Casting Wax - ArtMetal Live Chat


Log of April 23, 1998 ArtMetal Live Chat
edited by Bruce Fink

Casting Wax

Host: Keith Farley, Metalsmith, Artist

Guest: Bruce Paul Fink


Jock D. - So, are casting waxes hard or soft and are they anything like machinable waxes?
Osan - Jock: some are very machinable, others are very gummy
Bill - There is an incredible variety of casting waxes available
Jock D. - I've got a piece I carved in canning paraffin that I'm scared of losing by screwing up the casting process.
Osan - Jock: why are you scared?
Jock D. - One of carving, bad previous casting experiences. Low threshold for pain.
Keith - Ok, let's get started. Bruce and I will be attempting to provide some guidance to this session.
bpfink - One of the things I'd like to cover tonite is the great variety of waxes and "other" model media that are also great for casting
Keith - Just to get an idea where we might best take this chat session, are most of you involved in sculpture or smaller casting processes such as jewelry?
Osan - Jewelry sized for me
bpfink - All suggestions are open and maybe between us we will be able to hone in on some new possibilities. I hope that any of you with specialized waxes in your experiences will add these to our discussion also.
Jock D. - I'm into 1 to 2 pound bronze castings.
bill - My experience is jewelry, but I want to go large!
enrique - I'm all ears... or eyes. Don't know much about waxes or casting. ga
bpfink - We can cover all sizes from extremely small to as big as a mold will tolerate in your mind
Jock D. - So, how bad did I screw up using paraffin?
Osan - Jock: who says you screwed up? Paraffin can be OK for certain forms.
bpfink - The biggest difference isn't in what wax it is as much as in what works. As long as it burns out clean and doesn't do odd things to the mold in the process it can be superiorily valid.
Keith - Paraffin is really soft and gummy but can be used to develop some basic forms.
bill - I would think that it would be difficult to get a lot of good detail in
Osan - As a general rule, the harder the wax, the finer the level of detail one can achieve
Keith - Paraffin, however, I've never had much success in getting to accept much surface definition
Jock D. - Paraffin, It was terrible to work! Don't try it!
bpfink - Paraffin has a molecular structure that could be compared to slate if in rock. It shears and is often hard to work with as a slight oil like layer stays between the harder slab like molecular body connection layers. It burns out fine but does do a bit of expanding when it melts.
Osan - Jock: I've tried it and I agree it is not good. I really like Ferris green. I'm still having no luck finding large sheets of hard wax..
Keith - Jock, what sorts of objects are you trying to achieve?
Jock D. - I've just got one oversized key waiting to be cast.
Keith - And it doesn't require any particular degree of detail?
Jock D. - Its about 4" long - 3/8" thickest mass,
Osan - Jock: sounds like a job for a nice hard wax. Where do you get this?
bill - Osan, have you tried contacting Kindt- Collins Co. @ 216-252-4122. They make sheet wax for the industry.
bpfink -As you may know by now my main favorite wax is simple Victory (hardness name) in a Microcrystaline wax. It runs about $1.30 to $2.00 per lb. and comes in 10 # slabs in 50 lb. boxes. You may want to forget the wax Jock and go to a simple sheet of styrofoam plastic. Know that sounds odd but I will try to explain. You can accurately cut it to any thickness on a band saw, carve it with a razor knife, emboss it with carving or routing or heat shrinking or adding wax to it's surface and modeling (as well as a thousand other ways)
Keith - Bruce, do you use Victory Brown by itself or do you ever mix it with other waxes to achieve particular properties?
bpfink - Victory by itself most of the time Keith but also 3 others to vary hardness or melting temperatures if the need arises. We can include specific addresses and compile them at the end of this session along with a repeat of any others people put up for more details with any personal preferences.
Jock D. - So, my original question, Is casting wax anything like machinable wax? I know casting waxes need to be low ash. I'm not sure about machinable. The reason for my question is because we have a lot of machinable wax in the shop for testing machine setups.
Osan - Ferris blue, purple and green are all machinable. Sticky wax, OTOH, is not. Neither are injection waxes, but there are exceptions.
Keith - Jock, I do a fair bit of lathe turning of carving waxes. I suspect, but cannot swear, that these would be pretty much equivalent to what you are calling a machining wax.
Osan - Jock: that is a good casting wax. Cheaper than from the jewelers' suppliers too :)
Jock D. - Great!
bill - some of the machining waxes have plastic in them
Keith - Ferris is the one that I generally use. It carves great and accepts unbelievable amounts of detail.
Osan - Perfect purple is a great buildup wax. It doesn't get gummy after melting.
bpfink - I did a larger than life sized detailed figure two years ago of a 1930's portrait photographer with a large box / bellows camera in realistic detail. The camera segment was entirely made from Styrofoam and cut out on the table saw, band saw, hand carved with razor knives and with the copied antique hardware scanned from the original camera, drawn out and then cut from sheets 1/16 inch thick and appliquéd. Hot Victory wax was used as the glue along with wood toothpicks which helped hold the styro pieces together in the planning stages. The picks are left in the model to burn out with the wax and styro. Unlike most waxes... Styrofoam can melt or dissolve before expansion in the mold can cause cracks so flashing from that is eliminated.
Jock D. - How and in what material was the figure cast? Was this piece cast from a plaster mold?
bpfink - The figure was modeled in plaster and wax and styrofoam separately and a polyurethane / fiberglass mother mold made so it could be hand wax dipped, painted and slush cast with the hot, liquid Victory wax and then backed up more for strength and thickness with a harder 2 part rosin : 1 part ceresine wax mixture. The camera tripod legs were also machine cut and sanded styrofoam... made same way they would have been made if in wood. There are many different densities and porosity's of styrofoam so don't pre assume they are all alike. The entire figure with all accessories is now cast in bronze and stands in front a studio at 4900 N Milwaukee Ave. in Chicago. The resulting figure can be seen at my site at
enrique - Here is another view the full image.
Osan - Bruce: where do you get the large quantities of microcrystaline wax?
bpfink - I get the wax from: Premier Wax 3327 Hidden Valley Drive, Little Rock , AK 72212 501 225-2925. It is a petroleum wax made by BARECO Products and is generally sold in 50# quantities though I usually buy from 600 to 1000 # at a time. Roughly $2 / lb.
Osan - thanks
Keith - So Bruce, are you saying that the components of this piece were made using styrofoam as opposed to wax?
bpfink - Exactly Keith. The term WAX to me here relates to the model that is used to make the final molds for casting. It's requirements are that it can be a media to be manipulated to the desired outcome AND that it can then be removed via burning out in the mold. This means that it certainly includes all waxes that burn out clean but also includes many other media such as plastics. I have even worked originals in Balsa or soft woods where the wood grain may be important to the surface detailing. Also papers or plant material as well as many other media that are then burned out with a top to bottom vent through the mold and by adding the necessary oxygen to accomplish a clean removal and blowing out ash. I'll just avoid that direction part of the discussion right now.
Jock D. - I've designed machinery castings up to 18,000 pounds that were cast in iron from styrofoam patterns but I think this is a different process. I'm assuming the styrofoam AND wax is burnt out prior to casting, as opposed to the iron castings where the styrofoam is left in the mold.
bpfink - That type casting Jock depends on a light density foam so it can vaporize with the hot metal flow. What I'm usually using is slightly heavier as these are usually 'Lost Wax' burnout's so the pattern is fully removed in the kiln before the metal is poured. I mostly use plaster base investments so a burnout is required anyhow but with porous sand type or green sand molds you can pour directly on the styrofoam and a little wax could also gas out through the walls at the same time (accompanied with lots of smoke, flame plumes and smells). This isn't a favorite of mine though as the control is less than I require.
Keith - Bruce, what is the determining factor which steers you toward using wax as opposed to styrofoam?
bpfink - Whatever media aids to give me the form I'm searching in the fastest, the most accurate and most economical way and is the most fun to do at the moment... wins.
Osan - Bruce: does microcrystaline (MC) wax exhibit a grain?
bpfink - No grain at all Osan. It's tacky enough to stick to itself when room temperature but has many qualities that will be determined by the temperature of the media so that is a controllable item.
Keith - And the wax additionally serves to camouflage the styrofoam porosity?
bpfink - Right Keith, though the wax surfacing isn't really necessary if you use a styrofoam with a very fine porosity (like whipped cream fine) or if you seal the larger type pores with a flash of heat. That's my normal system as I shove the carved sheet in an open kiln, furnace, or fabricated metal air duct with a gas burner at the lower end at 600 F for about 5 to 15 seconds and that slicks and seals the surface pores without altering the central shape.
bpfink - The name microcrystaline comes from the molecular type structure that is a non grain body with inter linking molecular adhesion similar to bees wax. This microcrystaline is a petroleum product and cheaper. Comes in clear (like the sealer on some paper milk cartons or drink cups), amber or brown.
Wray - Bruce the Styrofoam allows you to construct basic shapes quickly, and then you add wax where it is needed to create finer details. Is this correct?
bpfink - Yes Wray. You can get styrofoam with a very tight, dense pore which looks more like a fully whipped cream surface. Hard to even see any pore so almost anything will fill it. Also comes in the denser weight type they cover flat roofs with (which is hard enough to also nail the roofing on).
bill - Bruce , Do you carve the styro with a hot wire?
bpfink - Bill... hot wire sometimes but usually hot Sally Knives (butter knives gotten from the Salvation Army Store @ 15 cents a piece and re-ground, bent, shaped and heated on a burner (like 5 or 6 in a row) as well as any wood shop standard tools like table saw, band saw, razors, sanders, heat guns, sand blasting, etc. Most all my molds for bronze casting now are plaster based investments so I can mix many model media as long as it can be burned out or somehow removed.
Jock D. - How do you work styrofoam models?
bpfink -Here is a JPG of an 8 ft. diameter styrofoam piece (only part of the whole sculpture) that was air grinder / hand carved using course carbide router bits after laminating up 2 inch sheets and first routing it out as a round pancake form on a lath...the lath was non existent but just an 8 ft. round table, the router was on a firm rigged stick assembly and did the traveling around and over the form using a plywood guide to regulate the curved heights. This was modeled for later investment casting but would also work with other molds systems. John Dach will be adding a chat in the near future on ceramic shell casting. Have corresponded with him and know it will be very good
John D -Hope it is as good as you keep saying Bruce!
Keith - Hello, John and welcome
Jock D. - Hot wire is what my pattern guys do 90% of their work with.
enrique - Here is one of Bruce's images. Bruce will describe.
bpfink - The first is the finished bronze figure. Camera , tripod, accessories box, 8 x 10 slide film holders were all styrofoam in the original model ready to be invested.
Jock D. - Cheap and efficient!
bpfink - and I could make the box and camera faster this way than if I also made a rubber mold and tried to cast them in wax so no molds were needed and when a second model is needed I just make a second camera, etc. Sounds repetitive but up to a limit it is sometimes quicker to make a second or third model from scratch than to make a rubber mold to reproduce the waxes for more castings. Does this start to show how your key could be made quickly Jock?
bill - Bruce, you pour the molten metal on the foam, right
John D - I believe he would invest the wax
Keith - Bill, I've seen aluminum cast by pouring right into the styrofoam. I expect that it would be doable to do the same thing with bronze.
Wray - Bill, the styrofoam vaporizes during the burnout phase, same as the wax.
Keith - But since there is wax involved with his Styrofoam, it seems like it might very well have to burn out.
John D - Again, I think Bruce invests the foam just as one would invest a wax.
bpfink - Right John. Only difference is that it can take less spruing for the removal of the wax since the plastic is nearly removed before the piece even goes to the kiln. Amazing what a can of lacquer thinner can do poured on and into a styrofoam sprue prior to the burnout kiln's work. Makes the investment 50% or such empty before the burnout even starts... so it's also another way to eliminate flashing which would be caused from a normal wax expansion situation.
bill - At St. Louis (ABANA) I saw iron poured into the foam in sand...
Jock D. - Sand casting can be done with DRY sand using styrofoam patterns!
John D - If it is the correct type of foam, a direct or open casting can be made.
Keith - Bruce, how do you go about eliminating the wax or is it so insignificant in quantity as not to be a problem?
bpfink - I burn out. You can pour metal right on the foam with a very small amount of wax if the mold is a green sand or set sand that is very gas porous but I do a standard burnout as I add so many other things and don't use the sand molds that much. Plaster based molds ALWAYS need a burnout to eliminate the mechanical AND chemical water content.
Keith - John, would you say that there are particular sorts of forms that better lend themselves to the use of styrofoam than to wax?
bpfink - The sand may be called green sand when it's used for direct pouring on the foam. Then it's a combination of sand, small amounts of powdered clay and a touch of water to make it stick together. others have a rosin or oil and catalytic binder mulled with the sand to help it hold the shape and these are firmer and usually superior in surface holding of detail.
Jock D. - Your new car's fancy intake manifold and most of the other casting were made from closed mold, dry sand, styrofoam pattern castings.
John D - Met some folks a number of years ago who cast foam almost exclusively, not pre burning it out but allowing the metal (Al) supply the heat. Got interesting and varied textures from the burning foam.
Jock D. - Its not "green" sand when used dry in the new processes.
John D - Keith, I don't really know except that I read A LOT and there is always mention of particular types of foams with different properties. As to foam vs wax: yes for rigid requirements, smooth, even thickness flats. I currently use wax about 99% of time.
Wray - The automotive industry is using a lost styrofoam casting to create thin wall precise aluminum engine castings.
Jock D. - They mold the styrofoam. Then glue up hollow sections like manifolds that used to be very complicated to make cores for. You can often see the molded foam texture in the parts!
bpfink - The foam that is a bead type is often visible when cast. It is often used as it is easy to pre cast into molds with steam that expands a sand like grain of plastic. Like coffee cups. Great for production quantities. I most never use this kind but go for the fine pore and machiability of the sheet kind. By putting up a wooden guide on the band saw table you can cut a sheet or taper as fine as a piece of paper and also as thick as the sheet itself.
Osan - Bruce: this is not directly wax related, but I was wondering how the cores of bronze sculptures are made. What are they made of?
Wray - Osan, good question.
bpfink - It's all wax related Osan good question.
bpfink - The cores can be made at the same time as the investment , or before... so the wax is even modeled or worked over it , or after... the other investment is cast and is holding the main outer surface body in a precise position before the center is filled.
Osan - Are any of these statues I see of multi-piece construction and welded/brazed together afterwards? I'm just at a loss as to how they get hollow with no apparent openings.
Keith - Bruce, I assume that you need to secure the core to the outer mold. How do you go about doing this?
John D - Tig welding is so very useful for holes and "gluing" pieces together.
bpfink - The core is PINNED to the outer mold by simply putting some pins through the wax. These stick out to both sides so they will hold the core in place.
Keith - Are the pins of a particular material or does it matter?
rlow - And then you weld them up or what, Bruce?
rlow - The holes left < I mean >
John D - Keith, one way is to push wire pins through the walls of the wax for the core and the shell/investment to grab on to. For ceramic shell, I often make a number of holes in the piece so the outer and inner layers of the shell are "attached" at these sites
bpfink - The pins I use are sometimes stainless steel and then when the piece is cast you cut them flush and either leave them if in an invisible area, or knock them through and weld or peen the hole shut (put a dot of wax on the model where the pin enters so there is bronze cast as part of the body to peen into the hole later, saves mini welds). I also use pins made of the same metal I'm pouring so they act as anchors until the new hot metal is in place and then disintegrate and become part of the body metal. That's a bit riskier though and there are always a few stainless one used to assure the stability as they can melt once the metal flows in and you are risking the chilled metal to hold the core in place.
Osan - This is way cool. Learn something new.
rlow - Could possibly melt too soon?
bpfink - The bronze pins require a little risk and a lot of flow planning so the metal will be solidifying before there can be a shift. I almost always have 2 or three stainless steel pins also
John D - Yes correct, especially if "students" are not being careful about burnout time/temp. Lost a kiln full of shells when a "student" was totally miss reading the pyrometer and left the burnout on full tilt for 1 1/2 hours (normally 15-20 min.).
sherry - what is the core made of?
bpfink - The core and whole mold for me is normally 50 % plaster and 50% sands from fine to slightly courser. That's a generic formula but close to normal use
Wray - Bruce, on a large casting such as Mr. Charles, what are the wall thickness that are favorable?
Osan - How is using pins of similar material riskier? Is it because they melt away and the core might shift?
bpfink - Exactly Osan. Often I get away from the pins if one end of the mold to the core is open and I just put in a good rebar or two. These figures are life sized so rebar is valid.
John D - I use stainless steel pins now as I have had problems with bronze pins softening and allowing it to shift.
rlow - John- They would tend to soften during your burnout?
Keith - At what point do you begin to think about developing a hollow mold rather than casting a solid piece?
bpfink - Most always Keith. The mold being open is easier for other reasons also. The inner core can be removed through the same opening, as you don't want to leave it in there unless it's a rare case (bronze disease possibilities, rare but can happen after many years). I think hollow first as the cost of an extra 30 or 100 lb.or more and the attendant shrinkage, etc. makes it easier and cheaper than not to do it. They also get too heavy to handle easily later unless you conserve.
Keith - What do you consider to be maximum thickness when casting bronze, Bruce?
bpfink - The max. is again based on need and savings and final weight. I've had 3 inch thick in the feet of a full figure where they were going to have to support a a cantilevered body but I like 1/4 inch better every where else. That also made it possible to drill and tap for 1 inch dia. stainless bolts for the anchoring.
John D - Bruce, I too try for 1/8 to 1/4 max. wall thickness. If an arm/leg/neck and the hole in the center will be too small for the shell materials to go and out well, I cast these items solid too. This is one of the advantages of investment, you can get it in
Keith - When you say fine sand in the investment, just how fine are you thinking of? Like the sand on a really fine sandy beach or more like the size of pool filtering sand, or sand box type coarseness?
bpfink - Sand fineness varies from a fine flour type / mixed with up to a grit like sugar near the mold surface / but within a 1/4 to 1/2 inch gets as course as window screen thickness and then for the rest is as course as 1/16 inch. The whole mold has more strength if treated like a 'concrete mix' with a variety of grains mixed with the plaster. (The sand I use most is common BRICK SAND sold for mortar mix. It's about $185. for a 14 cubic yard truck load delivered and is then hand sifted for the inner mix needs. Can't get cheaper than that.)
Wray - Bruce, do you erode the plaster core away with a sandblaster, after the casting is completed?
bpfink - What works quickest. Mostly just knock it off first, then sand blast using that same sand that has been sun dried and window screen sifted. It doesn't harm the bronze surface that way. For core removal a long 1/4 inch rod with a whiplash end on a drill is great. Even an air hammer on the metal cup or an under side area will vibrate a lot of it off..
rlow - John- What is your max. burnout temp??//
John D - I generally try for no more that 1500 F. I do not have controls on the furnaces so they have to be watched. We burn out small investment castings at 1350-1500 F for jewelry too, but these go for a lot longer depending on can size.
rlow - John- I cast jewelry and used to always burn out @ 1150 -1250. Now I hold at 900 and get better results.
John D - rlow, interesting. Cynthia is the main brains around here for jewelry, and this is how she has been doing it for years. Has worked for her. Lots of ways to skin the cat huh! Cynthia uses a lot for the farris green/hard wax and burns these out for cast
sherry - rlow - that's what I usually do, ramp up to 1250-1300 then down to hold at 900 until ready to cast.
Keith - rlow, I also take the temperature to between 1100 and 1200 degrees. Higher temperatures seem sort of pointless.
rlow - Yes, john I understand. I think it is all a matter of works best for you. I had consistent results @ 1150, but now use a different casting machine and the largest flasks.
Keith - Then I bring it back down to lower temperatures, depending on the mass of the piece I am casting.
rlow - I don't ever go up past 1000 F and try to stay at 900 maximum.
Keith - The thinner and more spindly the areas of the piece, the higher the flask temperature I find I need. As the piece becomes thicker and bulkier, I tend to lower the flask temp and occasionally will cast at room temperature.
rlow - As long as the flask looks white, you understand?
Wray - Bruce, you seem to model the originals in everything including wax?
bpfink - What ever works Wray. I included some of these tonite as they stretch the limits of what most think of as working in wax. This next one is also a lost "wax" burnout casting but the "wax" was many other things... I did this one nearly 29 years ago.
This piece is 8 feet long and was cast in nearly 350 lb. aluminum. It was done in 1969 as a parody on the pending Supersonic Transport proposal that was then in question to be built. It was called the SST or HERE COME THE BOYS and was a commentary on the colossus of the airways.
It was represented by four of our ever popular American cowboys flying like the late / great superman. Each clutched a dearly loved object from the many aspects of the present life style and offered it out for all to behold in remembrance of our Apple Pie, Green Stamp, Hamburger-Fries heritage. Together they lead the way for a bevy of 80 cows carrying briefcases and soaring above an exhaust vibration that booms to the ground and reflects up while affecting in some small way every earthly object that happens to be cohabiting in the path, near the path, or surrounding the path of the magnificent new SST
Wray - Bruce, where that one now?
bpfink - overheated... melted down in '76.
rlow - Bruce- I wish you had some close-ups of this . I would like to see it. It's all in the details, anyway!
bpfink - The main body of the cast was one piece and was made by filling balloons with plaster based investment (as a series of cores) and then arranging them while soft with wax on them and also pouring urethane foam over them. They were pinned with stainless pins in a hand drill so they go in easy and hold them in position when the foam piece gets burned out.
rlow - This why I enjoy this so much, Bruce. Sharp idea!
John D - Bruce, you are so versatile in your use of materials.. I feel like I am a stick in the mub vs. you, as I use wax from molds almost exclusively.
John D - I also don't type very good either!!!!!
Keith - Bruce, does the wax again act pretty much as a binder of other objects?
bpfink - Not really just... binder yes but a way to detail shape surfaces as well. The cows were very small at about 1 1/2 inch long. They were all cast from a single silicone rubber mold
rlow - Did you TIG weld all of it together or what, bpf?
bpfink - Not TIG but cast as two huge segments and Mig welded those together. The kiln was built in place over the invested 8 ft. x 2.5 ft. x 4 ft. high piece making it about a 9 ft long x 3 ft wide plaster based investment mold and the cast was done without moving the mold at all. The kiln was built under and around and over it, later removed and sheet metal wrapped around it and then damp sand was packed to counter any liquid metal pressures as well as to help assure the lower wax drain holes used during the burnout where now plugged positively.
Keith - I assume the silicone mold was used to make multiple waxes of the cows?
bpfink - NO not multiple waxes... multiple low melt cast cows in the final metal itself ... In addition the briefcase handles were all stainless steel welding wire wound like a spring and then cut into separate circles and fit into the silicone mold for each cast. (One was cast in with the original wax of the briefcase and then one was refit into the silicone mold for each metal cast. Made it a strong simple thing. did about 15 cows per hour casting in metal from the one mold.)
Keith - So, what metal (or was it a metal) were the cows cast in?
bpfink - The metal was a low melting pewter type / zinc, tin , antimony alloy so could be poured below 500 F. Cows in the same metal and the precast briefcases were hung around the cavity of the cow neck so it became integrated with it also ... kind of like the old ship in the bottle thing/
Keith - Glad to hear that you weren't attempting to pour bronze into a silicone mold? Pretty smelly territory, that!
bpfink - Here is a detail from the front.
rlow - How long did this piece take you ,bruce?
bpfink - The piece took most of 9 months working nearly 80 hr. a week and was quite a political stir back then... Have you heard this last month that the Super Sonic Transports are not going to be rebuilt once they fatigue... Guess they finally got the gist that costs of commercial operation would be too absurd, the shock wave they leave limits use to over water, has more guts than thinks. The final body of the aluminum cast was treated like normal and buffed, polished and then painted with transparent motorcycle lacquer based paints (after a special clear adhesive prime coat). It rationally seemed to be carnival time so I treated it like that.
Keith - Bruce, digging more into the waxes, what sorts of sprue waxes do you use? Round, square, otherwise, or do you find that it makes a difference?
bpfink - The spru waxes aren't wax very often either and the shape definitely makes a difference... ga
Keith - I'm not sure I follow . . .
bpfink - I cut from 3 to 6 foot long strips of styrofoam on the table saw into approximately 1inch square bars. Then take them by the group, fire up a kiln to 600 F and open a small side door. Take one at a time and push it in as far as you dare and then pull out again in about 6 to 12 seconds. It will take the square body and melt, taper it to be a slight round with a hint of square but also slightly tapered from the holding end to the end in first ...
Gene - Sounds exciting Bruce.
bpfink - This makes the exact / ideal sprue for all my work as the metal will stay filled from the top down because of the crimp taper, and will nor swirl because of the slight squareness though the corners are now rounded
John D - Bruce is this the plastic rod you sent me?
bpfink - The rod I sent you John is just a 3/16 inch type PVC welding rod that works also but more for your smaller sized works. In that case I would dip it in wax first and then take a knife and remove one side length strip to stop any swirl (though on smaller pieces there probably wouldn't be any swirl anyhow?) That PVC welding rod is so strong you can either heat or cold bend to top into a hook for hanging your ceramic shell molds for drying.
John D - Where/what do you mean by the crimp taper?
bpfink - The taper is from the farthest end being in the kiln the longest and having shrunk the most. A Styrofoam sprue has one other plus... before the mold goes to the kiln upside down I put a hot wire in to start a melt and then pour in a cup of lacquer thinner so it removes the sprue before the burnout. That will help allow the wax to come out before it can expand and cause any flashing from interior wax expansion
rlow - By the way Keith, I'm also using Delrin for molds.
Gene - Wax injection I assume rlow
Keith - rlow, (Rick is it?) I may have that capability
rlow - Hey, Gene > Yes, and plastic, better detail.
rlow - Yes, Rick.
Keith - I've seen and actually cast numbers of pieces using the plastic injections from metal molds. I really like them.
rlow - Keith, what I'm doing is trying to get a CNC set up for the least money, so continue to use pantograph (manual) ....
rlow - Yes, Keith. You friend Kenneth in Brea is doing this also>
rlow - He told me about some plastic but I cant remember the name. I still have 50 lbs of kodak
Keith - Kenneth did tell me he is set up to do metal molds but there are a few others in the Cincinnati area who are doing it too. I should make the trip out to Ken's to document the process. One of these days it's only a bit more than a hundred miles each way.
John D - I do use a lot of wax sprues. Square ones, from 1/4 to 1" dia. and all but the 14s are hollow. The wax is a pink wax, good movablility yet strong when left for a while. A bit difficult to get to melt/join with the Victory brown as it's melt temp is low. I have not tried the foam as of yet Bruce, but it seems to have a lot of really great potentials.
enrique -here's another example of his modeling extremes:
bpfink - This is a companion piece meant to be facing the 1930's PORTRAIT PHOTOGRAPHER casting. It used PVC pipe, wood picture framing material, antique wedding lace, 1/8th inch curved plywood and felt dipped in wax to help set up the original model. In this case the model was removed intact by using a polyurethane rubber mold with fiberglas mother mold to make it an open faced relief mold for the next cast. Some of the smaller sections were wax for bronze casts to be later added to the larger piece.
John D - Bruce, interesting piece. What was the material? where the masters?
John D - AHHHH you answered my question before I got it posted.
bpfink - The model was not burned out but rather a polyurethane rubber mold peeled off it leaving the original intact for later modification or whatever.
John D - Was the mold one piece or a number of pieces?
bpfink - The mold is basically one piece about 8 ft. x 42 in. and about 14 inches deep. The extending bronze sections were originally modeled from styrofoam sheets that were cut and heated in a kiln to mold and form prior to the wax surfaces added for other modeling and alterations... then cast in bronze
John D - Was the bear real, stuffed or painted or what???
bpfink - Funny you should ask about that bear. Seems I have him in a lot of pictures walking around the house and looking in the open doorways.
bpfink - Borrowed and house sat him for about a week.
Gene - Don't tell us you were the model for Garp
rlow - Made a cool picture, Bruce!
John D - Bruce, for your investment, do you use regular plaster or potters #1 or what?
bpfink - I use #1 molding plaster and then add a retarder to control and extend the set time. It is usually mixed with about 50% of that common brick sand and 1 inch mesh chicken wire for added handling strength.
John D - What is the retarder. If you have the info. what would you use for an activator?
bpfink - salt will activate or accelerate but I never use it. So does warmer water vs. cold water; more active agitation or old mix from the last batch left in the next batch which will shorten the set time.
John D - What is the retarder?
bpfink - The retarder is powder bought separate along with the plaster but 20 to 30 years ago when I couldn't get it I took cow manure, put it in a tub, made a wet water slurry, strained it and then added a small amount of that... I prefer the newer stuff but got the old recipe from the Italian Master Plasters in the Chicago area.
Wray - John, it's available from your local contractor supply . I have some in powder form.
bpfink - I usually mix about 20 to 30 gallons of investment per pour and do this in quick succession till the molds are full. Some end up weighing 1000 to 2000 lb.. that way the bottom layers have set hard before I'm even 1/2 through pouring to the top. Same way they cast concrete grain silos and reactor towers using a single sliding mold as the investment slowly rises up.
John D - Bruce, I think I will buy the newer stuff. Interesting though what folks come up with. I would rather use the manure in the garden!!
bpfink - Some of those guys used the commercial retarder in the garden as well...???.
bpfink - Also use as hot a water as I can risk so the wax expands but doesn't alter it's shape. Try to keep any flashing to a minimum or to a nil
rlow - I've got to try this ceramic someday....
John D - Bruce, I saw a pre post you made to the list about the hot as possible water - expanding wax bit. Never thought about this before reading your post. Tons of food for thought.
rlow - Hey John, this guy has 35 years of 18 hours days- thought it all out!
bpfink - more like 42 years of mucking about. Ceramic shell in the right case is magnificent. For me the variables I test are easier to do with the plaster based mix.
John D - Rlow, if you are ever in the area, you and any other listener are more than welcome to give it a try here. Always got the wax tanks hot (about 80 gallons) and the slurry barrel mixed and the fluidized air bed full
bpfink - Actually I design and build custom homes a bit also so do less here than I'd like
rlow - I have a local friend who is doing sculpture, just gotta get time to waste....
Gene spliced - logged on. --- ( - Fri Apr 24 12:26am)
bpfink - Cast whole rooms sometimes but then it's usually in plaster or even fiberglas in case of a bathroom with the shower, sink and tub all one piece along with a 10 foot skylight shaft.
bpfink - Like to get sticky sometimes....
Gene spliced - so doo these peeble pay fer yer lungs sore.
John D - Rlow, it isn't wasted time. It is time spent differently than most of society considers "well spent" (usually translated to making the biggest bucks possible while being very unhappy with the whole situation.)
bpfink - My levis don't need a clothesline sometimes and the fire starter in the winter can be a hot flash in theee pants
Wray - Does the ceramic shell method work best for smaller castings and the plaster mix for large ones? Or is this purely a personal preference?
rlow - John- When it ceases to be fun, Ill pick another profession, ya know?
bpfink - I did over 100 ceramic shell molds in the mid 60's and even helped develop it but just prefer the limits I push the molds and prefer the disposal of the residue though the quantity is greater. Good for the land as sand and limestone to counter the acid rain...?
John D - I think that investment works for either (we use it for small things i.e. rings) but the shell works for medium to larger items but they cannot so large that you are unable to handle the piece to dip and wand it (and the slurry and sand does get heavy!!).
bpfink - I tend to like to do the investing all at one time and then spend a long burnout time doing something else with a heated studio (5 to 7 day burnout)
John D - Well I really liked this chat. I am sure there are a ton more questions but it is a good start.
bpfink - Thanks for being here John, it's a big broad subject all right. When we have this edited we could add any other good wax addresses to the end of this so if you all got any let me have them.
John D - As to the disposal of spent investment or shell materials, both are pretty easy on the environment once fired.
John D - Bruce and others, thank you for your time and inputs. It really has been a grand time. I hope to be here often!
bpfink - Your residue John could be the envy find of Archeologists in years to come, mine will be mush by this spring.
John D - Tis true the shell does hold together, but what is there is not a toxic problem.
bpfink - I'll say nite now guys... Thanks for all and slowly I do get the hang of it.
Wray - Yeah it's time to say goodnight Thanks all!
Gene spliced - JD where in the world are you located..
John D - I am in Northern California. Look on a road map and find Ukiah (county seat of Mendocino) and draw a line due west. Philo is about 1/2 way to the coast. Timber (redwood and fir), sheep and apples (both disappearing), champagne cellars and vineyards
Gene spliced - john, nice and nice chat gotta try and sleep fer a bit, bye all

#specific addresses The following product addresses and the WAX SHAREWARE comments are being added after the chat. They are only meant as being some that work and are used by the folks here tonite. Others in your immediate areas might be better for you to cut down shipping or product costs. Good Luck.

Most of these waxes are sold in ten lb. slabs in a minimum of 50 lb. boxes. Check sources for current prices. Most dealers also sell many other types and styles of wax but the following were recommended for ones mentioned in tonite's CHAT
Kindt- Collins Co. @ 216-252-4122. They make sheet wax for the industry.

MICROCRYSTALINE Premier Wax Co. Inc. 3327 Hidden Valley Drive
Little Rock, AK USA 72212

ROSIN M chunks REED WAX Polishing and Buffing Compounds
ROGER A. REED, INC. 167 Pleasant St. Box 508
Reading, MA USA 01867-0690

(2 parts Rosin M mixed with 1 part of Yellow Ceresine Wax to make a very hard / brittle/ stable wax with a high melting but very low cooling point for interior slush casting large forms)
YELLOW CERESINE WAX #20 Frank B Ross Co. Inc. 22 Halladay St.
Jersey City, NJ USA 07304

RePrint from ArtMetal Forum
Microcrystaline wax happens to be my all time favorite main modeling START.
Since it in itself is not thought of as a final media it nearly always has to be
transposed into something else. The lost wax process usually offers the easiest
method if the subject has any degree of undercuts, surface detailing or intricacies.
Prior to this step though I would like to present one of the systems I use frequently
to make a wax mold off of a wax to cast multiples of the original wax form.
Polyurethane molds are also used on some forms in order to be able to slush
cast wax with a controlled thickness. Costs, time and usage is valid at times but can
be prohibitive for many smaller general duplications. These initial forms may
incorporate styrofoam using woodworking and heating tools as well as pneumatic
extruded wax die forming with variable shape configurations but this is another

Hand held sizes often are quickest, easiest and cheapest to duplicate or even
slush cast when the mold itself is also wax. You make a wax mold BY
1 Make the first wax positive cold (ice water or a freezer
works fast).
2 Surface with a silicone type parting spray. (Liquid soap
works too but has other characteristics and must dry on and be later washed off
with water, then the whole thoroughly evaporated dry before re-melting for further
3 Dip in a minimally hot liquid wax / ice cold water dip / hot wax / cold water /
etc. and build the new negative mold surface up like a candle until 1/4 to 1/2 inch
thick depending on the size of the positive form.
4 If this form needs any additional mother mold type support for later handling
add it to this step using sticks, styrofoam , cloth, or built up wax buttered on and
redip to lock it all together.
5 As it solidifies but while still able to be cut with a razor knife make parting cuts
where the mold should separate. Cut with a jagged pumpkin top curve so the parts
will interlock again later. Sometimes in addition to this I put one or two strips of hot
waxed cloth over the part to make a hinge out of it for later closing.
6 Open the mold and remove the original while it is hopefully still colder than the
negative mold body.
7 Next reverse the process by spraying with the silicone and closing the mold.
Butter wax the seams and put it in the freezer.
8 When cold... bring out and pour in minimally hot wax to make the first positive copy. This
temperature is important. You want it to quick coat the surface without any rings but also to not be
so hot as to be able to melt into either the mold surface or the parting agent. Let both cool and
then put the mold in warm water to reverse it's temperature and make it the warmer half.
Do it right and you can make numbers of duplicates within less time than just
making one plaster or polyurethane mold not including still having to wait an hour or
day or so for it to set or cure.
Do it wrong and you just wasted an hour or two plus the original positive.
All wax used is set aside and later washed if soap was used or melted in a
separate pot if silicone was used. Once re cooled the silicone will have floated to the
top of the block and can be wiped off with a paper towel.
This is not for faint hearts so if you give this a shot first try it on a relief shape
you have less tie to. Relief's are a snap. Then try it on a plastic toy for the first
positive and see if making a mold and then a wax positive works for you. It will also
give insight to all the minor points passed over here in regards to pouring into a
closed wax form with one sprue and one or more air vents (soda straw vents work
Honest... I do this all the time and it makes for very efficient, cost effective positives with near but not quite finger print detail. If you use different colored or heat setting waxes (such as 2 parts rosin to 1 part wax making it a lower melting point and hard as a wood block body) it can also work easier but might start to contaminate the wax types if re-melted later... I just use the same Victory grade Microcrystaline wax for all stages.
Good luck and this is really not a joke but never the less don't call me.
You don't have to know where you're going to enjoy the road you're on.
Deepak Chopra (sometimes.... bpf)

Estimado colega:
Yo tambien soy escultor y fundidor en España, y me ha resultado muy interesante las
técnicas que describes sobre el moldeo con cera. Veo que has profundizado mucho en ellas,y
ienes interés por compartir conocimientos.
Pues bien, yo hace ya algunos años que usé ese tipo de moldes con muy buenos
resultados, aunque desde hace mucho tiempo que no he vuelto a usarlos. Te puedo constatar que
realizé moldes de cera de figuras de bulto redondo de hasta 1,5 metros de altura, a base de
reforzar la cera con FIBRA DE VIDRIO y varillas de hierro.
Te asaguro que se trabaja igual a como se trabajaría el poliester reforzado con fibra de
vidrio. La cera del molde recuperable despues de hacer varias reproducciones. Si
experimentas con lo que te cuento verás que moldes semirigidos más rápidos se pueden hacer.
Pedro Hurtado

( Translation courtesy of Keith Farley)
Esteemed colleague,
I also am a sculptor and caster in Spain and I have found the techniques regarding
molds and waxes very interesting. I see that you have gone into these areas deeply
and you are interested in sharing your knowledge.
Well then, for several years I used that type of mold with very good results,
although it's been a while since I did use them. I can (tell ?) you I that I was able to
realize wax molds of figures of round mass up to about five feet in height, providing
the wax a foundation of glass fiber and small steel rods.
I assure you that this works as well as the application of glass reinforced polyester.
The wax from the mold is recoverable after completing the various reproductions. If
you experiment with what I am suggesting you will see that semi rigid molds can be
made very rapidly.
Pedro Hurtado Spain

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investment casring

realy i have a question a bout casting. why we pour the melt to mould? if now that the investment casting have high resistance to heat (alomina mould). i have an idea about new process that donot need vaccum to casting. my email is .