Don't judge me on this one... actually roast me. I need all the advise I can get. This is my test 'patina' piece I use for cold casting. I did the artwork for a 'demo' example for another piece. So I figure while I am designing some crosses for my first commission, I really need to work out all the kinks of Lost wax shell casting bronze. Here is the piece with a cup and some sprues I just hand made. My wax pre-shell And here it is hanging with my first layer of slurry and silica on: My garage is about 110* f right now so we are drying in the basement. What advice do you guys have?
YAY... A thread I didn't start. Looks like nice artwork, wish I could see it a little closer up. Don't feel too bad. I am shelling now and have to run the process over night too due to the heat here in Texas. I wish I had a basement, but will be adding AC to my garage this winter when I won't need it. My first question is how thick is the thickest part of that? I noticed the back of it wasn't hollow. Your spruing setup looks good to me. With lighter setups, I let them dry hanging upside down like you have here. As they get heavier, I flip them over and have the cup support the weight. I see you have chosen what looks like a coat hanger to bury in the wax cup. I don't have to tell you by now, hanging onto that thin piece of wire royally sucks. I made some 5inch long hooks out of 1/4" steel rod. They can be seen in my videos. Makes life much nicer when you are hanging onto the end of that thing with 15lbs hanging off the other end. First coat, I read do not force air, do not try to speed up the drying process, do not allow bubbles in your slurry before you apply silica, do not pass go, do not collect 200dollars. I use a chip brush and light compressed air at the slurried wax to blow excess slurry off the piece. 2nd coat, same deal with the fine 50/100 silica and take your time. After the piece is dry, the temperature of it will arrive at the room temp. This is another way to know it's dry. You must control the temperature of the wax AND slurry during this entire thing. If you don't or allow the slurry to thicken like I did, you will get a cracking during the drying process between coats. See fox video part 1. I keep my slurry in the AC and the dipped waxes in the AC also. Now at coats 3+ you may add a small fan to blow on the pieces to accelerate the drying. The big question is always how many coats? You are looking for 1/4" thickness minimum and the shape of the piece will also dictate how many layers are enough. I shoot for 6 or 7 layers. What's your plan for Dewax? There is a difference between dewax and burnout. Dewax just rids 90% of the wax from the shells in the most expeditious manner to prevent the shell from cracking and burnout fully vitrifies (think turns the shell to almost glass) and rids the insides of foreign material. I'm a 2step kinda guy myself and here is why. If you just heat the hell out of it and head straight for bronze, good luck with that. You won't get the chance to fully inspect the shell for cracks and make necessary repairs. You can even patch a fully vitrified shell! Mix up some slurry and add some silica into a paste and patch away. Twice is usually enough to fill drilled relief holes. When you run the shell back up to 1700 before pouring, this will cure your patch and you are ready to for metal all at once. By now, I'm sure you've seen my experiments with boil dewax. And you've seen my failures with flash fire. If you are going to flash fire, I would recommend you drill a few 1/8" drain holes on the back of that art piece. You can patch them, but keep the patch dry and dont let liquid get inside that evacuated shell. I've made that mistake and dunked a dewaxed shell into a bucket with the holes still open. Cost me my fox and now I have to do another if I want one for myself. Shell is wonderful stuff, If it's going to turn to shit, it's during the dewax process. I would like to construct ANOTHER furnace for dewax if I don't stay with this boil out method. I want to be able to preheat a closed up furnace. THEN, lower the floor, place my shell on it and raise it back up into the chamber. This will allow the shell to be instantly bathed in nice even heat and allow the wax to flow out the bottom. Thus hopefully preventing cracks. I believe the cracking comes from uneven heat from my harbor freight weed burner. :-(
Thanks for the advice, I'll answer questions after my kids are in bed... Here is the original: Here is a copy in gypsum plaster Here it is gold leafed: Next is bronze...
That's it. I QUIT. I'm copying chinese dogs and this guy comes rolling in with a sculpted sheep on a bed of roses sporting a cross and a waving flag. Why couldn't I have been blessed with some inkling of artistic ability instead of potential for starring in a skin flick????? Yeah, it needs to be in bronze, save the gold leaf for some greek laurel leaf stuff. Used here, it cheapens the piece.
That was the best comment ever! I almost couldn't hold my phone when I read it. Just FYI it is called an 'Agnus Dei' it is a very common symbol from ancient Christianity. I have one that is way larger that I made for the same chapel that I am making the crosses for, it is already installed and is cold cast resin-bronze Maybe I should re-do it for the sister once if I figure out bronze casting. When I made the large one, I actually cast 2 in the resin-bronze and the second one just was ordered for a second chapel. Q. How thick is the thickest part of that? A. The thinnest is 1/4 of an inch. At the thickest it is just under 1 inch from the nose to back of the piece. Q. The big question is always how many coats? A. I was planning on 2 coats with fine mesh and at least 3 more coats with thick mesh, then evaluate thickness and if I want to add fiberglass anywhere or another layer. This is my first time making a shell... so maybe six or seven. Q. What's your plan for Dewax? A. In the making. I was debating the boil method since the piece is so small. With the Bas-relief I can drill lots of little holes in the back... but want to risk none with this one. I was going to go with upside down and use a torch I have had for years for melting roofing tar and grasses.
lmao... 1inch is pretty damn thick. Shrinkage is always in the back of my mind, not in my pants. I'd like to think your fat sprue and the cup is so close, if it tries to shrink, hopefully it will pull from there. I was talking to the guy that does the BIG bronze nautilus shells online and he tried boil out. http://www.alex-kirkpatrick.com/sculpture His was a failure, but blames it not working on geometry. I can see that. If you notice over in the thread on this current piece of mine, you'll see that I angle sprues and vents backwards to what is the commonly accepted method. They point towards the cup for this very reason. (like yours) I've never had a problem with bronze not getting to where it needs to so my goal remains to get the wax the hell outta there before the shell blows apart. Personally, I would boil your piece out, let it dry for a day and give one coat of slurry and silica and bring it to 1700 for the pour. You'll be a believer after you try it. If you do, have a roaring boil going, straight to the bottom with the piece and gently move the piece after a minute or 2. When the wax chunk of the pouring cup floats up, swish for 30seconds more and pull it. It's a fast process.
Ya never know he might be right. Maybe that's the history behind the BP. I think your wax looks good. The sprues look viable and I think its gonna cast well. Just be sure to keep it cool right until you dewax. Don't leave it sitting in 110F for 10 mins while you fix the burnout chamber or the wax will expand from the heat and bust the shell. I just did that on my eagle and it wasted a lot of work. When you are ready get that sucker straight into the hot burnout chamber straight from the basement
Well I botched this one up good on the pour. I had a lot of problems with my shank. I had modified it so it is adjustable, and it was to low to hook onto the crucible in a side pour orientation. Had to put the crucible back in the kiln, and adjust. By the time I went to pour the bronze was to thick, plopt one thimble size piece of bronze in the shell before I realized it. I put the shell and the crucible back into the kiln. It will take 2 hours to get back to max temp, I wonder how screwy the shell will get with that bronze in there. I am in experimental crazy mode. I think this is a major learning experience, but it will be a huge failure. My melenocoly is at a severe extreme today.
UH, that's not good. You might try INVERTING the shell inside the kiln and hope like hell the bronzes flows outta there. If it doesn't find it's way outta there, the sheep my get an extra nose. I use a piece of rebar to test the temps of bronze. Dip it in, should come out pretty clean.
I'd cool down the shell, and use a piece of steel rod to poke the blob out. Then put the shell back into the kiln and heat it up again for the pour. Or try shake it out. The blob will either block a sprue or probably cause a casting defect in the piece if it went in deep enough. It won't remelt and fuse with the liquid bronze.
Maybe... but you know how it can stick to shell upon breakout. It's some tenacious stuff sometimes. I have some shell that comes off almost clean and other times, forget it. I wonder why that is? He might get lucky and save the shell. I think he's got a mold so failure would suck, but not be the end of the world.
I don't know either. I have the same issue. Sometimes the shell burns onto the metal and is very difficult to get off. I think the hotter it is poured the more it sticks and burns in. I hope for the best otherwise its going to be either a recast or grind out and tig weld the defect. Did you end up casting the rope yet?
