# Casting Sand Recipe



## ShedBoy (Jul 18, 2011)

I need to make some casting sand, I can get bags of bentonite powder no problems but what sort of sand do I need. Can I used beach sand, its the finest I can find? All you old hands give up some recipes, core sand recipes will also be required. Thanks in advance
Brock


----------



## tel (Jul 18, 2011)

I use yellow brickies sand, that has a certain amount of clay in it already, so you can cut back the bentonite a bit. How much? Trial ans error really, start with about 5% bentonite and add more if needed.


----------



## ShedBoy (Jul 18, 2011)

What about core sand Tel, I read you put molassas in your mix. Any ratio hints 
Brock


----------



## Herbiev (Jul 18, 2011)

Hi Brock. Instead of molases use "water glass" used for preserving eggs. Its chemical name is Sodium Silicate. You mix this with the sand then pass over some CO2 (carbon dioxide). These cores are extremely strong and heat proof. 
I have attatched a small PDF from Foseco foundry supplies explaining the mixing process. 
http://www8.svsu.edu/~rtuttle/FRG/HOWTOs/Sodium Silicate Coremaking.pdf
Hope this helps 8)


----------



## bezalel2000 (Jul 18, 2011)

Hi ShedBoy

Moulding sand (green sand, since you've already said you have bentonite) is always a compromise ;

It has to be open enough to let the steam out but fine enough to give a smooth surface.

It is best to avoid river sand that contains small rounded grains for two reasons.
1. small river pebbles can retain moisture and could shatter due to thermal shock of liquid metal flowing over it.
2. the bond will tend to be poor due to grains slipping one past another - sharp silica sand is much better.

In the extremely unlikely event you can't get sharp silica sand there are some alternatives that work very well.

1. extremely fine blue stone (railway ballast) crusher dust
2. fresh granular volcanic ash.   

About a decade ago, I set up a small foundry on Tanna Island Vanuatu, for the locals to manufacture there own cooking hardware 
In some of the pacific Islands of Vanuatu, believe it or not, there is no sand to be found any where, the beaches are actually made of broken up coral and not very suitable for casting.   The spatula below is one I bought back with me, It was cast in ash from Mt Yasu volcano. along with every thing else made in that foundry. 









The point is this - I doesn't really matter too much what type of sand you use, providing,

It Bonds well, (With appropriate bonding agent e.g. bentonite)
it Breaths well (adequate permeability to prevent steam holes in your castings) and
it Behaves well ( i.e. doesn't retain water in the particles or break down with thermal shock) 

Best thing to do is try it out.
Study carefully foundry safety and commit to following it. (I follow a list of foundry safety rules let me know if you want a copy.) 
Make a mold and vent it well - if it holds up OK, pulling the patterns out then get well protected with PPE and pour it.

What comes out of the mould will often tell you exactly what you did wrong. 

Good luck and keep learning

Bez


----------



## ShedBoy (Jul 18, 2011)

Bez a copy of them safety rules would be great. I am new to this so any help will be good. Love the spatula, I have an old potato masher at home which works great which I would not mind recreating because I can not find a new masher which equals it. 

Herb, thanks for the pdf, any info is a help for me.

Brock


----------



## tel (Jul 18, 2011)

For the molasses sand dilute molasses 10:1 with water and use that as the damping agent, replace the bentonite with plain flour. Bake the cores in the oven until hard and dry.

The Sodium Silicate brew works as well, but, for me at least, the Sodium Silicate is harder to get - we buy molasses in 200l drums for the cattle.


----------



## bezalel2000 (Jul 18, 2011)

Hi Brock

I hadn't used baked cores until recently. 

 So I was heading down the "make your own sodium silicate" track by dissolving crystal kitty litter in a solution of drain cleaner.  i.e. sodium hydroxide and powdered silica gel (about a 6:4 by weight IIRC)
Then put the green cores in a closed box with a cup vinegar and bicarb soda for the CO2 

All 4 ingredients are available at the supermarket but potentially hazardous   *club* what with airbourne silicates and caustic Soda etc.
 :idea:
having attempted both - I agree with tel, on cost, simplicity and safety, flour and molasses wins hands down on water glass, since they are also available at the supermarket and both ingredients are edible (sort of) before adding the sand.

my jar of molasses was 1/3 Kg and I think I've still got enough to do me for the next 5 years  ;D

Bez


----------



## ShedBoy (Jul 19, 2011)

Cheap and easy is always the go when it comes to a hobby. I am also going to give foam a go for some one off stuff. Once I get some new wheels made for Davey I am going to give some iron a go. I have a small crucible which should hold up to the heat, it is made of some special refractory material, only one way to find out. That is why we have drain holes in the bottom. Roll on Monday so I can go home.
Brock


----------



## tel (Jul 19, 2011)

And they smell like ANZAC bikkies while they're cooking - do you won't get hoisted out of the kitchen.


----------



## bezalel2000 (Jul 26, 2011)

ShedBoy  said:
			
		

> Bez a copy of them safety rules would be great.
> 
> Brock




Hi Brock

Sorry I took so long with this one. 

 I have just posted that safety rules I use in the foundry.

There may be the odd thing or two one could add to the list but this basic list has kept me out of trouble for a few years now I hope it helps you stay safe as you get started.

http://www.homemodelenginemachinist.com/index.php?topic=15199.msg156451;topicseen#new

I saw your flasks - I don't think they're going to wear out any time soon.
Mine are all wood - the sand is heavy enough without adding steel to it :big:

You'll get a huge buzz when you pull your first casting out of the sand. I know I did.

Bez


----------



## xlchainsaw (Sep 5, 2011)

sand is always a problem .....people are so keen to get started with casting that they forget about the sand..... good sand just cant be found at a drop of the hat!!! it takes months to make!!! in small batches ...a bit at a time....about a third of a bucket to a mix. with 4 buckets needed to get a good start....its very frustrating. 


what i do.... completely dissolve bentonite in water to a slurry.... add common white silica sand ...stirring and adding sand till it looks like brickies mortar...... then... its laid out in the sun or on a bbq hotplate and completely DRIED!!!! this can take weeks..... once dry....sift through a very fine metal tea strainer..... now you have dry sand coated with clay..... next you need to re wet mix with abit of water....i use a stirrer in my drill... keep applying dry sand till moisture is correct......leaving to stand overnight and re stirring the next day is perfect........ making sand is a slow labour of love but once made.    and people think that by "just asking" i will give them a bucket or two to get started!!!!!!.... not likely...my sand is a valued asset!!! and in time alone would be worth about $100 a bucket!!


----------



## Rocket Man (Nov 4, 2011)

Go to your local foundary they throw sand away after it has been used many times. You can also buy some good sand from them. The problem with the old used unwanted sand is it won't vent the hot gasses but it still works pretty well for small home castings. There are lots of different types of sand some are good for extreme detail. Do a Google search for Green Casting Sand several places sell it.

I have two 5 gallon buckets of free sand I got from a local foundary that does bronze and aluminum castings that I have been using for 20 years. The local foundary gives it away by the truck load lots of people use it in their garden. I would be afraid to eat anything grown in sand that contains metal.


----------



## /// (Nov 4, 2011)

I have been searching for a recipe too, haven't used my furnace in years.
Found this recipe for a sand called K-Bond. I have not yet tried it but hope to in the future.

It is apparently similar to Petrobond, in that it is an oil bonded sand, but it has the advantage that it is non-carcinogenic
Pretty good advantage I reckon!
It also appears to have very high detail judging by the photo's in the second link.

K-BOND 1
K-BOND 2

Edit: note that the recipe calls for _Bentone_ clay, not Bentonite
Bentone bonds with oil, Bentonite with water.


----------



## Franklin (Jan 31, 2013)

Hi Bez

I am a volunteer working in Vanuatu and interested in hearing more about your experience there.  I am also working on a casting project and would love to be able to use local casting materials.

Frank Sanders
[email protected]


----------



## gocy (Jan 31, 2013)

bezalel2000 said:


> Hi ShedBoy
> Study carefully foundry safety and commit to following it. (I follow a list of foundry safety rules let me know if you want a copy.)
> Bez


Can i have a copy?


----------



## ELM6061 (Feb 1, 2013)

gocy said:


> Can i have a copy?


gocy, go to the top of page 2 of this thread, first post is by bezalel2000, hit the link and read the new thread. All the rules are on that page and worth reading if nothing else. I think they may make it to my shed wall or door.


----------

