What is the "right" amount of moisture for greensand?

Me, head smack? Never! ;-)

I am very very pleased with my muller. It gets the job done a 5 gallon bucket at a time while I am putting away the previous 5 gallons of sand. Some rolling action and some smearing action are pretty much unavoidable on a 4-inch-wide wheel. I can see the stream of sand as it exits the wheel and the inside 1/3 portion is "torn" every 1/4 inch or so much like a steel bar tears of you try to bend it too much. The outer 2/3 is a smooth ribbon of compacted sand. I am thinking the tearing action is a result of the speed of that portion of the wheel not matching the speed of the wear-plate of the tub. That would result in smearing and tearing of the sand ribbon. Whatever, it works well.

Presently, I am working on making a chute to cleanly direct the sand as I dump it into a 5-gallon bucket. Right now, as a work around, I am catching the sand in a tray and then transferring to buckets. That is OK but would be a lot nicer to skip that step. (I keep my sand in 10 five gallon buckets as the buckets have good seals on the lid and I don't lose moisture that way.)

 

Jeff, my 5 gal lids were purchased at my local "real" as opposed to Home Depot or the like hardware store. The Home Depot lids I bought were absolute crap. The ones I have now look similar but are better plastic, don't split easily like the HD ones and have a good gasket. They cost about the same as the crappy Homer buckets. So, might be worth shopping around.

 

I use lots of hydraulic fluid, etc. on the farm and the lids have an excellent seal but are very difficult to get off. I guess it's time to save some lids and make a lid lifter tool. Hmmm, lost foam opportunity?

 

This may be totally obvious, but....the five gallon pails of lubricants that I buy have the lids held firmly in place by means of a "zip strip" that binds together all of the maybe dozen or so lid segments that snap over the to pail upper lip. Peel off the zip strip and the now-individual segments are much easier to pull away from the lip and disengage. Disengage five or so segments and the lid lifts off relatively easily. Maybe everyone else knew that since they were five years old or so, but I just learned that when I became interested in using the buckets for storage of sand. Guess I am a slow learner. Not to say a "can opener" to disengage the segments wouldn't be handy, though.

 

After the zip strip is off, I find it very difficult to get the first few segments to release even when pushing on the center with my knee. Guess I'm a 175# weakling.

 

Tobho said: " And I may need to build a chute of some kind for my muller too; I discovered it wants to dump sand everywhere when I tilt it over... Of course much of that was coming from between the top and bottom half of the drum, which has since had its rubber gasket installed and been tightened down, so maybe it's not as big of an issue as it seemed at the time."

I think I mentioned I was in the process of designing and building a chute for my muller. Well I "glued" together a prototype out of 16ga steel that works pretty well. I have put a few buckets through it and I get about 95% of the sand into a 5 gal bucket. I will refine this in the not distant future, but want to use it a while to determine what tweaks are needed. Here are a couple pics to give you an idea what I made.

 

More likely you are getting very good quality pails with robust high strength lids---better than the pretty good ones I have.

 

Back to the original question about moisture content of green sand. Yesterday I noticed the sand I had mulled (sand that I have used multiple times in the past) was not behaving right---it tended not to pack into the mold quite as cohesively as normal and then a layer dropped out of a flask when I inverted it. This was something I had not had happen in some time. As I was mulling I had a sort of voice in my head saying that the sand was feeling a little dry, but I debated that back and forth. Finally after the sand dropped out after a second try I gave up for the day and took home a couple samples of mulled sand to moisture test by baking it out in the oven. I gave it 4 hours at 250F and weighed samples and then baked it four more hours with only a tiny decrease with the second bake. Because the weight was stable after the second bake, I felt satisfied that I had gotten all the moisture out.

I am using 100 mesh olivine with 5% Southern Bentonite clay and 3% sea coal for cast iron.

On bake out I found I had, indeed, gone a bit dry as the moisture content in each sample was right at 3 %. For my methods and molds, about 4% is a target number. So having not molded in a few weeks caused me to drift from my target moisture despite trying hard to remain consistent.

Just mentioning it here as one person's experience. Will fire up the muller this afternoon and have another go...

Denis

 

And I did remull the sand adding just a few ounces of water per 50 pounds and was rewarded with sand that behaved itself nicely! Yay! Interesting to me how small the moisture content difference can be and still make a big functional difference.