Where to get fine casting sand?

What it says in the title....

I have a project at work that may require very fine sand for a casting-esque process. I'm not actually pouring anything, I've got a variation on the V-process I'm using for some tooling to be used in composite manufacture.

Neither I, nor any of my colleagues, have every worked with casting before (as in actually working in a foundary) so we're a bit stumped on where to get it! Google ain't much help.

Cheers.

I think its more commonly called foundry sand and google should throw up a local supplier? If its for a small amount a local foundry will probably sell you a bucket load?

I've had this link for years and have no memory of why:

John Winter foundry and dental supplier - Moulding Sands

I believe it has to have a high clay content. Foundry industry used to gravitate to areas that had the right sand I believe.

Calling Big Pete, come in Big Pete!

Pretty sure Big Pete put a link up about casting sand a while ago.
He'll know.

I have a book (kindly donated by Cheb) that will have the info but fuckwit that I am I don't know where the book is right now.

I think the major problem is that I don't know the proper name for this stuff

Originally Posted by Mr. Dazzle

I think the major problem is that I don't know the proper name for this stuff

What is life without choices!

These people are 15 miles from MK and if they wont supply will at least tell you who they get it from.
Aluminium casting, Investment casting, polyurethane moulding, rim moulding, UK

For anyone who's interested, I'll explain what I'm actually looking to do...

I need to make some composite parts which have an err.."inside"..I can't give too much away, but essentially they've got internal cavities. The shape of the cavity is such that I could actually get a hard tool in/out. However, one of the annoying things you have to deal with in composite manufacture is thermal expansion - specifically, the mismatch between your tool and your composite part. The different rates of expansion mean that when you 'bake' a part and then cool it back down it becomes locked onto/into the tool. S'not actually possible to design it out sometimes 'cause in doing so you'd effect other properties you need.

There are plenty of ways around it with split tools, lost cores etc. etc. For various reasons I'm looking at doing something like the 'V-Process', essentially you pour sand into a bag then shape it with pattern pretty much as normal, then you draw a vacuum on the bag so the sand 'locks together' and holds it's shape ready for casting/moulding. Releasing the vacuum unlocks the sand and lets you pull/push/extract the now floppy bag from your workpeice, ready for use again.

For this you need dry, pure, clean sand. You want the sand to be locked together, so if it's wet or similar it'll loose it's vacuum when you heat it up.

Imagine what happens when you open a packet of vacuum packed coffee and you've pretty much got it!

Originally Posted by demographic

Pretty sure Big Pete put a link up about casting sand a while ago.
He'll know.

I have a book (kindly donated by Cheb) that will have the info but fuckwit that I am I don't know where the book is right now.

That memory must be filed in the same place as why I have a link to a foundry suppliers

go to a builders merchant and buy kiln dried sand, it should be pretty much perfect for what you want.

As a process alternative, Winters (link above) do sodium silicate, which you mix with the sand and it hardens in the presence of CO2, depending on how much silcate you add, the core can be either rock solid, or moderately fragile. Its called the water glass process if you want to google it, one possible advantage is a better finish on the recess.