good as the Staedtler Mars. It doesn’t erase quite as well as the Pentel and Staedtler block erasers, because of that dirty-eraser-compound-sticks-to-the-eraser-core problem. The one advantage it has over the Staedtler Mars is the same as Dave found: Not as much smearing as the Staedtler Mars did.

So, there you have it: The Staedtler Mars does a good job, but the Pentel ZEH erasers (assuming the ZEH-10 and -05 are made of the same stuff) are both slightly better and a bit cheaper.

• * The best deal I’ve seen on the Kuru Toga is on OfficeMax’s website for $7, and for the same price at Art Supply Warehouse, both online and in their store. If you want to look for it in stores, the OfficeMax page has a photo of Sanford’s embarrassingly-plain US packaging for it. (For comparison, here’s how Uni-ball UK packages it.) ↶

I wanted a Moleskine Volant, but I didn’t want to pay $3 each for them.

So I made my own notebook instead. It’s A7, which is just a little wider than the Volants I’d been looking at.

I’d initially lettered the cover (to distinguish front from back) by hand, but wanted to make it a little more professional, so I bought a Fiskars Ultra ShapeXpress shape-cutter. Here’s a video showing it in action. I printed out a template of the cover text, cut it out, and filled it in with my pen.

The notebook is ruled, and I keep a Zebra TS-3 mechanical pencil clipped into it.

Here’s the PDF of the rulings. I printed it double-sided onto regular copy paper. Obviously, I made it for US Letter, but it would be no different for A4, because each section is a little larger than A7, for reasons that will become clear in a moment.

Once printed, I cut the sections out with a paper-trimmer, then used a “medium” rounded corner punch, bought at Target in their scrapbooking section, to round off the corners (square corners will bunch up).

The cover is scrap cardboard from one of my T-shirt packs, cut to size using scissors (plus a ruler and pencil to mark where to cut) and rounded off with the same punch.

The binding is simple enough: Two staples in the spine of the book. This is why the sections I cut out are slightly larger than A7: Each page is A7, but I included a 5 mm gap between pages for the staples to go in. (This matters more for the outer sheets than for the inner ones.) If I were to leave out this gap, or shrink each notebook page by 2.5 mm to compensate, it would be possible to get four notebook sheets instead of three from an A4 sheet.

With this, I have a pocket-size notebook that’s very inexpensive (being made from materials I have anyway), recyclable, and customizable to my taste. For a future notebook, I might make it with half ruled pages and half plain pages.

One mistake a lot of people make when trying to learn the metric system is trying to memorize and use conversion factors. Do you think people in other countries measure everything in inches and then convert to centimeters?

No, they have measuring tapes and rulers in centimeters or millimeters. Such rulers are easy to come by here in the US, but the measuring tapes are not.

So, in order to solve that problem and make it easier for fellow Americans to measure lengths in metric units, I present my Centimetric Ruler. It totals 2.5 meters, and looks like this:

Despite the name, I use it as a measuring tape, coiled up and held in that shape (when not in use) by a small rubber band.

The page is US Letter (because that’s the paper I have), and you’ll need to cut out the pieces and tape them together. I recommend cutting through the tick marks so that there is no gap between them and the bottom of the “tape”.

Note that every 25th centimeter appears twice in the printout. This is to give you one centimeter in which to lay each segment over the previous/next one.

There’s nothing I can do for you for measuring mass (but scales that measure in grams are easy to come by; you can buy a digital one at Target for $20), but volume is easy, and demonstrates the elegance of the metric system pretty well:

1. A liter is equal to the volume of a cube that is 1 decimeter (= ¹⁄₁₀ meter = 10 cm) to a side. That volume is 1 dm × 1 dm × 1 dm, or 1 dm³—one cubic decimeter.
2. ¹⁄₁₀ of a decimeter is one centimeter (¹⁄₁₀₀ of a meter).
3. Imagine, or construct, a cube one decimeter to a side. Starting from one corner, make a cut in each edge, one-tenth of the way from the corner. This will produce a cube that is one centimeter to a side—one cubic centimeter.
4. Note that this cube is ¹⁄₁₀ of the larger cube in each dimension, which means its volume is (¹⁄₁₀ × ¹⁄₁₀ × ¹⁄₁₀) = ¹⁄₁₀₀₀ of the volume of the larger cube.
5. The volume of the larger cube being one liter, the volume of the smaller cube is ¹⁄₁₀₀₀ of that. ¹⁄₁₀₀₀ of a liter. One milliliter.
6. QED: One cubic centimeter (1 cc) = one milliliter (1 ml).

Knowing how volume and length relate to each other in metric, you can use the measuring tape (most easily on cuboid objects) to measure volume as well.