Cleaning rusty dividers

One of the things that keeps me interested in bookbinding is how it encompasses so many different fields. Before working in bookbinding for too long, I quickly realized I needed to learn a little about woodworking, metalworking, tool and die making, fabrics and textiles, graphic arts and typography, materials science, and so on. These days (at least, for the past century or so), if you want to do a good job at bookbinding, you need to be able to service your own tools. One frequent question/complaint I hear from my students is about dividers. What are they? Is this a dividers? How about this? Well… those may be listed as dividers, but they’re not exactly what you’re looking for. Using a dividers is, to me, one of the more important steps in one’s development as a hand bookbinder. A good set of dividers can make your work more accurate and efficient. It’s important to get the best tool you can afford, and certainly a decent pair of dividers is affordable; you just may have to do some hunting. I have a considerable amount of brand loyalty in this area, and Starrett is the only kind of dividers I like. Though they can be expensive to purchase brand new, it is relatively easy to find Starrett dividers at flea markets and on ebay. The down side is they will often have a considerable amount of rust.

Removing the rust is a quick and easy way to make your new find your own. All you need is a little citric acid, some metal polishing compound, and a light machine oil such as 3 in 1.

I have seen bookbinders perform experiments in removing rust with Coca-cola (which contains citric acid), but I don’t usually have that around. I do keep some citric acid (available in natural foods stores in the preserving/canning section) on hand for making jam, to balance the acidity of low-acid fruits in order to properly set the pectin. After doing a little web scouting on the topic I turned up this Wikipedia article on pickling metal which I found fascinating, and made me feel a little more confident in removing rust this way. One thing to note is that even though citric acid is safe to ingest, it is still an acid, and how strongly you mix it determines its safety to use. I used about 1 teaspoon for a 9×9″ square pan filled to about 2-3cm deep with tap water.

Visible rust starting to create pits in the metal; citric acid available at natural foods store

Before: visible rust starting to create pits in the metal; citric acid available at natural foods store

After only an hour, much of the rust has lifted off

After only an hour, much of the rust has lifted off

After soaking another hour in the citric acid, then wiping down with a metal polish, rubbing with a light machine oil, then drying off.

After soaking another hour in the citric acid, then polishing any pitted areas with a metal polishing compound such as jeweler’s rouge, rubbing with a light machine oil, and finally wiping dry.

It is a really satisfying feeling to clean up an old tool like this. Using a light acid bath instead of scratching away at the metal with a steel wool or brillo pad is much better, in my opinion: the acid removes the rust only, not the unaffected neighboring metal surfaces. The acid bath also removes rust easily from threaded parts of the tool and other hard to reach areas. Just be sure to dry the tool completely afterward and don’t hold back with the oil. Let the tool stand with the oil on it for at least a few hours at warm room temperature to let it seep in, then wipe it completely clean with a soft cloth. The dividers pictured above now works smoothly and is ready for adventure.


Filed under Tool Talk

3 responses to “Cleaning rusty dividers

  1. Great post, useful information. It is also important to remember that Starrett made three styles of dividers, and all three are available in the two older catalogs I have, Numbers 26 and 27. The dividers you have pictured are the “Yankee” pattern, they also made a “Toolmakers” Dividers that has round legs and the adjustment screw is threaded through them, and the “Fay Pattern” that has machined square legs above the screw, which is also threaded through. Jeff

  2. Maryanne

    Very informative article. Thank you!

  3. Thanks for posting this Juliayn, some useful information in it. I’ve got a few old tools I need to ‘clean up’, I’ve never heard of using Coke before but I’ll give it a shot!

    Keep up the good work! ~ Paul

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