Sand casting is still used in industry - somebody mentioned engine
blocks, that's one place. And I've known people who did it all the
time for various things. Sure......... But
Well these days engine blocks are done in lost foam, no cores are
necessary.
My point of view is what do you want to achieve and how fast do you
want to achieve it?
With investment casting, you have to wait for the plaster to set,
and you have to wait 12-24 hours for the plaster to finish the burn
out cycle. If you’ve screwed up you find out after you devest the
casting. If you’re successful, then you will be presented with a nice
black piece. If you aren’t successful then you have to start again.
Also if you were short sighted, and only used an original wax model,
then you have to make a new wax model. The smart person makes a cold
cure rubber mould 
Dead smooth surfaces can be achieved.
With traditional sand casting, you start with a hard model, pack the
sand around it, remove the model (the more complex the model the
more mould pieces… imagine casting a cup and saucer with a spoon in
it), pour in your metal. The packing takes a little time, but far
less than investment casting. If you bugger up the mould, you can
start again rapidly. Usually a grainy surface, but this is dependent
on the size of the grains of sand. You can get close to investment in
surface fineness, but you’ll never match it.
Then, of course, there’s lost foam casting, this takes even less
time to do than traditional sand casting, and has an added advantage.
No seams.
Now to the disadvantages.
Investment casting… takes a looooooong time, the model is
destroyed in the casting process. The plaster powder can kill you, so
breathing protection is mandatory.
Traditional sand casting… doesn’t take a long time for the
casting, but depending on the complexity of the mould, there may be a
lot of time spent cleaning up mould lines.
Lost foam casting… the amount of time it takes to do lost foam is
ludicrously short. The real disadvantage is that the model is
destroyed, and polystyrene models cannot be easily moulded, you need
special machines set up for it. The models are one-offs (I’m
investigating a way to used polystyrene beads and a burnable binder,
but haven’t been successful).
Casting sand can be plain sand no additives, sand and water, sand
and oil, cement and oil, sand and chemical binders, Delft clay. There
are a few others that I’m working on that include baby oil and other
industrial/art casting powders.
Pretty much anything shape that can be cast in plaster, can be cast
in sand, and vice versa.
Of course the above is when you do it yourself, when you pay someone
else to do it, who cares how it’s done, as long as you’re the happy
customer
Regards Charles A.
