An email today about graphite properties. Anybody any ideas?!

I understand in its natural form the finest artists graphite had the unusual property of making a lighter mark when pulled in one direction and a darker mark when pulled in contrasting direction. Is this true in your experience?

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Simon, do you mean when it is in its natural form or when it has been mixed with clay to form drawing pencils? I am an artist and have tried this and cannot say I can see any differerence with artist quality pencils.

In its natural state graphite consists of an hexagonal arrangement of carbon atoms (hexagonal in 2 dimensions) stratified in layers one atom thick. This is what gives graphite its lubricating qualities. I suppose the stratifications could mean that directionality has some bearing. Just a guess mind.

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I've got a lump of graphite from Seathwaite on my desk which I have tried doodling with in the past - I can't say I noticed any difference in the darkness of the lines. I must conduct a more scientific test later....

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Right, I've conducted the highly scientific test of drawing a line moving right then drawing another one moving left, and repeating several times. The bit of graphite I've got isn't brilliant, it's not the best quality but it does leave its mark. I couldn't see any real difference in darkness of the lines, apologies for not posting a pic but I don't have a digital camera at work...

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To All:

I posed the graphite drawing properties question to Simon and he kindly posted it on your site. I am an artist and interested in traditional drawing and painting materials.

At one time I read a reference (source now lost) that claimed the unusual property of the finest natural graphite to make lighter and darker marks depending on the direction of the stroke on paper. This could just be wrong of course, but JR points out that the atomic structure of natural graphite suggests the claim perhaps has validity.

My understanding of the early pencil making process involved sawing graphite ore to size and fitting the resulting rectangular rod to a trough in soft wood then mating it to a matching trough, gluing and so forth. If there is an ideal cleavage direction naturally the workman would have to carefully note it and cut the rod accordingly.

Historic references to artist quality graphite praise as the finest that which came from England. Might the consistency of tonal directionality be one of the valued properties?

I appreciate your thoughts on this subject

Ed

Hi Ed, one of the problems we have with Seathwaite graphite is that all the high-quality graphite was worked out long ago, so it's hard to say whether it had any sort of cleavage that could be exploited when making pencils. The bits that you can find today, like the one on my desk, tend to be quite amorphous and intermixed with the host rock which does interfere with the marking properties. Ian Tyler wrote a good book about the Seathwaite mines which discussed the uses of graphite, but I don't recall any specifics about exactly how pencils were made from it other than the method you describe.



Certainly, the Seathwaite graphite was reckoned to be the world's best, being far purer than that found on the continent at the time and I don't know of any sources found in modern times that are comparable.

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