Re: wax burnout

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Posted by James Michael Marr on July 27, 19100 at 14:42:58:

In Reply to: Re: wax burnout posted by bruce paul fink on December 05, 1997 at 21:27:58:

: : I have an easy inexpensive solution that works fine.

Get a 55gal. steel drum, (make sure no hazardous or flammable materials were in it before/soap/food etc.is good ) then cut 12inches from the bottom, use the 12 in. bottom for the water pan, buy three pieces of 1/2 inch metal conduit, 2 lawn mower wheels, a large coffee can, and 2 ft wide by 1 in thick by 50 feet of 2300 deg F refractory blanket $50.00, buy a 500K BTU propane weedburner (Northern Tools) $50.00 Cut the conduit (equally spaced)and raise the top half of the barrel about three feet above the bottom piece of the drum. cut a hole in the top of the top drom piece and fit the coffee can with the top and bottom cut open. Line the top part of the 55 gal drum and coffe can with refractory. use stainless steel bolts. Use ceramic shell mix and dip refractory in it and use to cover the bolts. Make a bracket to hold the weed burner torch. All this can be built in a day, and works fine. When I use it, I roll it outside and use a 20lb lp propane tank. Safety clothing, face shield, respirator, gloves, etc. I have a 1/4 inch stainless rod that's made into a hook and hangs from exhaust vent into heating chamber, I use 1/8 in stailess welding wire to secure the piece (temporaily) to the SS hook. I fire up the torch and have the cup facing down, with the focus of heat on the cup area gradually moving up the piece. I glows red hot. ( before placing in furnace) I drill 1/4 in holes strategicaly in the ceramic shell piece to release some of the pressure of the wax and patch afterwards. The wax falls to the water pan below, I have some small pieces of refractory blanket that I use to grab the "Hot" finished dewaxed mold and then place them in a 500deg f oven to cool down. Most of the carbon is burned out of the molds, and with the flash burnout of the weedburning torch, there is minimal smoke. The torch is a little loud though, sounds a little like a small rocket. Then a seperate barrel is set up next to the bronze melting furnace to reheat the molds before the pour. This is a two step process but eliminates the smoke issue, and you can make repairs or store the pieces until ready to pour, (batch casting, batch dewaxing) Hope this helps? I have a patent application pending on this design.

: : To:

: : artmetal@wugate.wustl.edu

: :

: : Maybe a worse one, which I worry about all the time, is wax burnout

: : from a lost wax casting. I don't know what the big foundries do. I'm a

: : little foundry. Anybody know?>

: : Bradley Sanders

: : This is a problem for everyone, Brad. It sounds like you have the

: : idea, though to reduce the smoke to the minimum. An improvement on the

: : steamer is an autoclave, like the kind used in hospitals for

: : sterlization. The higher pressure minimizes cracks in the investment

: : due to better thermal transfer. You might be able to pick one up cheap

: : from a used equiptment place.

: : Another thing to do is make sure your gating allows for complete wax

: : drainage.

: : One thing we are doing, with ceramic shell, is to immerse the dewaxed

: : shells into the furnace at around 1500 F. The nasty fumes are there for

: : about 10 minutes, but there is no smoke.

: : I had a call from a reporter from Southwest Art Mag the other day

: : writing an article about foundries and he asked me if there was anything

: : special about my foundry. I said like what and he said "Well like a

: : foundry I interviewed that has a smokeless burnout furnace."

: : Wow, I didn't figure my customers would really give a damn about

: : smokeless burnouts. Anyhow,it's all in the technique. Proper gating

: : and high temprature immersion so the smoke combusts.

: : We have 99% wax reclaimation, most of the 1% is lost when we clean the

: : cups and it's not really burnedoff but thrown away due to contamination

: : from shell material.

: : Mark Parmenter

: : Bradley, Mark and others,

: : We use ceramic shell and we de wax with a venture ceramic kile burner on

: : the end of a 1/2" pipe with a ball valve for gas control. Great hot flame,

: : easy adjustment and good flame/heat control. Burnout over a 1/2 of a 55

: : gal barrel. Hang the shell from a swuivel snap hook on nichrome wire.

: : heat the cup first and move upward so there is an escape area for the wax

: : as it melts. Have been using sprue wax for the main sprue and aome of the

: : vents as it melts at a lower temp than victory brown thus making a good

: : vent for the wax. Just did 32 shells and had only one crack a bit. We

: : repair all cracks, drain holes breaks (shell fell over and broke off an arm

: : and a leg. Just used a bit of gauze and patck material and stuck them back

: : on and worked great!!!) using the R and R slurry, some of the zircon, some

: : silica flour and a wee bit of the fused silica. It works great. Takes the

: : heat, redaily available, and cheap......

: : Once the shell are burned out, we put them into the shell kiln and fire

: : them. Very little fume or smoke if the flame is adjusted (more oxygen

: : while the wax is fuming so it burns, then less air once the wax is gone to

: : fire the shells. Have a friend (Lorin at Bear Paw Foundry in Scottsdale

: : AZ) who got a cremation oven and it has all of the afterburner stuff on it

: : to give smokless/fumeless waxy burnouts. He got it for cheap (not normally

: : available, but maybe you have a friend in the business who is updating

: : equipment as Lorin did.

: : I love this shell talk and other foundry discussions.

: : John

: :

: : John Dach and Cynthia Thomas

: : Maiden Metals

: : > Well we definitly are a small foundrie, also Santiago Chile is a big city sited rigth in the midle of hughe mountains , in winter we have one off the biggest smog and polution problems off the world and when it comes to low budget WE SHOULD BE THE KINGS, anyhow when we started to cast we simply burned the shell in a ceramic gas kiln , this work fine but smokes a lot unless you use a BIG kiln in that case you can increase the air suply an get allmost no smoke the cons are that the expense on gas to fire the big kiln this should work if you have enoff pieces to de wax but if you wanth to do a few pieces it get expensive, affter a few trails we set up a open bottom kiln abougth 1 meter high and 1 meter wide on top of 4 steel leggs we use ceramic fiber ( 15 cm, ) and with a

: : sliding top ( like the ones in old morgan kilns ). It takes short time

: : to get to 900 c. we introduce the piece from the top as quikly as

: : posible ( so the temp on the kiln wonth drop to much ) and waith, after

: : a minute or so the wax will flow true the open bottom to a water filled

: : canister, the burnout will take a few minutes then out and in with

: : another. this produce allmost no smoke, visible at least, then we take

: : the kiln off the leggs and place it on a brick floor and use it to fire

: : the pieces, we can fit many at one time. We dw wax usually around 10

: : kilos of wax and do pieces up to 40 kg . for smaller loads the same

: : outfit in a 200 lt. steel barrel works perfect. I think is a matter of

: : size.

: : roberto

: : > We have 99% wax reclaimation, most of the 1% is lost when we clean the

: : > cups and it's not really burnedoff but thrown away due to contamination

: : > from shell material.

: : I have never atemped to re use the wax again because I dont now the

: : procedure to do it, we considered the wax inexpensive and simply dont

: : bother to reuse it, but if is simple will do it for shure

: : How do you handle the red hot shell?? I think we are not doing it rigth

: : How big, can one piece be cast??

: : IF we wanted to do something big in one piece?? solid investments??

: : When we startted we atempted the casting with a mixture off clay and

: : gippsum with bad results Can this sistem be use with a solid investment

: : like the jewelers use in centrifugal castings?? the jewelers investment

: : is EXPENSIVE to do big pieces we should need something cheaper??I am

: : shure you got many Wich one should I considered???One that I can

: : manufacture myself???

: : For big pieces ?? iff the pressoure from the metal is the limit How

: : abaugth ,de wax and then over the shell build a solid investment

: : reinforcement?? How abaugth shell de waxed and put together affter it?

: : Then reonforce with solid investment???

: : We think we should atempt to recover the zirconio flour (much more

: : expensive than the wax ) The procedure to do it??

: :

: : Any coments shure will be aprecieted Sorry for the spelling

: : regards

: : A very long time ago when the world was young and I had never heard of

: : autoclaves and such I built a simple dewaxing system that used a boiling pot

: : and a sheet plastic tent. The steam alone, without, pressure did and

: : adequate job on the molds. I think that a few test runs would give the

: : system a good name.

: : Mark is absolutely right about designing the gating system so that the wax

: : doesn't form any pockets that will expand without a drain.

: : Hank

: : Hank Kaminsky, Sculptor

: : > At one time we considered an aouto clave it was incredible expensive How

: : much a used one will be ??

: : Expensive. I do not use and autoclave, but I wish I had one. I dewax at

: : around 500 degrees. All my shells are in stainless steel baskets, that

: : are toploaded into my kiln using an overhead crane. We dump them in at

: : this temp.

: : I have never atemped to re use the wax again because I dont now the

: : procedure to do it, we considered the wax inexpensive and simply dont

: : bother to reuse it, but if is simple will do it for shure">

: : If you get your wax too hot it is useless. Otherwise just melt it and

: : strain it to get out shell material.

:

: : How do you handle the red hot shell?? ">

: : See above. Baskets. We burnout, lift them out and pour in them. Never

: : touch them.

: : How big, can one piece be cast??

: : As big as your kiln.

: : IF we wanted to do something big in one piece?? solid investments??

: : Why do you want to do that. If you blow it you loose everything.

: : When we startted we atempted the casting with a mixture off clay and

: : gippsum with bad results Can this sistem be use with a solid investment

: : like the jewelers use in centrifugal castings?? the jewelers investment

: : is EXPENSIVE to do big pieces we should need something cheaper??I am

: : shure you got many Wich one should I considered???One that I can

: : manufacture myself???

: : For big pieces ?? iff the pressoure from the metal is the limit How

: : abaugth ,de wax and then over the shell build a solid investment

: : reinforcement?? How abaugth shell de waxed and put together affter it?

: : Then reonforce with solid investment???

: : There are many formulas for solid investment. Just remember you have to

: : burn them out for a LONG time. Like days for big molds.

: : Formulas for investments aboud, but are usually 2parts of refractory

: : type filler like fire clay, ceramic grog, old molds, etc(How about

: : ground up shells?) and one part plaster. US Gypsum sells different

: : plasters for metal casting, too. A thinner mixture is put on first

: : (face coat) and then backed up with the thicker mixture. A wire

: : reinforcement is needed as the molds are very weak. Burnout at 1000 F.

: : If I remember about 4 hours per inch of diameter. You must bury the

: : molds in dry sand. I think plaster investments suck. Bad surfaces,

: : alot more attention to gating (more) and much more prone to coldshut

: : and inclusions. Also crappy control of directional cooling. Why do you

: : think they invented ceramic shell?

: : We think we should atempt to recover the zirconio flour (much more

: : expensive than the wax ) The procedure to do it??

: : None I know of. See above for mixing into plaster investment. I use

: : mine on the driveway. I also do not use zircon, only fused silica.

: : Congratulations on your Herculoy melts. Did you figure out your

: : fluidity problems?

: : Mark Parmenter

: : My steamer consists of a square pan in the bottom of a cabinet,

: : with

: : a grill below it, and a burner, just like in an ordinary oven. The pan is

: : filled with water. The wax which is evacuated sits on top of the water.

: : When

: : it is cool, it becomes a skin on top of the water. I cut it out, remelt it,

: : and pour it through a cloth filter. Good as new, then.

: : I don't know if this procedure would work in an autoclave. Anybody

: : know?

: : Bradley Sanders

: : When I was a student the sculpture teacher set up a trip to a place on Long

: : Island called the Roman Bronze works. They were imigrant Italians who did

: : solid investment molds because no one had dreamed up the shell casting

: : method yet. They poured huge sculptures in one pour sometimes with two or

: : three crucibles pouring at once and they did repairs with gas welders when

: : there were problems. Joints were accomplished with what they called "Roman

: : Joints" which were mechanical connections using tapered pins to secure

: : parts. Jack C Rich and Malvina Hoffman wrote books that used pictures from

: : their workshops. I don't know if they are still around.

: : The proceedure went something like this:

: : A wax was built from the original with glue molds and laboriously painted

: : layers of wax. Later they switched to "Black Tuffy" for molds. Once a wax

: : was assembled the cores were installed. Core mixture seemed to be a

: : combination of new plaster, "luto" which was old burned out investment and

: : either grog or sand in equal parts, it was hard to tell. They drove nails

: : through the wax for core pins before the cores were laid in. Core vents of

: : wax rods leading to the top had also been installed before the waxes were

: : finished and these were carefully surrounded with core investment. Once

: : the

: : cores were done the wax gating system was attached leading to a cup at the

: : top. A wall was built of the same type on core plaster around the entire

: : form. It was laid up in coils of this thick slowly setting plaster just

: : like

: : you'd build a coil pot out of clay. It went from below the form (which had

: : been put up on a pedestal of investment with drain wax rods in it) all the

: : way to above the top. The craftman would build a while on the wall and then

: : wrap steel wire around and around the form inside the wall and then pour

: : buckets of plaster and sand (or grog) slurry into the breach between the

: : wall and the form. That was the investment. In this way the entire form

: : with it's core and gating system in place would be covered with solid

: : investment. Once done the mold would be dollied into a kiln for burnout. If

: : it was too big to be dollied they would build the kiln around it and drag

: : over burners and fire it in place. Days of burnout would fill the air

: : around

: : the shop with the smell of burning wax but that was accepted in the

: : industrial neighborhoods of those days.

: : Once burnout was complete. (They would hold mirrors up to the vents and

: : look

: : for signs of moisture) the still hot investment was exposed and a wooden

: : wall built around it and packed with molding sand. The proceedure was like

: : clockwork with the silent workmen clicking through each task. Normally they

: : would chatter along in Italian all day but when the pour was impending they

: : seemed to take a serious tone and get to task. That mold had to be poured

: : before it cooled too much.

: : The period after the pour was known as the "time of madness" since you had

: : to wait until it was cool enough to go after the investment with sledge

: : hammers and break it away from the casting.

: : When I went to southern Spain to get away from the states back in the early

: : 60's I built a small scale foundry in a little town near Malaga. I've told

: : stories about that experience before (the little plaster burner with the

: : burro) but the method I used was basically like the Roman Bronze method. I

: : made my originals in clay and then, since I had no access to flexible

: : material, I made the mold around the clay out of investment material,

: : driving nails into the clay which would embed in the mold and then painting

: : wax into the washed out mold. The gating system was attached to holes

: : drilled into the investment and the the whole mess was invested like the

: : Roman bronzers did. They all worked just fine and recently I was able to

: : buy

: : back two of the Spanish pieces.

: : This is the longest post I've made in a while. It's due to the fact that

: : I'm

: : forced to wait at the home office for my 15 year old to get through his

: : morning rituals at lunch time before I drag him off very late to school. I

: : hear the shower stop running now so I'm back to duty again.

: :

: : Hank

: : Hank Kaminsky, Sculptor

: : Studio: "The Art Experience,"

: : >>

: : We should make a deal with your young'un to be late for school more often

: : Hank. That's a very interesting thing about the Roman Foundry. I have

: : Malvina Hoffman's book lying around somewhere in one of my boxes, and I do

: : remember the photos in it of the foundry.

: : Considering how you folks now do the castings, it's amazing that anything

: : was

: : done the old way, but I guess it worked. Well sure it did, what a stupid

: : statement.

: : Come back for another visit soon Hank.

: : Chris Ray

: :

: : This was interesting to look inside an old foundry and appreciate the

: : advancement of ceramic shell. Now if they could just do something about

: : the wax *aroma*. Scented?

: : I managed to visit the Rodin museum last weekend and noticed seam lines

: : on many of the works, particularly where the arms were attached. Does

: : anyone happen to know why these were left showing? Just *seamed*

: : peculiar. Great museum by the way.

: : Cynthia

: Cynthia...That's been a queer puzzle of mine for a long time.

: When you look at the beautiful pieces in the Smithsonian it becomes very evident that the seams and mold marks and dross and general poor casts that sculptors would generally want to not see... heftily abound. Many foundries where these have been created are noted for their skill in casting and chasing with a family dedication to fine craftsmanship. Therefore it makes me wonder who is doing the castings that are puntuated with hundreds of finely drilled and tapped and pegged holes and pits that have become some of our national treasures. On several occassions I have been called on to explain the markings that seem to appear on the works of museum collections that are beginning to show as rings and indentations that had previously been invisible. I marvel at the skill and patience of the foundry workers that produced the flawed sculptures and their skill at making a bad casting seem better. Had I been the sculptor I can honestly say they probably could have initially pulled the wool over my eyes as well. As the pieces age though ...it all comes out. I'm sure most collectors or critics could not tell the difference at first either...especially if at auction or sale or in the heat of a moment in the initial discovery of the form...or if they were tied to a possible percent commission on the sale.

: Go to the Smithsonian and look up the works of the Orient (and there are others as well). I found the finest, no flawed, superior patina and superior bronze formulas amoungst the sculptures of ages past. The casting skill and finess (as well as the forms) coupled with several centuries of patina absolutely blow my mind. I also wonder why poor seams and castings from our time are held up to levels of genius....

: I've been doing my own sculpture casting since 1961. I know first hand the many pitfalls. I respect those that I find to be my superiors and feel I appreciate others success and genius. I think it's called admiration and love.

: bruce paul fink

: :


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