Green sand is one of the oldest foundry molding media known to the industry; its use in the foundry goes back to the earliest times. But do you know how to get the most out of it?

While its use in commercial foundry operations has diminished somewhat, green sand still has its place in hobby foundry. Green sand can be crafted from fairly basic materials and is still used to produce solid quality aluminum, bronze, and gray iron foundries at many hobby foundries scattered throughout the world.

Green sand is also kind to the environment, as it can be recycled and reused almost indefinitely, before being discarded in favor of a freshly crushed batch.

When green sand was the preferred commercial molding material, special sand reprocessing machines were used to remove foreign objects and break down dry sand clumps and recondition the sand again for the mold shop.

Because green sand is reconditioned or re-tempered by the addition of water, it requires quite a bit of processing work to make it suitable for molding work again.

Unfortunately, the hobby foundry worker does not have the luxury of automatic processing machines, so the task of reconditioning for the hobby foundry worker is reduced to a laborious manual process, which can soon become tedious if a large quantity has to be processed. lots of sand.

When we talk about green sand reprocessing, we are not referring to the crushing or grinding of a new batch of green sand, which is a very different subject.

To recondition green sand, it is typically fed into a grit blaster to break up clumps and lumps that naturally form in the green sand mold during solidification of metal castings; much of the moisture content of the sand is also removed during this stage.

One option for the hobby worker to recondition and re-temper green sand is to use the slow hand sifting method whereby the operator manually processes the sand through a wire puzzle to break up the lumpy sand, it can then be re-cast. temper by slowly adding water and cutting, turning, and dumping the sand with a shovel.

Yes, it’s hard work and a slow process, and one that most hobby workers will quickly lose interest in.

If you want to use green sand in hobby casting, but don’t want to re-temper the sand with this hard-working manual system, then there is another way. The quickest and easiest way to re-temper small batches of green sand, such as the hobby worker would need, is to use a motorized rotary puzzle.

The Riddler is capable of processing a large amount of sand in 10 to 15 minutes, which includes the foaming and retempering process, it is virtually a three-way simultaneous process.

The quality of the green sand produced through this method is second to none, and the motorized rotating puzzle greatly reduces back-breaking labor to virtually zero. Anyone with general metal fabrication skills could easily build a puzzle, materials costs are not expensive and readily available.

The main requirements are: a small electric motor, a wire sieve, some square tubes to build the frame, plus instructions for building an efficient machine.

Solid plaster and cement renderers in the construction industry could also use this type of machine to prepare mortars and bag-applied wall finishing materials.