Two Part Core Sand Binders

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Pipescs
Posts: 2194
Joined: Wed Feb 03, 2010 10:16 pm
Location: Lester Alabama

Two Part Core Sand Binders

Post by Pipescs »

Core Stuff

Sometimes, new things, that look like a great improvement are not what they seem.
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When visiting the Cattail foundry over a year ago, Benjamin the owner showed me a core method using a two part binder that is mixed with sand and rammed into the mold. No Gassing and you have about an hour to work with it prior to it setting up.

Sounded good, so I went by the Lancaster Foundry supply and bought the two gallon kit. Came to a hundred dollars plus shipping.

I put it in the fridge in the shop and proceeded to forget about it. It is actually past its shelf life, by a few months, but still appears to work as the cans were sealed air tight and I kept them cool.

In the mean time I had been making cores using Sodium Silicate and a C02 bottle from my sons Paint Ball gun. This after getting a core class one afternoon at Fenders.

Having used it tonight I have made the decision not go down the road of commercial binders

1. Batch Size: At Cattail they make cores in large batches using multiple molds They can mix up a quart and do a hole pile of molds at one time. In my shop I have one core mold for the project at hand. You can only mix up a one off batch as any left in the bowl hardens up at the same rate as the sand in the mold. With Sodium Silicate, I mix up a batch in a covered (throw away) plastic container from Wal-Mart that has a snap cover. After making cores one evening I have come back the next afternoon to find the mix still usable.

2. The Cost and shelf life is not good for a hobby foundry. It is expensive and has a shelf life of a year. Less if Air gets to it. Sodium Silicate on the other hand can be purchased at my local Alabama drug store in Quarts. As far as I have found on Chaski, it will last indefinably if kept sealed. There is a onetime cost on a C02 bottle and valve but these can be purchased at Wal-Mart. in the paint ball department. I believe a refill is around nine dollars.

3. Hard to get. It has to be purchased on line if you live in the back woods of Alabama. I found it could only be mail ordered in gallon cans with Hazmat issues.

4. Set up time The two cores I did tonight have been down there a little over an hour and are not quite ready to pull from the molds. When I made up cores earlier this week I made five while talking to Fender on the phone. After ramming the sand into the mold, it is a simple matter to push in the C02 gas through holes drilled in the core box. Total time in the mold is less than 2 minutes.

One down side I do hear about the Sodium Silicate cores is that they will take moisture if not used soon enough. I have not had this problem. I store them in sealed Tupperware container that I put C02 into prior to sealing.


So for my money and time I will stick with the Sodium Silicate method. May be old method but easy to do without a lot of initial cost.

This is a Sodium Silicate Core.
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Cores from Commercial Binders
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Charlie Pipes
Mid-South Live Steamers


Current Projects:

Scratch Built 3 3/4 scale 0-4-4 Forney
Little Engines American
20 Ton Shay (Castings and Plans Purchased for future)
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