Getting plastered in Morrope

Nearly every home and commercial building constructed in the Lambayeque Region has its interior and exterior walls finished with plaster from the factories in or near Morrope. We were recently able to see the manufacturing process from start to finish. Not surprisingly there is almost no technology or sophisticated equipment involved, nor is it needed.

It all begins with underground deposits of gypsum rock. To my knowledge there is only one mine in the region, located 11 miles north of Morrope. We were not able to go to the mine but it was described in detail to us. The gypsum deposits are shallow. Men using shovels remove the surface dirt, and using iron spud bars break the exposed rock into manageable chunks which are hand-loaded onto trucks. Each truck has a capacity of 20 tons. At the factory the trucks are unloaded by hand. It takes two men one hour to unload a truck.

What happens next is determined by the intended use of the gypsum…there are two products that can result from the mineral: plaster or a soil conditioner used for agricultural purposes. The factories at Morrope produce both.

Making soil conditioner is the easiest and fastest of the two. Strong arms and sledge hammers simply make small rocks out of large ones. It takes a six man crew three hours to reduce one truckload. The small rocks are placed in buckets and then dumped into a surprisingly tiny crusher that grinds them into fine powder. Bags placed under the crusher’s downspout are filled and then sealed individually with a small hand tool.

Rocks destined for plaster go through an additional step. The rocks are placed into piles of predetermined size and then completely covered with large amounts of wood. The wood is then set on fire and rice husks are placed on top to force the wood to ‘char’ instead of burning with an open flame. We were told that the wood “comes from the desert” and that rice husks are a worthless by-product of rice processing and are free for the taking. There were enormous amounts of each piled around the property.

After two days only the blackened rocks remain. They’ve lost 75% of their water and through a chemical change are now no longer gypsum but instead are ‘plaster of Paris.’ The finishing steps are the same as for the soil conditioner…big rocks to little rocks to powder to bag.

The factories operate Monday through Saturday 6:00am to 1:00pm and produce an impressive 30 tons of product per day. Plaster is sold in 15lb bags for $0.29 and 26lb bags for $0.46. The soil conditioner is packaged in 110lb bags and costs $2.15. The factories will sell individual bags to the public but most of their output is destined for building contractors and retailers.

One of several crews at the factory. It’s not hard to figure out who the boss is. As usual, people were willing and eager to talk about their jobs and answer any questions. It was an enjoyable and informative experience.

Tom