I have always used the Staedtler Mars Plastic as my everyday eraser, and I don’t think there is any question that it is a very good eraser. However, since in my view Pentel dominate the world of mechanical pencils and mechanical pencil leads, it seems logical to give their erasers a try.
Staedtlers history is with woodcase pencils, and I get the impression woodcase pencils are still very important to them, maybe more important than mechanical pencils, and thus I have always assumed that if there was any choice required they would optimise their erasers for woodcase ceramic leads rather than polymer leads. On the other hand I don’t think there’s any argument that Pentels mechanical pencils are more important to them than their woodcase pencils. Not to imply their woodcase pencils aren’t important, but their mechanical pencils are a worldwide force whereas their woodcase pencils are basically Japan-only. Thus I am tempted to think that Pentels erasers would be optimised for mechanical pencil polymer leads, should there be any conflict between eraser requirements.
The Pentel Hi-Polymer ZES-08 measures 43mm long x 24 x 12, which is smallish by my standards and in comparison to the Mars Plastic. Surprisingly it is made in Taiwan. I don’t recall any Pentel mechanical pencils being made in Taiwan.Like many erasers the Pentel Hi-Polymer has a sliding cardboard sleeve. The eraser compound is white, and soft, noticeably a different white to Mars Plastic and definitely softer. Perhaps this softness might be an important consideration on thinner or more fragile papers, but in general use I found the softness a little annoying as it made the whole eraser flex and bend more when under pressure, and thus it felt a little less under control. As claimed, the eraser waste sticks together. I tried to compare the amount of waste produced and how well it stuck together with Mars Plastic but gave up. Too hard to be objective, but I am tempted to think the Pentel eraser wore down a little quicker than Mars Plastic.
Time for some comparison tests. Below are 4 tests series, Hi-Polymer in comparison to Mars Plastic.
Mechanical Pencil polymer lead, HB hardness.
Mechanical Pencil polymer lead, 2B hardness. Woodcase Pencil HB and Mechanical Pencil HB.Woodcase Pencil 4B hardness. What did all that testing tell me? It told me that it’s pretty hard to tell these two erasers apart when it comes to erasing performance. Both do a great job on both woodcase and mechanical pencil leads. As expected, although still good, their worst performance was on the woodcase 4B lead. Smearing is always a little bit of a problem with such dark soft leads. This 4B test was the only one where I thought there was a little bit of a difference between the two erasers - it’s very close, but I did feel that Mars plastic did a slightly better job than Pentel Hi-Polymer on the 4B test. But very close, as I say.
Overall then, the Pentel Hi-Polymer is an excellent general purpose eraser, a worthy competitor to Staedtler Mars Plastic.