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Hello there.A fellow Welshman welcomes you to MEM. Sadly " dim siarad y cymreag " I'm pleased to read you're into casting, feel free to ask for any advice.Cheers Graham.
Hello again.The term " greensand " is sand tempered with water to help bind the grains to form around the pattern. Obviously the amount of water is critical, too little and poor binding too much and the mould can literally explode from the steam that's generated.I'm using " Mansfield Red " with some Bentonite milled in. This sand is now well over 30 years old and still gives perfect results.The " squeeze " test is a method of judging the temper, take a small handful of sand and tightly squeeze it. Relax and if little to no grains have stuck to your palm then the sand is wet enough to bond but dry enough to use safely.Pleased to read you're into IC engines, been my interest for many years. Cheers Graham.
How smooth a finish do you have on the patterns and what are they finished with. Also are you dusting the patterns to stop the sand sticking?J
Hello.We're a friendly bunch here, I'd really like to address you personally.Regarding the use of Talcum powder it does have a tendency to grab at the water and go sticky, I'm pretty sure there are some suppliers still out there selling small quantities of " parting powder " ?Foundry sand is different to " other " sand insofar as the grain structure is very irregular, it kind of locks to itself the Bentonite adding to this. You can also make DIY Gas bonded sand using Sodium Silicate ( egg preserver ) .... Mix dry sand and SS together to a texture not unlike your present mix, mould the sand around your pattern then using some Carbon Dioxide gas inoculate the sand. This is a similar process that's used on a much larger scale in modern foundries. Gas bonded moulds rarely have breakage along parting lines and, sand grain size dependent, can produce really fine definition.Cheers Graham.
Some oil based paint can take a long time to go hard even though it feels dry so this may not help, a modern waterbased quick drying one is probably better.You could also try an oilbound sand which won't need anything mixing in or water added, these people do a lot of small amounts so not too pricy to try things out. The small amount of casting I did in the past was with petrobond.https://www.artisanfoundry.co.uk/?cPath=29&sort=2a&page=1
Hi Ilionellis,I know nothing about foundry work, but do want to say, Welcome to the forum!Kim