Glass and Gold and Gilding

I've signed up for a couple of mosaic classes in April and May. It reminded me I wanted to try my hand at making Byzantine-style tesserae, and then a friend's Facebook post kicked me into high gear. She had much better success than I did and shared some of her wisdom. My test piece:

Two pieces of clear fusible (Bullseye CoE 90 Tekta clear) with one layer of gold foil sandwiched

Rhode Kephalaina let me know in her sample chips, marked 1 and 2, thats the sheets of foil. So, chip '1' has four layers approximately, and '2' with 8. My samples above are 4" square, not 1", and had one layer. It's not exactly ugly! It's just not the beautiful gold glass expected. The nicer parts of mine are where the foil doubled on itself (see Lessons learned, below...) I know now to fix it, though, thanks to a conversation with Rhode.

Ive also fallen for verre églomisé. Predating Rome, pretty much, this art (gilding glass and painting the back black) was practiced through the Roman period into modernity. It gets its name from an art collector 200 years named Glomy. It turns out it's not super difficult!

Sorry it's sideways. I can't quite remember how the technique entered my awareness, either through researching mosaics or mirroring. A little gelatin, some gold leaf, and some glass. A fine needle to scratch it up, and black paint. I'm going to teach a class on it at Pennsic this summer, which is exciting to me. I've tried a few types of leaf, a few tools to transfer it to the size, and will be picking up a second (larger) gilder's tip this week. It's beautiful to look at and I'm excited to see how I can integrate it into stained glass and mosaic work.

Probably To Be Continued...

Lessons Learned:

• Transfer foil is a lot better to work with for verre églomisé.
• Tiny creases are almost unavoidable with loose leaf, but the gelatin size flattens them out as it dries. The end result isn't perfect but it is much better than what you start with.
• TURN OFF YOUR CEILING FAN. Many people remark that gilding can be done at your kitchen table, and they are quite right. But when you bought a book of loose gold leaf and have the fan on medium, you are going to make a kaleidoscope of tears and gold for a moment. 
• Making Roman Gold, as Rhode is trying, or Byzantine Tesserae as I am, costs a bit! The leaf is not terribly cheap, though you can find it reasonably. She speculates gold foil, not leaf, would work better but it runs $75/5 sheets. 
• Don't use imitation gold. I did this before a year or two ago, without entirely realizing. It was an aluminum-based product, I believe. It turned horrible colors and crinkled up under the glass. 
• I wondered at using silver to do this. I'm told it can work, but my experience with silver stain says it certainly cannot. Ken Leap's book shows an example of firing a piece of solid leaf, and it made a dark amber stain at just slightly higher temperatures than I use to fuse. Further, I've used ground silver leaf in a period formula at much lower temperatures, and it made a light lemon yellow. I'd think 'silver' would necessarily be platinum leaf, which I have not priced or looked at.

Period Vitreous Paints, pt 1: Oops, this worked?

"...using for this ground scales of iron and of another rust found in iron pits, which is red, or else hard red haematitefinely ground, and with these pigments he shades the flesh, using alternately black and red, according to need." - Vasari (Dover translation p. 269)

"...and he gives you a color which he makes from well-ground copper filings;" -Cennini (Dover translation p. 111)

"Take copper that has been beaten thin and burn it in a small iron pan, until it has all fallen into a powder. Then take pieces of green glass and Byzantine blue glass and grind them separately between porphyry stones. Mix these three together in such a waythat there is one third of [copper] powder, one third of green, and one third of blue. Then grind them on the same stone very carefully with wine or urine, put them in an iron or lead pot, and with the greatest care paint the glass following the lines on the board." - Theophilus (Dover translation, p, 63)

Since I've made all but one of the period silver stain formulas I have found, I've decided to try and make vitreous paint. I started by building a frit smasher; it's not the period way to grind glass but it is infinitely easier for some initial tests.

Vasari seems to suggest you just paint with metal dust. Cennini is less specific, but doesn't contradict that. Theophilus clarifies a mixture of metal filings and glass, one part to two..

Just as with my silver stain tests, where I started off with purchased silver salts, I used my frit smasher (aka a frit piston) to smash pieces of scrap clear glass from my scrap buckets. I originally thought that this would require making paints from the same glass you are going to paint on, but nothing in the primary sources suggests that. I've seen reference that say modern vitreous paints are more "glass fluxes" and oxides, rather than actual glass; the latter would seem to be more akin to an enamel as we define it modernly. In this case I specifically sought out pieces from at least two different original sheets to avoid accidentally lining up CoEs.

Scrap glass pieces. I ended up using about twice this. My left hand for scale.

After just a few minutes work, with occasionally shaking of the pile to mix it up for better smashing

For those who don't do much with warm or hot glass, the Coefficient of Expansion relates to how quickly the warming or cooling glass expands or contracts. If you try to use two pieces of glass with incompatible CoEs, they will separate, usually fatally and sometimes explosively. I've generally seen a safe range being only one point in either direction (the common CoEs are 90 and 96 for fusible glass, with 103 also being common to lampworkers making beads. Borosilicate glass/Pyrex used by some lampworkers is CoE 33.) The bulbs I use for my ornaments class are COE 89; we use CoE 90 frit with them with no problem, but 96 is right out.

I rather expected the CoE would be a problem, and would spall or destroy the test chip. I used my frit smasher and generated a mess of pebbles and dust. Lacking anything more specific for filtering, I rolled the material in a piece of cheesecloth to get a grainy powder into a bowl.

Do not inhale this!

I ended up with a wooden bowl of rough clear glass powder. I turned to two purchased bags of metal filings, one iron and one copper. Bother are already a very very fine powder. I scooped a little of each into small wooden bowls using a palette knife, and added a similar amount of glass powder. As I stirred I worried there wouldn't be enough glass to "bind" the metal, and I added more of my clear powder. I ended up, accidentally, with approximately the ratio Theophilus called for. I did some cursory grinding on the palette, but it really didn't help. Testing it with a sable brush showed poor adhesion to the hairs, and the paint that left the brush was fairly poor, very weak with the copper-based batch. The iron batch was much better. As both metals are finely powdered I think I found a better portion of the powder bowl to draw from by luck.

Next go around, I will try to grind them up on porphyry, as period sources call for. I have been confused from time to time on what that means. Over Facebook THL Ian the Green gave me some clearer details from C&I pigment creation. He referenced this video, suggesting the technique at 6:29 and after 8:00 would be helpful. I will try and follow these next.

I placed them on some of my standard test chips, cut to size a binder full of test chips. Because it is glass powder and metal, I suspected that it would require a fairly high temperature to fire these paints; period sources definitely don't have the precise control we have, and in theory this strikes me as much more akin to glass fusing than normal paint firing. I used my standard cycle (which reaches 1250) and waited. And waited. And WAAAAITED.

The chips actually worked quite well. They didn't fire to the smooth and glossy shine of my modern Resuche paints, but they were opaque and well-adhered. I suspected, still, that they would be poorly fixed so I took the chips to my lightbox and hit them with a skewer I use for cleanup work. None of it scratched off.

The iron chip is "psychologically black" rather than optically black; When you see it, you know it's black. Your brain would remember it as black. It's actually fairly grey. The copper based pigment is a pretty color, but I would best describe it as somewhat like dried blood; It's lighter than bistre brown (which reminds me of old tree bark, it's a very dark color but not enough to be perceived as black) and it's a bit darker and more true than tracing brown, which to me has a reddish hint.

Overall, it was incredibly exciting to get working results with these very first attempts. I'm going to pursue more period steps immediately.

As an afterthought, I want to document something Master Avery shared on Facebook. I was totally unaware that you can reverse rust back into iron. The physical structure is destroyed, but the iron is recoverable. This is one way to get good, fine, filings; By using an oxidizer (and I will edit in what he offered, bleach I think) you can get the iron to rust. Then you can easily grind the rust. Putting it in charcoal and heating it appropriately will reverse the oxidation and leave iron. Very, very neat.


Lessons Learned/New Questions:
Holy cow, this worked.
It would work better if ground up more finely
     Use commercial powder/better sieved home made powder?
     Try the porphyry method
Does da Pisa have a recipe? Mappae Clavicula? The Bolognese manuscript? Have to check them...
I did very tiny batches, next time use my sandblasting mask to avoid any invisible dust inhalation.
How is color modulated? How is my modern tracing black so much darker? More iron? Or a darker mineral?
What will hematite look like? Pinkish, for sure, but...
What is Byzantine blue glass? A color, or a specific formula of glass? Byzantium is a purple...

Estelle's Vigil: Scarab Platter

EDIT: I've had to do something stupid to get the text to appear on this post. Sorry!

Estelle has, as one of her personal badges, a scarab (dung beetle) pushing a ball of it's preferred element. It's a reference to her peerage theory, quoted here:

The Dung Beetle Theory of becoming a Peer:

First, you gotta find your shit.

Roll around in that shit a while, make sure it's the shit you want to bring home.

Then, you get your shit together.

You gather it up, make it nice and rounded, polish that shit up so that it shines.

Then, you gotta bring your shit home.

So you spend your time, rolling that shit along.  But because you're a dung beetle, you gotta roll it backwards, which means that you really have no clue where you're really headed... but eventually, after a long while, and with a little luck, you get that shit right where it needs to be.

And that's how you become a Peer.

The End.

She requested a scarab platter on which she can serve truffles during her vigil. She provided a design:

We went through available molds and glass colors to find something acceptable:

(There is an invisible piece of clear for the white in this picture. The glass looks slightly hazy -- to me it's as if someone spilled milk on it and wiped most of it off. It was sold as "cloud" and as a translucent white. It wasn't translucent as I would find out...)

I was a bit concerned about how to fire this one. Before I started this piece I had fired one half of the family badge plate (adjacent post). I think it's issues were closely tied to the irregular layering of the glass (2 layers in some places, 1 layer in others). I added more clear pieces to this blank (what I call the piece as it's being fused, before slumping) to try and keep more consistency.

The piece is not perfectly regular, which didn't surprise me. A little grinding fixed that up. There are some unfortunate lines between the body segments, and leg segments. I knew that would happen but I didn't want to overlap the pieces and potentially provoke bubbles. This picture shows how the white striked. I compared it to a piece of "opaque" fusible white, and the piece sold as opaque was actually more translucent than this cloud glass.

With these platters I progressively slid my firing schedule down from 1300 degrees. I think its near 1230 now, with no change in the hold times. I did that to try and avert "dog boning" especially in the square plates. This helpful advice came from the folks at Fused Glass Fanatics on Facebook.

These pictures show the completed (slumped) platter. The actual shape and depth is not conveyed well, I will try to take a better shot next week. The white is clearly NOT translucent. I used my grinder along the edges to make the shape a little more regular and remove some stabby-bits.

Estelle's vigil: Family Badge Platter

Estelle did not ask for this, but some time ago we discussed the idea of making a matched set of platters that, when joined, would form her family badged (used by her whole mundane household). I decided this was as good a time as any!

The plates feature blue bars on a clear (white) field, with green in the corners (skipping heraldry terminology for non-heralds). Because I use a base layer of clear, I didn't see the need to fill in the second layer with clear. This is the first time I've tried any fused project with clear. I expected that the blue might spread or contract a bit, but I thought it would be acceptable:

HUGE bubble. Right beneath the base layer, not between two. The edge was also very irregular. ALSO, the grey sharpie used to tag the glass didn't burn off as I had expected. So, scrapped it and started over.

This time, I added clear layers in the top. The results fused much more smoothly:

And the slumping went well. Initially the shape bothered me, I thought I was seeing the "dogboning" problem I've had in the past with this mold, and I had been correcting my slumping temperature down to try and adjust. After a couple of days I realized they are fine; the molds have a slight curve in a plane I didn't realize, and the shape is closer to the mold's shape than I thought.

The piece in the top of these pictures had some old kiln wash fuse to the glass. For the immediate purposes, this is fine, but I plan to remake it so it has the clarity of the second (bottom) tray.

Lessons Learned:

• Applied kiln wash apparently has a shelf-life!
• Better results with even layer coverage.

Paint chips

Paint chip samples, to go into the binder. Before firing they always look lifeless and like drawing pastels, in reflected light:

Pre-firing, in transmitted light. I sketched little phrases on them for contrast. The samples are intentionally not blended even:

This was a very beneficial test, in the end, because the transparent green enamel I thought I bought was opaque. That project got sidelined for a bit as I try to decide whether to try it with enamels, or flashed glass. I don't want a leadline where... ah, but that's another post for another day. Three new colors coming this week to test as well.

Running in Circles

A quick observation on cutting circles. After you cut the circle with the tool or method of your choice, and you put in your relief cuts.... tap between the relief cuts. Half the time when I start tapping on a relief cut, I get a piece bisected in two. That does make the rest of the run easier, heh...

Arrows pointing at the successful score, unlike its twin on the bench, bisected. Red dot where I started tapping. Fortunately this is a fusing test.

Same bowls, different

A friend requested some bowls in her household colors, black and gold. With only a week before Val Day I went looking on Delphi's website (they are nearby and ship fast) and found a 3mm black and a 2mm black w/ iridescent gold:

(Unfortunately I think it looks better in photos than reality)

Glass used (Product ID's provided by Delphi, may be proprietary):
B010130 Bullseye Stiff Black 90 COE
B010058 Bullseye Black Opal Gold Iridized Thin
B110038 Bullseye Tekta Clear 3mm - 90 COE

I'm not precisely sure why the gold-on-black is a millimeter thinner, something to investigate later (UPDATE: It's intended for jewelry making, and not general fusing). The blanks are in the kiln fusing at the moment:

I will say, they do look pretty! Unfortunately it ended in complete failure. The blanks looked very pretty, the gold really comes out after fusing, as shown below. I don't normally crash cool, and as such it can take a lot of hours for a blank to cool down. Because I wanted to slump this right away, once the blank was 250-300° or so, I took it out and put it under hot water, which I then slowly changed to cool water, bringing it to room temperature in about a minute. I've done this several times with success. This time, however, I think the plate was hotter than the temperature on the kiln let on; as soon as it hit the hot water a significant crack appeared, between the color and clear layers:

Regardless, I tried slumping it. The results were.... ugly. The bowl was misshapen, cracked, and uneven. It had over-slumped, as well, and almost pooled in the bottom of the mold:

I didn't know if this was some result of the cracking or not, so I tried the second blank I prepared. It was not quite as ugly, but still misshapen. Here they are with comparison to a well-formed Midrealm bowl:

 After staring at a bowl for a long time, I believe this is because of the 2mm gold glass. I suspect it got hotter faster, being thinner, and started to slump prematurely. I slumped another midrealm bowl afterwards just for comparison and it came out fine, with the mold in the exact same place, so I don't believe its a kiln issue. Of course, now I found Delphi has the same glass in 3mm, so there is only one way to find out...

Project Technical Notes: Crown Tourney Assignment

We have won a bid to host the Kingdom A&S competition and Crown Tourney in May. During a feast prep inventory we discovered we need some small bowls and plates. In an effort to jazz it up a little for the eight seats at Head Table, I volunteered to make eight bowls and eight plates featuring the Midrealm pale. These are going to be promptly washed and given back to HT to keep.

Materials:

6" Blank (Bowls):
3"x7" strip of white (x2)   (I'm using an unspecified white Bullseye fusible glass, 3mm)
1.5"x7" strip of red (x1)    (I'm using an unspecified red Bullseye fusible glass, 3mm)
7" square of clear (x1)       (I'm using Bullseye Tekta clear, 3mm, double rolled)

6.5" Blank (Plates):
2.75"x7" strip of white (x2)
2"x7" strip of red (x1)
7.25" square of clear (x1)

The red and white glasses are unspecified because I bought them from my favorite storefront, and the information was not listed or recorded (and the glass quickly cut up before the number on it was noted). The clear was purchased online from Delphi, making the details better known.

Original concept art (plate):

Making the bowls

Cut with a circle cutter so that the blank ideally has proportions of 2.25", 1.5", 2.25" so that the pale (red stripe) is not quite on even footing with the white field (in heraldic terms), although that is not required. This is a common presentation, even if not strictly correct.

My starting position:

 

I use duct tape to bind the three strips together tightly, flip them over, place them into my circle cutter, and if the glass gods are kind, I end up with a circle. Remove the three pieces from the duct tape. The cuts on the red strip are so subtle I pop them easily with my running pliers. The cuts on the white stripes are much more substantial; I make perpendicular relief cuts like I would would with a solid circle and tap them out with the back end of my glass cutter. This seems to be more reliable than the idea of slowly applying pressure on either end of the cut with running pliers.

I cut a clear base using normal circle-cutting techniques. Assemble:

I use the standard "small piece" fusing schedule my kiln came preprogrammed with:

300°F/hour to 1000°F, hold 0 minutes

FULL/hour to 1350°F, hold 0 minutes

500°F/hour to 1425°F, hold 10 minutes

FULL/hour to 950°F, hold 30 minutes

The fused "blank":

I slump it using a mold from Slumpy's, using the standard "small piece" slumping schedule pre-programmed in my kiln:

300°F/hour to 1000°F, hold 0 minutes
500­°F/hour to 1280°F, hold 20 minutes
FULL/hour to 950°F, hold 30 minutes

The finished bowl:

Repeat seven more times....

Making Plates

The process is much the same as above, but the sizes of the strips are different. After cutting with the circle cutter the desired end proportions are 2.5" white, 2" red, 2.5" white (for a 7" pattern). I discovered that I mis-remembered my past measurement and my plate mold is actually 6.5" in diameter. A quick check during a holding cycle showed that the extra .25" rim didn't droop like I feared, but slumped successfully. I'm not sure if I will stick to these numbers or go ahead and make a 6.5" blank next time, but I suspect the latter, though the end result was fine.

Same fusing and slumping schedules used as for the bowls.

The completed set:

Not all it's cracked up to be...

An interesting result from yesterday's firing; while cutting the circle for the blank, one white strip bisected accidentally. I didn't worry about it, since I was about to fuse it into a solid piece anyway. Even doing so, there are telltale signs:

In this picture you can see little dimples where the crack was, both at the inside edge (where the crack met the red stripe in a 3-way "joint") and at the outside edge, where it looks like clear glass filled the gap instead of white.

Holding the piece itself you can see the crack is lighter in color, although the surface is smooth. It looks like the clear base fills in the gap instead of the white, and while there doesn't appear to be any weakness, it is visible.

The fourth blank had a similar issue, a small but not insignificant chunk popped off a white strip. The "heal" is noticeable, as before:

(Update, a few days later):

Another variation of this turned up when I made the plate, though you can see it in the last photo as well. Fusing is no replacement for good cutting and fitting!

There was a slight error or shelf present and the red stripe was not in as solid contact with one white piece as it was the other. As a result, on close inspection, you can see how the clear again made up the difference.

Manufacturer's Lie

Very pleased with today's fusing:

The first blank I fired, and immediately slumped into a bowl, picture here for sake of a complete record:

I didn't think to measure the finished blank to see how much the size changed. With the second one I did measure it, and found out it actually shrank slightly!

My understanding from a Bullseye Technote (I think) is that warm glass wants to be 6mm thick, and it should contract or expand to try and reach that level. The glass base I'm using is 3mm, and the colored glasses are 3mm. I expected no change.

M. Sigulf suggested that the rolling process actually makes the sheets a little thinner than the official spec, and as a result it contracted a bit. Fortunately, with 6" disks and a 13" kiln shelf, I can actually get two blanks fused at once and save some firings. Unfortunately the plate mold we are using is 7"; It will be back to single firings for that, unless I want to make 6" plates instead.