Is pencil lead magnetic? 1

[Jori1]

Hello,
I searched pencil lead and magnetic because my second graders just brought me magnets with pieces of pencil lead attached showing that at least this pencil lead is magnetic. They, and I, wanted to know how. Your site/posts came up. OK, I'm not really an engineer like ya'll are, but try teaching a room full of wriggly, excited 7 year-olds and see how much "engineering" it takes! Anyway, from your posts it seems there could be several reasons, from iron in the graphite to iron particles coming off the forming machines. I just wondered if you had found a definitive answer. The children and I eagerly await your answer.
Thanks
Jori
PS I did want to be a human factors engineer 40 years ago but alas it wasn't encouraged for girls back then.

 

[MintJulep]

Pencil "lead" is graphite and clay.

Clay can contain iron.

So I'd guess that depending on the clay used pencil lead may or may not be magnetic.

Could be some opportunities for classroom experiments here.

See if you can find examples of magnetic and non-magnetic pencil lead.

Get some graphite powder and see if it is magnetic.

See if you can find some magnetic and non-magnetic clay.

Mix graphite and clay and make your own pencil lead.

Does mixing non-magnetic graphite with non-magnetic clay cause the mixture to become magnetic?

Etc.

 

[MagBen]

yes, pencil lead is not really lead, but rather it consists of clay (SiO2) and carbon (graphite). all three of them are diamagnetic.
Two sources you can get a bit of ferromagnetism (generally, not scientifically, refers to magnetic): 1. Fe impurity, 2. grain boundary disorder from super small graphite particle.

 

[dik]

I thought clay was formed from calcium, sodium and potassium aluminosilicates... much softer material (feldspar) than silicon dioxide (quartz) and much thinner parts (platlet particles only a few angstroms thick). About 30 years ago, my youngest son who was only five or six when I gave him a magnet and he ran around the house checking for things that were magnetic... that went well until he checked the screen of our colour TV... it took about a week for it to de-gauss... he produced a beautiful coloured pattern that eventually went away.

Dik

 

[IRstuff]

Doesn't take much field to mess up a CRT. We had some display software for a system, but we installed it upside down on another platform, and the software guy got lazy, so we flipped the monitor. The colors went bonkers, but we got used to it. After about 3 months, the software guy found enough time to reprogram the display routine, so we flipped the monitor back, but the colors never recovered, even after 6 months.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529

 

[Compositepro]

Standard pencil leads are as described above. But, it would be extremely easy to make a pencil lead using magnetite (black iron oxide) as the pigment rather than graphite.

Plus this:

http://www.eng-tips.com/viewthread.cfm?qid=307702

 

[btrueblood]

Cpro, not sure if the resulting "lead" would leave a decent mark on paper?

 

[IRstuff]

It's not pencil lead unless you have the possibility of do this:

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529

 

[EdStainless]

Many art pencils are primarily graphite but blended with various oxides. and the grain size, clay ratio, and compaction force all combine to give the color and line density. Many of these additives could be magnetic.

There are may 'inkless pens' or 'everlasting pencils' on the market that use metal tips, these are mostly lead alloys. The mark that they leave is mostly metal oxide.

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P.E. Metallurgy, Plymouth Tube