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Sawdust as Facing Ingredient

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russ57:
By weight or by volume?

-russ

vtsteam:
In casting, ingredients always by weight, at least for me.

vtsteam:
As a follow up, yes the 2% pine sawdust facing sand was successful in giving a much better finish to my castings. Spruce sawdust did not do quite as well, though it did have some effect. I'm thinking that hardwood sawdust might be better than either, and could be used at greater percentage (by weight) since it is denser, and takes up less room, affecting bond strength less therefore (I hope.)

Another thought is that adding dry sawdust to facing sand too soon will cause it to absorb moisture out of the sand. There may be a difference in performance between sawdust facing sand mixed a week ahead of time and sand mixed during molding. This would logically seem to reduce the bond strength of the sand, and increases the ignition time of the sawdust. Something more to test.....

awemawson:
There used to be a spirit based spray on that was applied just before closing the cope and drag. While the mould was still open it was flashed off with a gas torch, burning and leaving a carbon like surface deposit. This was to improve surface finish and didn’t interfere with the facing sand bond.

vtsteam:
Yep, Andrew, washes have traditionally been used for improving casting finishes. but the topic here is experimenting with sawdust in facing sand.

I'm interested in knowing how much and what type and how mixed and when should it be added to optimize. If you are planning to do any sand casting in future with your induction furnace and want to give sawdust a try in traditional greensand, I'd greatly like to hear your results.  :dremel:

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