It’s been over a year since I last fired up the flowerpot furnace. A multitude of factors have got in the way from weather to needing to work on the gates to being too busy enjoying other things.
I switched from briquettes to a bag of “instant lighting” charcoal. The latter seems to work ok but is very smoky when first added to the furnace. I’ll switch to hardwood charcoal next time which seems to be plentiful in my local shops. The melt was started off with offcuts and scrap from the previous melts, once a reasonable pool was formed a mix of aluminium was added, mainly disk drive cases but also some cans and swarf.
I bought myself some Petrobond sand last year as I was not happy with the results from the hand made “green sand” and have finally gotten around to using it. The Petrobond was easy to use in that it did not fall out of the flask, formed nicely around the patterns but did not stick to the patterns. The mold did not collapse when it was assembled and the surface finish was better than my previous results.
One difference with the Petrobond is that it will smoke and blacken where the sand touches the hot metal. I’ve quizzed the people of the HomeFoundry and Casting group and they say that I don’t need to worry too much about this but it’s worth removing the large lumps from the sand before re-using it.
Here’s some photos of the greensand vs Petrobond sand results.
As I had the furnace running, I thought that it would make sense to melt a second batch. This I poured into open mold to make an ingot and a blob which can be used to start of the next melt.