Pure gypsum is white but impurities colour it grey brown or pink.
Its Marl that gives the plaster the pink colour.
Marl is a natural impurity in the rock.
And it also gives workability to the plaster.
Gypsum rock was formed when the sea water evaporated millions of years ago, which was then hidden in the earths crust, until it was bought close to the earths surface during the last ice age.
It is now about 300feet below ground.
The grey plaster is mined in the north & pink plaster in the south, but it gets delivered all over the Uk and even to Poland.
Also 95% of a bag of finish plaster is ground down gypsum rock & the other 5% is additives.
Backing plaster is 90% ground down gypsum rock & the other 10% is additives.
So every bag of plaster you use is roughly 180million year old rock.
Something to think about next time your spreading the muck.
Its Marl that gives the plaster the pink colour.
Marl is a natural impurity in the rock.
And it also gives workability to the plaster.
Gypsum rock was formed when the sea water evaporated millions of years ago, which was then hidden in the earths crust, until it was bought close to the earths surface during the last ice age.
It is now about 300feet below ground.
The grey plaster is mined in the north & pink plaster in the south, but it gets delivered all over the Uk and even to Poland.
Also 95% of a bag of finish plaster is ground down gypsum rock & the other 5% is additives.
Backing plaster is 90% ground down gypsum rock & the other 10% is additives.
So every bag of plaster you use is roughly 180million year old rock.
Something to think about next time your spreading the muck.
