Why is 'manufactured sand' a concern?
You might have seen the term 'manufactured sand' mentioned if you have been researching play sand. Most Mom Blogs that do discuss it also recommend against it and Geologist Jerry will give you an easy explanation on what it is and why they don't like it.
Think about the local sand & gravel pit you see when driving around. If you looked inside the pit you would see a bunch of conveyor belts, various silo's and buildings. Scurrying around these and the sandpit are the big tractors, loaders and excavators that dig up and haul the material to the conveyor belts.
This is how they 'manufacture' sand. Essentially it requires whatever they are digging up (it could be rock along with soil and whatever is growing on top) to be made into sand. Usually the first thing that happens is screening out the bigger rocks and stuff they want to avoid getting in the sand.
First key point: the conveyor takes it up to a Crushing & Pulverizing machine that does exactly that to the rock, sandstone, clay and topsoil they have dug up. From there it goes to various screening machines that separate it into different sizes.
Remember, most of the money the sand & gravel pits make is from supplying materials for highway building and construction projects; road base uses the most material. Many also recycle concrete from demolition sites and it all gets mixed together.
Back to the journey on what manufactured sand is. So after its separated by size then it has to be washed and here is the second key point: the crushing & pulverizing process makes dust, a lot of dust. The local regulatory agencies classify it as Nuisance Dust and it's a big concern to those that live by a sand & gravel pit.
They wash the crushed materials to get the out-of-spec materials out so it can meet building codes and be used as engineered fill, road base and concrete.
Problem is what you consider clean play sand and what is allowed to be used in concrete and road base are miles apart. Actually, thousands of miles apart.
And that brings us to our third key point concerning asthma & allergy's. Nuisance dust can really aggravate allergies and trigger asthma attacks. It is also virtually impossible to wash out and it literally takes some pretty hi-tech equipment costing super big bucks if you want it clean clean.
That's not a typo - it's my way of emphasizing what you should be looking for and expecting.
Another critical issue with manufactured sand besides the fact that the process creates a sand that is dusty, is the concern over getting it in your child's eyes. Because the machines crush the rock, the process also creates angular grain shapes which have sharp or pointy edges.
Getting those grains (as opposed to sand grains made rounded grains from waves at the beach) can be a real concern for injury resulting from scratching or abrasion of the cornea or even iris of the eye.
Hopefully now that you are armed with some knowledge of how manufactured sand is made and the issues associated with it, you will better be able to make informed decisions when selecting safe play sand for your sandbox, sand and water table and preschool sensory bin.
Remember to search for safe sands that typically come from deserts, beaches and even some rivers and streams because they do not require crushing and pulverizing.
Mother Nature is amazing - that's why this Geologist went into geology - she can make the most incredible landforms, formations and materials that mankind, and all of our technology could only dream of creating, and that's why her sands are the best.
Fortunately, I'm one of the lucky geologists that get to go out in the field and search for them.
Best regards -
License # 2250