Eagle Pencil Co.'s CHEMI-SEALED method

look at the vintage eagle pencil

You can see some pencils engraved with CHEMI-SEALED.

CHEMI-SEALED is simply put

The method developed by Eagle Pencil Company,

Attach the pencil lead and the handle firmly

This is a construction method that prevents the pencil from breaking when dropped.

About this technique

It is written in detail in Henry Petrowski's [Pencil].

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In 1933, Eagle Pencil's research and development department prevented splitting of the wood stem by improving the bonding method and enhancing the strength of the wood stem.

First, the pencil lead is dipped in sulfuric acid to remove the wax film on the surface, and then dipped in calcium chloride to coat the surface with a gypsum film.

Next, soak the wooden stem in a coagulant so that the wood fibers are surrounded by a hard coagulant film so that the handle does not crack when you press the pencil.

And finally, when the core and the handle are glued together, the core and the handle are firmly adhered unlike the previous process.

This method of bonding the lead and the handle at the same time was called the CHEMI-SEALED method by Eagle Pencils.

Thanks to this construction method, Eagle Pencil Company could claim that the strength of the existing Mikado pencil lead was improved by 40 percent and sales increased by 34 percent.