Bronzework mini-blog

[fritchie]

I had expected to post a miniblog on bronze chasing and patining, following a conversation mainly between rod (sculptor) and me, but I’ve had technical difficulties, as they say, and it will be a bit sporadic. Essentially, my digital camera is being flaky and had to be returned to the manufacturer. Fortunately, it’s still in warranty, and shouldn’t cost a great deal (cost unknown to date). Here’s the first installment photo, taken today.

I gave two recently finished clay torso’s to my foundry a couple of weeks ago, to make molds and waxes for pouring as bronzes. I’ve decided on an initial edition of two pairs, and here is the first pair, poured just yesterday (May 9). They had given me the four rough waxes and I had returned two finished waxes last week for yesterday’s bronze pour.

In this picture, the main assistant has broken my two pieces out of the molds and set them against other molds to photograph. For scale, the two torso’s are each about fifteen inches high, without casting sprues and so on. The unbroken molds give an idea of the process. This is investment casting, not ceramic-shell. The bronze disks attached at the base of each figure actually are pouring cups, into which the molten bronze was poured, with the figures cast upside-down. Rectangular feed channels or sprues between the cup and figure are visible in the female, but hidden by unbroken waste mold material (ludo) in the male.

Exit or vent sprues are visible in both figures, running from the top of the neck outward and downward. (Remember, the figures were cast upside down, so the molten bronze ran into the cup, through the feed sprues into and through each figure, and then out the neck into the vent sprues. These vent sprues are “blind” in that they do not rise to the same level as the feed cups. This is a recent innovation in his procedure, which he probably used because these figures are relatively small. Investment molds, unlike ceramic shell molds, are a bit porous, so air within the blind sprues, but not the incoming bronze, was able to escape through the mold material itself.

I ran into camera problems shortly after taking these photos, so I may have to wait until the second set of torsos is cast in order to continue with photos. From the state in this picture, the casts were pressure washed with a water jet, both inside and out, to remove waste mold material or ludo, and the assistant cut off the various sprues.

At that state I took charge. I will extract the small amount of ludo remaining within the casts, and will chisel or grind off the sprue stumps and small bits of “flashing”: metal that escaped into tiny cracks in the mold. Contemporaneously with chasing, the finishing process will begin. As I described in the earlier thread, I will acid-treat the cast to remove most but not all firescale, and will wash away the acid with overnight water and ammonia baths. When chasing is complete, chased sections will be resurfaced with the ammonia - diatomaceous earth paste. Then, patining and waxing will take place.

[sculptor]

Thank you Professor Fritchie:
I think I'm gonna treasure this journey.
I wish your camera a speedy recovery

¿?

hollow cast? process? grog used for interior part of mold-----from pix, I'm guessing that the nails are to hold the inside and outside molds in position as the wax is "lost"........true?

UH OH_________"overnight water" ¿?

Fire scale-------¿ the natural discoloration/patination of the bronze from the fire and reaction to the mold?

(stray thought) a ceramicist i knew used proximity to other glazes in the kiln to shade/tone the color. (extrapolating from known data) could the bronze be somewhat patinated via the introduction of other metal salts (contaminants) into the surface of the investment mold?----do you see that around the nails?

rod

[fritchie]

Thanks for picking up on the nails, Rod. I realized later that I hadn’t mentioned them. Yes, they are positioned strategically on high points around the piece, in areas easy to chase and weld, and the purpose is to anchor the interior section of the mold in a hollow cast. Ideally, waxes for this size piece are something like 1/8 to 3/16 inch thick, and that’s what we have here. The nails usually are corroded a bit in the casting, but most often can be removed with a bit of knocking or twisting. Sometimes they must be drilled out. It is essential, of course to remove the steel before welding the holes.

I left the pieces in my studio overnight because I had other business yesterday, but I pulled out all nails this morning and began soaking the casts in a tub of water to soften the remaining mold material. This afternoon, I washed the female completely clear of mold residue, and was able to pick away at a relatively large residue within the male. A long metal rod, sharpened a bit on one end, and possibly bent to get around corners, helps with this. Both pieces are back in water for an overnight soak.

On your other questions, yes, firescale is the coating that develops during the casting process. Typically, I have found it to be black, but in recent years, this founder has sprayed the waxes with something that keeps them cleaner, a fluorosilicone, I believe. It has little or no detectable effect on the surface, and the bronze, as in this pair, often comes out a clean, reddish bronze color. The alloy is silicon bronze, by the way, direct from the producer, and welds are by tig, with rods of the identical metal. Literally, there is no color change at the welds.

As I look back at the original picture, I see some of the “cleaned” bronze color on the bottom of the male’s right leg. The extreme bottom of his left leg is blackish, now that the pieces have been washed. Overall, both pieces mostly are a natural, clean bronze color. The whitish appearance in this first photo basically comes from residual mold dust.

[jwebb]

Here's a bit on foundry jargon, having worked in it daily for 30 years. "Sprue" is specifically the main channel, attached to the pour cup or "tundish", through which the metal is poured. The channels which branch off the sprue and feed various parts of the casting are "gates", and those which branch off and upward from the casting to carry off air or gas pushed out by the metal are "vents" or "risers". In large Sand foundries, where molds are often built into the earth floor, metal is basically poured until it's visible coming up out of the risers. Where I work we have a whole dictionary of foundry lexicon, including explanations and photos of typical casting defects: Cold shots, cold shuts, inclusions, many differentl varieties of "shrink", etc. In fact, it's called the "Defect Dictionary", or, among friends, the "Defective Dictionary".

[ExNihiloStudio]

This is a very cool blog. I'm looking forward to the next installment.

[sculptor]

... nails, ... and the purpose is to anchor the interior section of the mold in a hollow cast. ........

follow-on question
¿ is the interior section of the mold left in place? And/or, does it soften and pour out with the water soak?

and: (intended) to better illustrate the ongoing..seminar...
here is a scanned image from book-Sculpture Casting 1972 by Kowal and Meilach--(which has replaced "ancient chinese mythology" for my nightly reading)
the caption reads--".......illustrates ...how the sprue system is attached before the wax is completely invested..."

I hope this is helpful

rod

[fritchie]

Here's a bit on foundry jargon, having worked in it daily for 30 years. "Sprue" is specifically the main channel, attached to the pour cup or "tundish", through which the metal is poured. The channels which branch off the sprue and feed various parts of the casting are "gates", and those which branch off and upward from the casting to carry off air or gas pushed out by the metal are "vents" or "risers".

Thanks, jwebb. I’ve heard the terms gates and risers here also, but among friends, things are looser. I should have been more careful, and thanks for clarifying the terminology.

[fritchie]

follow-on question
¿ is the interior section of the mold left in place? And/or, does it soften and pour out with the water soak?

and: (intended) to better illustrate the ongoing..seminar...
here is a scanned image from book ... etc. ...
rod

No, Rod, the interior mold should be completely removed if possible. If left in place, it can attract and retain moisture and/or caustic agents, causing long-term corrosion. In fact, that is today’s installment.

I had a bit of time at the end of the day to visit the studio. After filling and emptying the female form a couple of times, completely within the “tub” - actually a 30 gallon plastic garbage can with a rubber kitchen drain board at the bottom for protection, she was completely free of interior mold material.

I also got the male about 95 - 98 % free of interior mold, by punching at the previously hard or hidden areas with a straight rod or bent wire, as I described earlier. Both are continuing to soak, and I hope to have both completely clean on the inside by tomorrow. Of course, grinding and other finishing can overlap with these soaks, and I plan to start that tomorrow as well.

[And, ExNihilo, jwebb or others; please chip in here with other perspectives anytime you like. The more variations, the better!]

[jwebb]

I hasten to add that it doesn't matter whether you call them "sprues" or "gates" or "chopped liver". You are right on with all you've said, Fritchie, and your photos are great. I could expand about some things that are done differently in industrial foundries (for example, caustic baths and robotic water-blasters are typically used to dissolve and knock off the mold material), but your example is much more typical of what a sculptor will encounter having bronzes cast. And, though as mentioned before one can pay to have all this labor done by the foundry, and have a "finished" piece delivered to the door; and most foundries would prefer we do that; what you're describing is the hands-on detail work that imparts individual character to the piece, and it's also the "fun" stuff.

[fritchie]

I hasten to add that it doesn't matter whether you call them "sprues" or "gates" or "chopped liver". You are right on with all you've said, Fritchie, and your photos are great. I could expand about some things that are done differently in industrial foundries (for example, caustic baths and robotic water-blasters are typically used to dissolve and knock off the mold material), but your example is much more typical ...

Thanks for giving this thread a broader perspective, jwebb. As I have said, I don’t consider this a personal “blog”; just a journey down the road, and all comments, insights, alternate views, or whatever, are welcome!

On the work-in-progress, today was another of mainly extracurricular activity, but I did get to the studio this morning and got the last bit of mold out of the male figure. Both are drying so I can begin the chiseling and grinding tomorrow. I’ve cleaned the tub and put in fresh water for regular overnight soaking of the figures. I like to leave pieces in water overnight, to start the “2000 year” soak described by Sculptor.

Seriously, I find that bronzes “age” or patine naturally faster in water than in air. I like this because the water helps restore worked areas to a proper state for a later patina.

[fritchie]

As I said earlier, I don’t expect this to be a real blog with daily posts, but I did begin chasing today, by starting to grind away the sprue stubs on the bottom of the female so she will stand straight for further work.

Here are vital stats on the two pieces, now that they are clean. Some sprue material remains, but this should not affect weight significantly. Numbers in order are weight in pounds, followed by height, width and depth in inches. Male: 22 pounds, 14 1/4, 9 1/2, 5 1/2, and female: 15 pounds, 13 1/2, 6 1/2, 4 1/4. Normally, I round dimensions to the nearest inch for recording.

One thing I noticed again today and thought I should mention. The apparent color of these bronzes varies quite bit with light source, at least indoors. I’ve never looked closely outdoors at this stage, and that’s something I should do. In fluorescent light, these two figures look about 80% covered with a black firescale, but it clearly is thin, because the bronze color shows through. In light from regular incandescent lamps or photofloods, most of the black color disappears, and they look a cleaner, deep bronze color.

I’ve always seen this in my pieces as I chase and later patine them. What I do in patining is use a halogen lamp, which is broad-spectrum, close to sunlight, plus three 150 watt spots, and the overhead fluorescents. This brings out the bronze color and should be close to illumination the figures typically will receive in both a gallery and later with a purchaser.

[fritchie]

I finally got back my digital camera. They say they found nothing wrong, so the local shop says maybe an intermittent fault. We’ll have to see, but for now it’s working, and here is a picture of the female in my latest pair.

Unfortunately, the legs were joined by thick bits of flashing which will be awkward to remove, so I’m getting the male ready first, to have something for the gallery’s summer show. This picture mainly is to show the welds before any grinding. Five nail holes can be seen, filled with plugs which need to be ground flat and textured so the surface is similar to the surrounding area. There’s also a small repair under the right arm and one at the base, on the leg.

The piece is lying on the edge of my main work table - a sheet of about 3/4 inch plywood supported on loose concrete blocks. I set this up ad hoc when I started, and it’s worked fine, so it’s still going. Two bags of heavy blue, plastic-covered fabric half-filled with sand support the figure. These are an inspiration of the founder’s, which he had made for his own use. He sold me two, and they are perfect for use either under or over these irregular casts. They anchor things quite firmly for chiseling or grinding.

A large depression formed on the backbone where part of the mold shifted. Shifts like this, along a broad cavity in the middle of the back happen with uncommon frequency and may be related to localization of expansion/contraction forces as the mold is heated or filled. In any case, the foundry is good about welding these areas with minimal metal and they’re not difficult to chase.

[fritchie]

The male figure here is almost fully chased, except for a welded patch about 3/4 inches across on the lower left leg, in a spot hard to reach. This weld is marked with an arrow.

My two main tools also are shown - a 4 inch angle grinder and a die grinder with a flame or spiral tip. I do use other grinding tools, but these do nearly all the work on simple shapes like these.

Two chased but not textured nail welds also can be seen in the middle left back and right buttock. These also are marked with arrows.

[fritchie]

Here’s the male torso essentially ready for the final stages of texturing the worked areas, and then patining. The dark areas on both legs are residual fire scale that was not removed by the dilute acid bath. Sometimes mixing in the tall trash container I use for this is not complete, and scale on the extreme bottom is not removed.

(The ideal acid concentration is so dilute fire scale isn’t removed by acid alone, but is loosened enough to be removed with a bristle brush. That weak solution doesn’t leave much room for error.) After taking this picture, I cleaned the dark areas with Q-Tips - small cotton swabs twisted on the ends of thin wooden pins - dipped into more concentrated acid. Dabbing with acid is followed by dabbing with dry paper toweling, and it does the job well in a localized area, leaving an irregular edge and color.

[obseq]

Fritchie,

This blog is a great addition.

Your pieces look great--I always figured they were rather large but I think it is because they have a very imposing quality, which I admire about them.

Do you leave the mold-making to your foundry or do it yourself?

With my own work, I've been told to do the mold-making to minimize my final costs but have no idea where to begin.

If anyone knows of a good resource in Los Angeles, I would appreciate it. I contacted a foundry out here and was a bit weary of proceeding with their estimated costs considering they never saw any of my pieces.

[sculptor]

hi fritchie

Thanks for picking up the bronze finishing and patination process again.
( a nod to the techno gods as/re the camera--(fingers crossed))

cupric nitrate ? the cupric part relates to copper? and the nitrate part is a salt of nitric acid?--what exactly is this?----and--this yields a coppery or reddish tone?...and I'm guessing that when adding these salts/acids(?) that they bond to create a surface alloy modified from the original silicon bronze



rod (http://home.mindspring.com/imagelib/sitebuilder/misc/show_image.html?linkedwidth=actual&linkpath=http://home.mindspring.com/~mandali/sitebuildercontent/sitebuilderpictures/IsisOsiris2pixSmudged.JPG&target=tlx_new)

[fritchie]

///////
Fritchie,

Your pieces look great--I always figured they were rather large but I think it is because they have a very imposing quality, which I admire about them.

Do you leave the mold-making to your foundry or do it yourself?

With my own work, I've been told to do the mold-making to minimize my final costs but have no idea where to begin.
.......

Obseq - Mostly, I have made my own molds, of polymer rubber, but I left the molds and also the wax casts in these cases to the foundry, because of limited personal time. I did go over the waxes myself, erasing joint marks and other small flaws such as tiny surface bubbles. This runs the cost up, of course, but life always is a trading game.

On moldmaking, you probably can find books on technique in a college or good city library, but you really just have to try. Find an expert for advice if this is possible. I learned with sulfide-rubber molds in a college course about 35 years ago, and the current polymer rubbers are a breeze in comparison. Good luck with this!

(And, on size - Thanks for the comments. These happen to be some of the smallest pieces I have done. Others typically are as much as 2/3 life size, or about 4 feet for a standing figure. Here, I'm working to generate a variety of body forms, so I want to keep things relatively quick, but large enough to be effective.)

[fritchie]

hi fritchie
Thanks for picking up the bronze finishing and patination process again.
( a nod to the techno gods as/re the camera--(fingers crossed))

cupric nitrate ? the cupric part relates to copper? and the nitrate part is a salt of nitric acid?--what exactly is this?----and--this yields a coppery or reddish tone?...and I'm guessing that when adding these salts/acids(?) that they bond to create a surface alloy modified from the original silicon bronze


Sculptor, rod - Cupric nitrate has formula Cu(NO3)2, and you’re right on the first two suppositions. The cupric part refers to copper with a +2 charge, and nitrate is part of nitric acid. Nitric acid has formula HNO3.

However, when cupric nitrate is brushed or sprayed on the bronze surface, it undergoes some fairly complex changes that I don’t fully understand myself. Not that the chemistry is difficult, it’s just that several things are happening at the same time, and the result is a mixture.

No alloy is formed. (An alloy generally is considered a mixture of neutral atoms, and everything happening here involves + or - ions.) Instead, the materials deposited on the bronze surface all are salts, with + and - charges involved.

The cupric nitrate picks up carbon dioxide from the air and converts to cupric carbonate or a mixed cupric nitrate - carbonate, possibly with a little cupric hydroxide or cupric oxide added. (Hydroxide is OH-, and oxide is pure oxygen with a charge of 2-.) You see the complication when all these things are happening at once. Adding to the theoretical complications is the fact that almost all of these compounds have water (pure H20) chemically bound to them.

Only the result is important from an art standpoint, and the result is a thin, essentially opaque coating of pale blue, blue-green or grayish white. These colors can mix from place to place.

Ferric nitrate, which is Fe(NO3)3, is similar, but with iron instead of copper. Ferric nitrate, however, produces reddish salts that are more transparent that the copper salts.

When I say opaque, bear in mind that the salt film is very thin, so the bronze still can shine through it. The effect is a rich mix of the original bronze color, various blues, greens, grayish-whites, and reddish tones.

[sculptor]

....
No alloy is formed. (An alloy generally is considered a mixture of neutral atoms, and everything happening here involves + or - ions.) Instead, the materials deposited on the bronze surface all are salts, with + and - charges involved. ...
The effect is a rich mix of the original bronze color, various blues, greens, grayish-whites, and reddish tones.

a thin layer deposited-------would you get the same colors if the "patina" were cured on a ceramic plate? or, Is there a borrowing of Cu from the bronze to create the thin layer?

rod (http://www.sculpture.net/community/attachment.php?attachmentid=609)

[fritchie]

a thin layer deposited-------would you get the same colors if the "patina" were cured on a ceramic plate? or, Is there a borrowing of Cu from the bronze to create the thin layer?

Interesting question, and a little difficult to answer. Remember, we’re talking about applying the patina material(s) and heating to dryness, and then repeating the process up to many times. If you let cupric nitrate dry on a ceramic plate, it probably would remain cupric nitrate. Actually, the normal form of cupric nitrate has water, H2O, chemically bound, as I said in the patina description. I think the common form is a pentahydrate, with five molecules of water to each copper ion, Cu(2+). This is quite a stable compound, and it won’t change if left to itself. (Actually, the solid sucks water from the atmosphere into itself, and it eventually will dissolve in this attracted water, if the relative humidify is something like 30% or more.)

If cupric nitrate is repeatedly heated to dryness and then redissolved on a ceramic plate in the air, it eventually might attract enough CO2 from the air to form the carbonate I described, or it might not. I just don’t know.

On the other hand, with neutral copper present as part of the bronze alloy, the Cu(0) and the Cu(2+) can react to form the intermediate ion Cu(+), and this one offers many more possibilities for making salts. The chemistry can be much more complicated than I indicated above.

[fritchie]

Yesterday afternoon I went through the procedure of mixing and applying the paste of ammonia and diatomaceous earth for retexturing the chased areas of the male figure, and here is the result. The figure sat overnight, and the masking tape has been peeled away. As a reminder, the purpose is to blend texture so working is less noticeable, and regain a matte surface for greater depth of color in the patina.

The paste is a barely damp mix of powdery diatomaceous earth with ordinary hardware store (concentrated) ammonia. I apply the paste with a flexible metal spatula, spread it to cover a specific shiny spot, and then add the tape so drying is delayed over a couple of hours.

You’ll see that the centers of these retextured areas often are black, with the surrounding area blue from the ammonia. When I first developed this method of retexturing, I could get spots with no blue, by keeping the paste almost dry. That way, no dabbing later with acid was needed. Things actually go faster now if I don’t worry too much about getting the paste just right, and just dab away the blue.

(I couldn’t get pictures yesterday, so I added a few more patches today where minor shiny spots remained, principally for photos. These actually did their job while I was getting the camera ready and taking pictures.)

The next step is to dab away these black-and-blue spots with Q-Tips and a fairly concentrated muriatic acid (HCl), just as I said I did with the remaining fire scale near the bottoms of both figures.

[fritchie]

The male now has had all the blue and black patches from the retexturing dabbed away with muriatic acid, and it has soaked for about 3 - 4 hours in a tank of water. Immediately after acid - dabbing, all the retouched spots were very light tan in color, somewhat like the large areas now present on the figure’s right abdomen and leg, but generally even lighter.

Actually, I’m puzzled by these remaining light areas. They’re not regions specifically retouched with ammonia and acid. Patining bronze clearly is an art and not a full science. These spots may be gone by tomorrow. The figure is soaking overnight in pure tap water, for more natural darkening.

I’m convinced, without proof one way or the other, that this brownish patina which develops in water is cupric oxide, CuO, and that it is produced by oxygen naturally dissolved in the water. Both cupric oxide and cupric sulfide (still to be discussed) are black unless present in very thin layers. In thin layers, both are shades of brown, with the sulfide much darker.

Cupric sulfide will be one of the main colors developed on the surface in the final patining. It is produced by brushing the surface with “liver of sulfur” or potassium sulfide, with ideal formula K2S. I say ideal because this material almost never is pure in art applications, but the available material essentially acts the same as K2S.

I forgot to mention in an earlier post - the neat (I think) violet-black background is simply my white studio wall, too far back for the overhead illumination to reach it.

[fritchie]

I patined the male today, and will put up some “process” shots as I have time, but here are front and back after waxing, but before buffing. They always are waxed warm so the wax will “penetrate into the pores” in local terminology. The wax gives a wet or liquid appearance, and certainly enhances color.

I used real beeswax for this piece, the first I have been able to find at a semi-reasonable price in several years. On the advice of a visiting professional patinist at my sculpture school a dozen or so years ago, I bought an artificial beeswax then, and it was great until it ran out. I’ve searched on and off for a substitute since then, and some were OK, but I hope this is closer to the earlier wax in its effect. That one was essentially pure white in the container, and this new wax is almost white - a fairly light yellow in color. The waxes I’ve used since the first ran out were softer and wouldn’t take as high a sheen.

I always leave the pieces to cool overnight, and I’ll post final images tomorrow.

[ExNihiloStudio]

fritchie -

Why did your founder use iron instead of bronze of identical allow to pin the cores? Is there any iron residue left behind to affect the patina?

[fritchie]

fritchie -

Why did your founder use iron instead of bronze of identical allow to pin the cores? Is there any iron residue left behind to affect the patina?

Mark - I think he’s concerned about melting the bronze pins. He uses ordinary hardware-store nails, usually common (with large heads), about 8-penny size. Often they pull out cleanly. If any residue is present (from oxidation in the casting), it is easily drilled out.

Every so often, if the wax is thick, I haven’t been able to drill completely through, and the weld still seems OK, as it is only about 1/8 to 3/16 inch think. In these cases, you can see the residual nail from inside, usually protruding from an indentation of bronze, the shape of the wax as he pushed the nail through. Those could cause trouble over time, but I doubt it. Iron will corrode before bronze, and I expect it will simple flake away, over a couple of hundred years, (if the piece is around that long! - I hope!)

[fritchie]

Here basically is what I have on the technical side of patining. --

Here’s my patina setup, solutions and brushes. The sculpture is supported on a rotating stand, on a cinderblock for application of heat, as in other pictures. This picture shows the three solutions, in two concentrations each, with two brushes for each type of solution, plus pure water and a large brush for the water.

The water is chemically pure, or distilled. This might not be necessary, but it is cheap in drugstores or grocery stores, and the pure water leaves no question about possibly contaminating the solutions. The three patina materials, from left, are liver of sulfur or potassium sulfide (yellow to orange-brown), ferric nitrate (reddish orange), and cupric nitrate (blue).

I realized as soon as I started using the sulfide and cupric solutions, that the dilute solutions still were too concentrated, so they should be much lighter in color than these. I diluted the sulfide about ten to one, and the cupric about 3 to one, before continuing.

The final images, posted earlier after application of wax but without buffing, and (to be) posted today with buffing, show the effects of the too-strong sulfide - dark brown streaks. I’ll say more in the comments on the final images, but this also happened with my last pair of torso’s, and I decided to accept them. I went ahead with the streaks on this pair also (only the male so far).

As to application - Sulfide always is applied first, as a base, and is heated to dryness, with water-brushing for uniformity. The ferric and cupric solutions can be applied over each other wet, but neither can be mixed wet with sulfide, or both materials will be “killed”. From this start, it’s do as you will, drying each application with the propane torch. The streaks on this piece came from a too-concentrated “weak” sulfide.

The same thing happened on my last pair, many months ago, and I decided to keep it rather than start over. I think the irregularity lends energy to the figures. Strange how serendipity enters life.

PS - Only the base of the propane torch appears in this photo, next to the box of matches. I usually heat the sculpture in front of a gas-fired space heater before starting, to conserve propane.

[fritchie]

Finally, two views of the finished, patined, waxed and buffed male - “Male Torso 3".

As I said in the last post, the dark streaks, basically from sulfide, appeared accidentally on my last pair of torso’s and I decided to keep them then because I think they add a sense of energy without being too distracting. The same accident happened here, as it’s been quite while since I finished the last pair, and I kept them for the same reason, plus consistency. Berserk maybe - who is to say?

[obseq]

Finally, two views of the finished, patined, waxed and buffed male - “Male Torso 3".

As I said in the last post, the dark streaks, basically from sulfide, appeared accidentally on my last pair of torso’s and I decided to keep them then because I think they add a sense of energy without being too distracting. The same accident happened here, as it’s been quite while since I finished the last pair, and I kept them for the same reason, plus consistency. Berserk maybe - who is to say?


Fritchie,

Thanks for the pics and especially the previous post on patining--I've actually copied and saved the pointers for future reference.

You mention some results ultimately becoming 'distracting.' What sort of problems might arise in a patina? It is clear that you are intimately familiar with the process off applying a patina but what sort of variances could lend itself to a distracting final product even if the practitioner(you, I suppose?! ;) ) and process are fairly consistent?

[fritchie]

Jason, obseq - What you have going on here are two things simultaneously - shape and color, which are at variance. The dark streaks or brush daubs are most visible in the final piece on the right shoulder, flank, hip and leg. They strike me as more prominent in real life than in these pictures, and I think they also are more visible in the earlier, waxed but unpolished images.

You can think of these marks as tattoos, but unrelated to body position, and with nonspecific shape. In my more optimistic moments, I think of these pieces as multimedia sculptures - the elemental shapes, and the color variations syncopate with each other, much as contemporary radio or TV programs will interrupt conversation with interlude music. All this was accidental, of course, and the rationale is after the fact.

All the same, if someone is expecting a flat, uniform patina, this isn’t it. I never have liked very uniform patinas, and always have gone out of my way to retain a part of the original blackish firescale when possible, or to regenerate color variations naturally by regular overnight soaks in water. This piece, the upcoming female, and the last pair just go much further than before, and the marks clearly are streaks rather than the irregular blobs of residual firescale.

As far as control, I could have removed these streaks selectively with the concentrated ferric solution, which acts as a weak acid when it is hot. In fact, I did just that - I softened some of the early, strong brushmarks by partly erasing them with concentrated ferric, and I then reapplied more dilute sulfide to blend back.

Practice definitely helps with this. An understanding of the basic chemistry can help also, but is not necessary.

The female is coming along (with chasing). Hopefully, she will provide more illustration, but I don’t expect to go into the same detail.

[fritchie]

I finished chasing my female torso yesterday, and got her patined, photographed and delivered to the gallery today, for Saturday’s White Linen Nights summer-ending area art opening.

I’ll have to put up the before and after color shots later, but here is an overall view of a portion of my messy studio, ready for the patining. This shot wasn’t particularly planned, except for a better view than before of the work area.

The figure, as before, sits on a concrete block, atop a rotating stand. The work area in front actually is my main modeling stand, a reinforced platform something like 3 x 4 feet in size. It has large castors for rolling, but generally sits atop four sets of concrete blocks. It was constructed as a base and support for a life-sized clay in a life-modeling class at my art school many years ago.

In the back, leaning against the wall is a larger modeling stand I made for a variety of poses - seated, reclining, and so on. It also has castors, which currently are useless because of much taller legs I added to raise it for a reclining model.

In the rear are wall-attached shelves for storage of molds and other materials. Over time, some molds have hit the floor, as can be seen.

[fritchie]

Here are front and rear views of the female, ready for patining. The surface is uniformly quite matte, despite the whitish reflections. The more orange to yellow areas are spots treated with the ammonia - diatomaceous paste and then cleaned with muriatic (hydrochloric) acid. The blacker areas are untreated from the original casting.

The whole piece shows the effects of many nights immersed in water between bouts of grinding, rasping and filing. Worked areas typically are finished (before the paste treatment) by a circular rubbing with small pieces of pumice, about 1 - 2 inches in diameter. I began using pumice probably 6 - 8 years ago, after reflecting on how the Greeks might have finished their pieces. It is a good substitute for mechanical flapper wheels (sandpaper files), and I find the pumice more flexible in use. For larger pieces than mine, many people might find this handworking excessive.

[fritchie]

I was a bit rushed to get this piece to the gallery for today’s citywide opening, so I didn’t take time to set up the light diffusers, and the lighting is on the sharp side. (Always a mistake, but sometimes necessary! She was dropped off at the gallery late Tuesday, but it took me until today to get the pictures cleaned up.)

Anyway, here she is, Female Torso 3, patined and fully buffed for the public. I gave her some of the same dark streaks as on the male (Male Torso 3), but more subtle.

[RRussin]

Can anyone here recommend a good foundry in the Los Angeles or Riverside CA area? I've tried contacting the Pour House downtown, but after ten unreturned phone calls I've given up on that one.

Thanks!

Robin Russin

robin.russin@ucr.edu