Newbie here, while I know casting over concrete is a bad idea in case of spillage, that is my available work area. Any suggestions on what kind of covering I can use to reduce risk? A sheet of plywood maybe? I get that it will burn a little, but not worried about a little smoke.
Thanks, aluminum, I have both the chinesium 16kg dual burner furnace and a Gingery furnace I built years ago but never completed.
It's true, you should avoid pouring over concrete. The risk is steam explosion. From my past life, I was trained to view risk through the lense of probability of occurrence and consequence of failure. If there are no people or property at risk consequence is low. Plywood insulates better than one would think and as it becomes charred insulates even better. You may need a dam around the edges to contain a larger spill. I've never tried it but I've been told the fire grade gypsum board is pretty good too. Spreading sand over the concrete is good protection. More depth the better but an inch or two is good insulation. I routinely dumped hot mold sand on my driveway for 8 years now with no ill effects Crucibles are rated with different conventions. An A10 would be brim full 10lbs of aluminum. Crucibles rated in kg are usually referring to brim full bronze capacity. 16kg of aluminum is a fair size pour. More like 35lbs. But if that is 16kg of bronze capacity the equivalent in aluminum is about 1/3 that mass.....more like an A12. I don't promote nor recommend it, but I pour over concrete. 90% of my pours are <15lbs aluminum, and most of those are <10lbs. Occasionally I pour 40-45lbs and can pour up to 60lbs. Small spills <1lb are harmless because the splash is so thin the metal temp drops almost immediately because the concrete is comparatively so thermally massive. In fact you can usually handle the foil splash with your bare hand within a fraction of a minute after it hits the concrete. I don't want to come off as minimizing the risk because there are also many documented disasters. We all need to assess risk by our own terms and in the end it's up to you to decide. For me, in general I think the risk and consequence of occurrence is low with my small pours. However, if I ever dropped or had a catastrophic crucible failure with a large A60 pour, I would abandon the rig and shield myself. I wear PPE too of course. That much aluminum will fan out and freeze fast but still likely be deep enough to concentrate heat. A violent reaction could send molten or semi-molten aluminum airborne along with concrete fragments. If you are not in the way of that, it's damage to the surroundings. My surroundings are rock wall and aluminum garage doors but could potentially set tar shingle roof on fire. I have fire extinguisher and hose at ready. I assess probability of occurrence as low and am provisioned to handle the worst-case scenario, so it's acceptable risk to me. If you are pouring denser high temp alloys like bronze or iron, the risks are much higher. All bets are off on the above and I would pour those over a sand pit. Best, Kelly
I worked in Demolition and scrounged walk deck from projects. They are made up of 1" bar spaced some distance apart with cross ties every 6". They are 2' x 8' and three of them cover an area of about 50 sq ft. I filled them with dry sand and leveled to the grid. This gives coverage for my pouring area and the grid eliminates any chance of creating a bare spot exposing the concrete below. This is a shot of one corner.
My pouring area is Flagstone so I lay down a couple 2' x 2' pieces of plywood to place the flasks on. The invariable spills smoke the wood and I'll flick them off to keep them from continuously smoking.
Sand over pavement was the solution used at the last two iron pours I attended. The sand is spread prior and swept up afterwards as the space is normally used as a parking lot. For my home stuff, 3 lb (1.5kg) small batch aluminum, I make a couple square feet area of firebrick to support direct contact with the crucible and tools and under the small furnace. The flasks themselves are usually still on plywood mold boards, off the ground on work tables, and I check them with a level if needed. I don't do any other covering of the adjacent ground, which are various hardscapes (concrete, blacktop, landscaping rocks). I dump the flasks with castings and hot sand into a metal wheelbarrow or a shallow metal oil drain pan.
Thanks all, looks like a sheet of plywood ftw, our warehouse is in an industrial park, I'm only casting on the weekend when no one else is around, so quick setup is important. Haven't done metal casting since high school, back when they did that sort of thing in school.
Plywood sounds like the right answer in your situation. We poured all the cast aluminum boulder section castings shown >here< over plywood. A couple small spills and runouts and an ingot mold overflow were all saved from hitting the concrete floor that way. The wood got a few char marks on it but I'm sure it'll get used as a floor protector again on any of his upcoming casting days for years to come. David does a lot more than just foundry in his studio so, like you, he needed something that could be set up and taken down quickly and easily. It worked just fine for us You could probably do a little better if you had a dedicated pouring area, but that's not what you're dealing with. It will probably take a LOT of pours to burn up your plywood floor protector so badly you need a new one. Jeff
I got a large metal oil drip pan from the auto parts store, probably 2.5' x 4' and pour on that. It has a lip so that if there was a spill, it should catch it all, but my largest crucible right now is only an A8, usually I am using an A6, so relatively small capacity.
mine literally suggested I go ahead and cast my own Funeral Marker with blanks so she can have the date engraved on it she has given up on me and is quit certain I'm suicidal V/r HT1
