Rough Casting

I have made green sand moods
The sand is sieved using a fine sieve and the kitty litter is also sieved and adding water.
When casting Alliminum the item when removed from the sand the casting is rough.
What can I do to make the casting smooth.

 

Can you post some photos of the casting, what kind of aluminium alloy did you use?.

 

Without pictures it's all guessing. But course sand, or too much moisture will give the casting a rough texture. Normally it will still be shiny in these cases. If it's cloudy you might be getting oxide in your casting.(too much air in the furnace).

 

I will post a photo as when I attempt my next casting.

 

Greg
I have used graphite and alcohol. Put it in a spray bottle and spray your cope and drag when finished spraying use a torch to lite off the alcohol. The graphite will not hurt your sand and give you a nice finish.
Nelson

 

Thank you.
I will try that as that is my problem

 

And if the aluminum is too hot you'll get a rough surface. It should not be red when you pour.

 

What is the desired temperature of the alloy for casting

 

Greg,
Coating of green sand with graphite (acidic nature) is right approach, to have better surface finish.
You can use fine zircon powder (acidic nature).
Aluminium is acidic in nature. It reacts with coating material (if its basic), leads to rough surface finish.

 

Most aluminums should be poured above 1,200F, but each alloy has an ideal temperature. If you have an unknown alloy start with 1,250F to 1,350F.

 

Thank you