Supporting > Casting
Petro Bond Sand
fidlstyks:
I am wondering if many on here have used this sand. I was at Lancaster Foundry Supply in Pa and bought a barrel full. It was suppose to be brand new unused sand.
How ever it would not work right. My first thought of course was to ad the catalyst which I substitute with Rubbing alcohol 91%. Still did not work. So I painstakingly mixed 10# batch experiments. I ended up with 2oz of oil, 1 cup of clay and 2 plus tea spoons of Alcohol. Mixing and screening each 10# batch. This took me 2 days.
I remeber from past use that it likes being packed down a few times to make it work well.
Does one add alcohol at every use? I noticed on a big 350# mold about 10# gets pretty hot so assume it evaporates out . I added a couple of tea spoons to this burned area.
I down loaded a formula to mix new sand. I bought a broke bag of the clay at a discount and plan to mix more new up. Am wondering if anyone has a good formula. My download calls for 2 quarts of synthetic 2 cycle oil. Seems like alot.
fidlstyks:
I am always wondering what makes things tick. I use to think Petro Bond made alot of smoke. But today after pouring a flywheel I started thinking that oil does not burn without oxygen? So once metal goes in, it does burn out the sprue, but then it suddenly quits burning. It must be because it burns till the oxygen is gone from the mold.
Opinion ?
littlelocos:
I've been using Petrobond sand I purchased on eBay (petrobondforsale) and have been very happy with it. I use steel and aluminum flasks and have gotten in the habit of separating the two halves after the pour and carefully separating the black, burnt crust from the fresh, red sand. It almost sounds like the barrelfull you got at LFS may have been old stock. Sounds frustrating.
Todd.
ART:
I have been using Petro Bond casting sand from LFS for over 20 years, and have not had any problems. I use the same sand over and over slightly retempering it when needed with a little alcohol and 2 cycle smokeless oil. Yours might have needed further mulling. When the weather gets cooler I let the Petro Bond container set in the sun for a while to get the mix warm. This seems to help distribute the liquids. Mine does smoke after casting, but not a lot. Good luck.
Art
ART:
Was the barrel you bought "pre mixed" somewhat red in color, and ready for use? If so then you might be mixing a lot more "catalyst" than you need with the sand. If the mix was dry than 2 quarts / 350 lbs. sounds about correct. With your test mixes 2 ozs. of oil to a cup of sand seems too high. The ratio will be about the same as the alcohol. Do you mull your Petro Bond or just riddle it to retemper ?
Art
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