Via microwaves: Isolation of Thenard’s Blue

1. Content

A Little Bit about the history of the pigment
Making of thenard's blue

Result

2. Thenard's Blue/ Cobalt Blue
Cobalt blue in impure form had long been used in Chinese porcelain,
but was independently discovered as a pure alumina-based pigment
by Louis Jacques Thénard, in 1802
Germany was also famous for production- especially the
Blaufarbenwerke ("blue-color works," in German) of Schneeburg.
The dye is not to be confused with Prussian blue, which is an
intensely-blue pigment based on iron and cyanide, that contains no
cobalt.

3. Isolation of Thenard's Blue
Thenard's Blue is a deep blue pigment, which is
used as a colour for ceramics, due to it's chemical
resistance.
Cobalt blue is toxic when inhaled or ingested.
Potters who fail to take adequate precautions
when using cobalt blue may succumb to cobalt
poisoning

4. Procedure

Weight and mix 0.85 g
of Cobalt-
carbonate(CoCO
3
), 1g
of Aluminium-
oxide(Al
2
O
3
) and 2,75 g
of Potasium-chloride
(Kcl) in a mortar

Put this mixture in a
fire-proof container and
cover it

Put it in the microwave
(850W) for 5 minutes

5. After cooling, and
crashing in the mortar,
boil it in a baecker
with 10 ml of
Hydrochloric acid
Then wash it with 25
cl of water → solid is
filtrated and dried
Procedure

6. Observations and evalution
The Educt-mixture is dark gray → a deep blue
powder → colour becomes more intensive after
boiling with Hydrocloric acid
CoCO
3
+ Al
2
O
3
→ CoAl
2
O
4
+ CO
2

7. Thank you for the attention it was fun to work on this project for us
we hope we haven't bored you :)