Laziness

[Rasper]

At the end of a long day I got lazy, and now I am paying for it. Rather than a nice clean casting I have one with lumps all over that I am now cutting off with a cold chisel. And there is a section I have to cut off, re-cast, and weld on; as far as I can tell, all due to my not wanting to remove the sheet metal cylinder from the investment after I had sealed the burn out kiln with mud and had begun firing. I forgot to remove it before hand.



I told myself that some people keep the metal flasks on during burn out; in fact, some people use heavy iron pipe flasks. Well, obviously they burn them out for a longer time than I did this one, because there was still moisture in the investment when I poured. Ugly.

I did get a useable casting though. So all was not lost.



The problem was mostly localized:



I will cut this area off, make a new wax of that part, fit it to the casting, invest the wax while still mated to the casting, burn it out and pour. I figure that should give me a good fit that can then be welded.

Richard

[Harry]

Bummer Richard. I know you are at a place in this where you have certain expectations on every casting and a lot of investment prior to the pour. Always one more thing to learn though and I thank you for posting this as it will possibly save someone else down the road having read and learned from it.

On another note, wow man, thats an awesome looking sculpture. You always have great looking stuff to show off. One of these days I want to meet up with you when you are at your studio in So Cal, maybe have a couple beers and just shoot the sh**.

[Jammer]

That seems to be a common problem with large bust type castings. I'm taking a small Bronze Casting class in Columbus to try to get some pointers on investment and casting Bronze. I don't know if I'm learning much, kind of a bunch of Arsty Fartsies. One of the instructors did a bust and had the same problem, a lot of bubbles and rough casting at the top of the pour. The head and face came out great but the top of the torso was pretty rough. He said he didn't burn it out enough. They use a kiln, I'm not sure what their schedule is, but he said his bust should have been in there for 5 days or more, because of it's size.
Tonights the last class. I'll see if my casting came out.

[Harry]

That brings up a thought I have had before Jammer on a few castings where I had a problem at the entry point. Anyway my thought was a sacrificial entry point, if you have a place where it can be easily removed just extend the casting so the problem ends up in the part being cut off. Guess it is much the same idea as using a Bob just before a part but in some larger pieces I find I still get a small amount of turbulence right at the entry gate between the bob and the part.

Richard, I am curious as to why you dont use ceramic shell for your castings? Just seems to me like everything about it is easier and less prone to problems in the casting and with what you have invested in the mold up to the point of investing seems like any cost difference would not matter. Just like to know the reasoning here as I dont have much experience with either.

[Rasper]

There are several factors that determined my using the solid investment method.

Where I live, way down near Guatemala, nothing is available but basic stuff—stuff such as plaster and bricks, which I use. Everything else I have to buy up in Mexico City and ship down here.
I invest infrequently, so I don't want to have to maintain a slurry pot.
It's hot down here year round. I have a devil of a time with the wax getting soft while I'm working on it. I keep the waxes in a tub of water and only take them out for maybe 30 minutes at a time to work on. Handling them in multiple dips in slurry would surely be a problem.

I have a good article by a now dead sculptor on this question. I am going to post it in a separate thread so those who are interested can read it. It's not long.

And . . . I have decided to re-cast the whole thing. I realized I was mostly just being stubborn. A good trait at times, but not always.

Richard