No More Lurking Around

Yo What up,

I've been casting/tinkering for about four years now.Living in Kansas City, MO working in IT. My primary casting purpose is creating bronze/copper/aluminum sculptures or fixtures for furniture projects. I am very much an amateur but will attempt to participate in anyway I can.


My current projects involve:


1) Building a large electroplating cell ( 25 gallons).

2) Clothes Dryer Tumbler/polisher Conversion

3) Converting my propane burner into an oil fueled one

4) Clay based Ceramic Shell Slurry Formula

I just finished my “burn out kiln” a few weekends ago



I know full well the futile nature of trying to “DIY” a ceramic shell recipe since I’m nearly positive I’ve spent more money on materials, trying new things, when I could have just bought a 5 gallon SuspendSlurry by now. With that being said, I aimlessly persist after my white ceramic whale. I’m sure I’ll break down and buy some one of these days but until then this is what I’m working with.


Here is the current iteration of my formula:

Procedure

1) Prepare Silica Acid solution

- Solution A - Mix 30% by volume HCI with 70% Water

- Solution B - Mix 25% by volume Sodium Silicate with 75% Water

Slowly combine solution A into B while forcefully mixing to form Solution C

- Mix 10% by volume Glycerin into Solution C

- Mix 10% by volume Fumed Silica into Solution C



Mix approximately 1-4 hours (this is all going to depend on how much gelling action occurs)

- Cheap continuous mixer prototype


2) Prepare refractory Stucco (Mix by volume)

- 5% - Silica Flour 350 M

- 10% - “Kiln Wash”

- 25% Fumed Silica

- 60% Molochite 200 M

Dip – Stucco – Repeat!!

Again, really looking forward to seeing all the interesting things everyone has going on! Shout out to Tobho Mott for directing me here - Cheers

 

Good Call with the uploads - I messaged you over Reddit a few weeks ago

 

Welcome to the forum.
So the big question: How well does it work?

Pete

 

I'll make a post in a few weeks - This is my first formula using the acids, the others were no better than if I had used sand(and often much worse ha)

I anticipate some minor tweaking but after this round of trials, if I'm not happy with it I'll probably breakdown and buy some of the real stuff.

 

Welcome. Good luck on your experiments. SS lasts 2 years as long as you open and mix it once a month. When casting metal, failure is around every corner. You'll find out after spending many many hours that homemade slurry or furnace refractory is false economy. Ask the guys how well their grant thompson furnaces worked out for them. I wish I had a buck for everyone of those that show up here trying to poor boy a furnace together. Same goes for using cheap dollar store candlewax.

 

I would like to see some more photos of your burnout kiln. Are you also using this to dewax too? Are you collecting your wax for reuse?
I've been doing the water boil out for my ceramic shell and I have way fewer cracks than I ever did doing flash fire dewax with a torch.
My wax recovery rate is now probably 90% or better! When wax costs almost as much as my bronze, I collect every little bit for reuse!
After I dewax, I go into my old electric cat piss kiln for burnout and preheating prior to pouring metal.

The hardest part I have found so far is when dewaxing, to prevent cracks, it almost requires complete even heating across the entire shell instantaneously! (This is why the boiling water works so well) This can be a tall order trying to shove it into a preheated chamber that has the ability to capture falling wax in a waiting pan of water. Barry Luke Builds on youtube has a pretty clever furnace for this. He preheats the chamber, opens the bottom doors, loads the shelled waxes through the front door and closes that. The wax instantly starts raining out the bottom and into a tray of water. After the raining stops, he closes the bottom doors and raises the temperature to casting temperature for pouring.

I have some ideas for something similar, just no time to build it, so I keep boiling for now.

 

I primarily used Steve Mills Designs when building the furnace [Link to PDF]



As you can see its wood fired and I exclusively work with foam based models so unfortunately I don't have much input on wax reclamation. I've only fired it once and was able to sustain 2100 range temperatures for 3 hours.

Also Jason - You are 100% correct that attempting to replicate CS formulas is a false errand - I simply enjoy messing around with the chemistry and since surface finish/defects are not of chief importance, I can get away with more. I'm planning on using all my PTO the week after thanksgiving to really sink my teeth into my two formulas.

 

Ahh.. SO let me get this straight. You want to run ceramic shell on lost foam??????

 

The nature of my sculpture work necessitates using foam and I understand ( somewhat ) the risks involved with cracking during burn out via foam expansion but I've had some good luck using acetone and smart design considerations to downplay it.

 

Then you really needed to see the Buttplug thread. I theorized Ceramic shell for foam work, BUT without using acetone. Turns out, you can use ceramic shell and just send the piece through the kiln. The foam will cleanly burn off the kiln and leaves nothing behind. Leaving your shell ready to receive metal. Kelly here does non complex car parts in foam and coats them in a similar slurry minus silicas. He uses the metal to burnout the foam. He has to bury his stuff in sand because his coating offers zero strength to home the metal back.

To the point, ceramic shell works great for lost foam and you dont have to rely on the hot metal to eviscerate your foam. The COE of foam is probably close to zero. The shell should hold foam back easily.

 

I too very much doubt that expansion would be a problem. Foam is highly compressible as it's volume is mostly air and other gases, solid polystyrene weighs about 62 lb/cu ft, polystyrene foam is between 2 and 8 lb/cu ft.
BTW, when I refer to foam in the context of any type of lost foam casting, I'm talking exclusively about polystyrene foam (aka: styrofoam), other types of foam like polyurethane or polyethylene foams are likely to cause problems, incomplete burn out, residual ash, etc.

 

I havent met a foam yet that will survive 1700degrees. Even if it leaves some ash behind, a fast water rinse and its gone.

 

Question, only slightly off topic, have any of you lost wax guys used foam armatures? By which I mean roughing out your shape in foam and then applying wax to the foam to finalize the details.

 

Sure! It works fine... But I think I know where you are going. Let the foam take the brunt of the pressure increase instead of the shell. Hmm.. Never thought about it like that. I use all sorts of goofy crap to take up useless space and save a buck or two on wax. But using something that will burn up during dewax/burnout is pretty smart. For all intents and purposes, you could ball up some newspaper, tape it up for stability and wax over that. Anything that will burn up is fair game. With proper shell, it's no big deal to cool it back down for a water flush and reheat before pouring.
I'd be a little more skeptical with an old slurry or a homemade brew that may not like going cold to hot a couple of times. Suspendaslurry doesn't seem to care how many times you reheat it from what I've seen.

I'm looking forward to seeing what Treehouse does here. Anyone that puts that much work into a kiln outside in the yard has my attention!

 

YUCK! I'm gonna need a longer cord for my kiln. City limits far enough?

 

As you might imagine many of my attempts have been failures i.e. significant casting defects, incomplete casts and shell failures. I'm currently working on trying to incorporate that "gooey mess" into the piece itself but good info nonetheless. I've been mainly using EPS and you are right on the money with the fragility during shelling. I've taken to using 3Ms 77 spray in conjunction with anchors connecting the pieces ( toothpick/wires) but overall trying to keep the amount of connections to a minimum.

I have some pieces I encased in clay ( 2in thick walls) that have been drying for about 3 weeks now , that should be ready for the kiln. I'm very excited about this ancient inspired method - here's hoping the slower drying results in a full mold vs the pile of clay dust that resulted in my first, hasty firing