Does anyone spray the mold cavities to set the sand? If so what do you use? I've been using spray paint applied about 3-4 times, allowed to dry between coats. After pour it peels off in a sheet from the sand and seems to give a smoother finish than just the facing sand. Just curious, any opinions or tips appreciated ,,,, Thanks,, John ...
where are you local to? so we can take wild A$$ guesses about your sand, and what metal are you pouring,? I'm going to take a WAG its a bronze of which there are about 6 Gazillion varieties, Now spray paint in no way is a mold coating, so perhaps do a little research on mold coatings or washes , that is what you should be using, in a natural accruing green sand you can get some great surface finish results with very simple mold washes https://maritime.org/doc/foundry/index.php#pg44 has one, a couple of other members here have done research on washes with great results from available items like fireclay V/r HT1
I'm in SW NM USA. The sand is what we call blow sand, it's very fine sand and adobe clay, no rocks, pebbles, trash etc. I have to hand mull, let it set a day in an airtight container. It sifts easily, rams tightly. I use the spray paint to lightly coat the mold cavity and set grains to help prevent any detachment while handling the completed mold prior to casting. I had one do just that, ruined the cast, no problems since spraying. Also after casting the paint will peel off the sand in a sheet making it easier to reclaim the sand if need be although I have an unlimited supply providing the sand is accessible, snow, overly wet from rain, etc. The metal is from commercial potable water meter casings. It has a light bronze color right after casting, turning a golden bronze patina after time, polishes to a high sheen. I called it red brass for want of a better description but I think it's probably some type of a bronze alloy.
now that is some good info water meters are indeed a red brass that color means it is probably a newer lead free alloy, the older ones are often 85 5 5 5, and will stay a reddish color , you need some clay in that sand , southern bentonite . adobe clay will be western bentonite, you need a mix of both for really good green sand as far as mold washe go watch this video and take notes Sandrammer has forgotten more then I know on the subject V/r HT1
Very interesting video and thanks for the info on the bentonite difference, I'm smarter now. I'll get some southern bentonite and add some. Thanks again John,,,,
Just a quick post to show how the spray paint peels off the mold halves, the paint from the cavity turns to a black powder and will just brush off the casting.