Metal Casting Zone

It has been a quiet page lately so I thought I would share my most recent casting. Inspired by the person on this board who does the little bookend guys.


lost foam figure cast

Looks sellable! Very cool, but he looks so sad.

I can picture where the sprue went.

Hey looking good...
Question: what type mold material did you use on the foam? and is the finished piece as smooth as the foam pattern? ( guess that's two questions) sorry.
I'm the bookend guy,glad to see someone interested in the same stuff.....
Am fixin' to do some lost wax molding next, if you have any suggestions would be happy to hear them.
blindpig

I used the pink isulation foam and painted on plaster of paris. You can see my original foam at the link on my first post. The metal piece is much rougher then the foam mostly because I still have an issue with the burning form leaving behind gas. In this case I am not really fighting it though because I enjoy this texture. Normally I give more vents for the gas and I can get smoother resolution.

I don't know too much about lost way other then you need to burn out really well to get a good pour. I have done a bit and found that to be the biggest chalange since I do not have a good way of doing it other then throwing in in a fire or using a blowtorch.

I like the texture on the little man as well.
Tell you what I've had to do with my little men because of the rather long narrow limbs. The aluminum tends to freeze before filling them completely even with a multitude of vents. After the plaster is good and dry I pour in some acetone ,slosh it around and pour it and the now liquid foam out. May repeat the process again if necessary. Usually allow the plaster to dry overnight before beding it in sand and pouring. Still not 100% but good results more often than not. Thinking about preheating the mold,plaster,sand and all before pouring to reduce the problem some more.
Can't seem to resist trying for 100% success.
Currently making a pattern to use with the lost wax process. Hopefully resulting in a hood mascot for my sons hot rod (more on this later....
Don....the blindpig

This might be extremly helpful. I just lost a big piece to foam gas and am pissed. Did you find acetone to be safe for the plaster? Do you use just regular plaster of paris?

Hey MIke,
Sorry for the lost casting. I've had the same thing happen and learned that I had to just keep on pouring through the smoke,fumes and foam bubbles. It does get messy though (with the splatter and all). I've had good results with the acetone,have to pour it in slosh it around and pour it out. Most of the time I repeat once or even twice.Let it drain and dry overnight,on occasion I blow it out with compressed air (gently) to help it dry and evaporate. Don't think it will bother plaster as it's water based, because of the porosity it takes a while to dry/vent/evaporate completely. There will still be some foam left as a sort of bubble gum consistancy (haven't been to overcome that problem yet),but it burns out with the melt and may still give gassy like stuff with the pour but much,much less.
The plaster I'm using is quick dry ( 10 to 15 minutes) powdered wall spackle. Comes in many different sizes at Lowes or Home Depot etc. Fairly cheap, mostly used by sheet rock hanger type folks to repair areas that need a little help and drys quickly so they can get on about thier business ( not wait all day for it to dry etc.). I'm kinda using it like they do just mix about what I need apply a thin coat and let it dry,rinse out brush and mixing equipment. Repeat in a half an hour or so and let it dry over night. Generaly do the two coat thing again with another overnight dry. Then the acetone treatment as above.
Hope this helps,
BP

wow.
I am glad you told me about the acetone. It did a great job of melting out the foam. I am not sure if I got 100% but it looks pretty good. Hopefully there are not any spots that were hidden behind hot glue plugs. As a cool bonus I can tell exactly how much metal I will need by measuring the amount of acetone it takes to fill the space.

I typically use plaster of paris but this time I tired the wall spackling stuff. I did a thin coat with a paintbrush and then made a 2gallon bucket of the stuff and submerged the whole mold in it. This is much more like how I had done lost wax in the past. I also added 5 airvents made from bendy straws. Hopefully this will be the one that finally works perfect.

Overall I would have to say that lost wax is the way to go to get good detail and clean pours but I don't have a good way to burn out in my home set up... actually I don't really have a good way to melt metal either.

Hey Mike,
Sounds like you are on your way,hope you have a sucessful pour.
The only lost wax casting I've done was finger rings,used a single burner hot plate with a metal pie tin on it (to catch wax) and a clay flower pot lined with aluminum foil turned over on it ( almost forgot the wax/plaster mold inside).
The piece I'm fixin' to try is much larger,thinking about using a metal pie pan with a clay pot again but heating it above the exhaust flue pipe of my furnace. I'm also kinda toying around with steam casting to insure a complete fill 'cause the mold has a lot of thin long areas( just itiching to freeze)...Might be over kill but dang I hate losing a piece...
Later

steam casting sound like more trouble then I would stick my head into but interesting. I tend to preheat my molds but I never know if it makes much of a difference.