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Got it. Whenever we come across a dead marker, we throw the board away and get a blackboard instead! About that, could we have a similar article on blackboards

Got it. Whenever we come across a dead marker, we throw the board away and get a blackboard instead! About that, could we have a similar article on blackboards and chalk? All I know is that there was much ado [0,1,2] about a certain Japanese manufacturer shutting down a couple of years ago. They, allegedly, made the best chalk and prices on the secondary market rose high after the news came out. [0] https://www.reddit.com/r/math/comments/3a05u3/why_mathematicians_are_hoarding_this_special_type/ https://www.reddit.com/r/math/comments/3a05u3/why_mathematic... [1] https://www.reddit.com/r/math/comments/3axqxe/hagoromo_president_explains_why_he_closed_down/ https://www.reddit.com/r/math/comments/3axqxe/hagoromo_presi... [2] https://www.reddit.com/r/math/comments/3rciv0/an_update_on_where_to_buy_highquality_chalk/ https://www.reddit.com/r/math/comments/3rciv0/an_update_on_w...

NegativeLatency 9y ago
Also the new chalk that makes dust that is safer to breathe doesn't write as well as the older kind that is bad for your lungs. Very similar to leaded/unleaded solder.
- jacobolus 9y ago
  Leaded solder is actually generally better for your health (just don’t eat it). The unleaded stuff has really nasty flux, and requires much higher temperatures, meaning the fumes are quite a bit worse. Make sure you have very good ventilation when working with unleaded solder.
  - analog31 9y ago
    Completely as an aside to the thread, if you're doing this a lot, try Kester K100 alloy, which is much lower melting than the first generation Pb-free, and behaves a lot more nicely. Not like genuine PbSn, but closer. Techni-Tool has spools of it in different diameters.
algeom 9y ago
I bought a 20 year supply of that chalk when the demise of Hagoromo was announced, but it turns out that production of that particular product was turned over to a Korean company. I’m still using my legacy supply, so I can’t comment first-hand on old/new comparisons, but I haven’t heard any complaints.
- Kluny 9y ago
  How much is a 20 year supply?
amluto 9y ago
I used to have the pleasure of working in an office with genuine slate blackboards. They were very pleasant to write on (the chalk seemed to need less pressure to make a nice line and they always cleaned up perfectly), but using them was rather dusty.
- Bromskloss 9y ago
  Is that a board made of a single piece of slate? How large can those be made?
  - bikenaga 9y ago
    The largest boards in our building look like they're around 5' x 8-10'.
adrianN 9y ago
I found this video very interesting: https://www.youtube.com/watch?v=UCroFiwllH8 https://www.youtube.com/watch?v=UCroFiwllH8

NegativeLatency 9y ago

Also the new chalk that makes dust that is safer to breathe doesn't write as well as the older kind that is bad for your lungs. Very similar to leaded/unleaded solder.

jacobolus 9y ago
Leaded solder is actually generally better for your health (just don’t eat it). The unleaded stuff has really nasty flux, and requires much higher temperatures, meaning the fumes are quite a bit worse. Make sure you have very good ventilation when working with unleaded solder.
- analog31 9y ago
  Completely as an aside to the thread, if you're doing this a lot, try Kester K100 alloy, which is much lower melting than the first generation Pb-free, and behaves a lot more nicely. Not like genuine PbSn, but closer. Techni-Tool has spools of it in different diameters.

algeom 9y ago

I bought a 20 year supply of that chalk when the demise of Hagoromo was announced, but it turns out that production of that particular product was turned over to a Korean company. I’m still using my legacy supply, so I can’t comment first-hand on old/new comparisons, but I haven’t heard any complaints.

Kluny 9y ago
How much is a 20 year supply?

amluto 9y ago

I used to have the pleasure of working in an office with genuine slate blackboards. They were very pleasant to write on (the chalk seemed to need less pressure to make a nice line and they always cleaned up perfectly), but using them was rather dusty.

Bromskloss 9y ago
Is that a board made of a single piece of slate? How large can those be made?
- bikenaga 9y ago
  The largest boards in our building look like they're around 5' x 8-10'.

adrianN 9y ago

I found this video very interesting: https://www.youtube.com/watch?v=UCroFiwllH8 https://www.youtube.com/watch?v=UCroFiwllH8