Friday, April 1, 2016

The Arms of Baroness Laurencia of Carlisle, OL

Hello! It is a few minutes before midnight on the eve of Laurencia's elevation to the Order of the Laurel. I am scheduling this to go live early in the morning; I'll post it to Facebook mid-morning when it should be safe! Let me apologize in advance for the inevitable spelling and title screw-ups! Also please note you can click on pictures to enlarge most of them. -Brynn


I used to work with Laurencia and her husband, Eirikr inn havi four or so years ago. A few months ago he messaged me on Facebook to ask if I could do her device for her upcoming elevation.





The original image he provided


Knowing her elevation was to be at Ice Dragon in April, I sat it on it for bit. Too long, but ok in the end! I seem to recall being told Laurencia is part of the "14th century mafia" so I wanted to pick a design that was appropriate to her period. Looking at extant panels from France and England, I found several of an armiger's device set in "plain glazing" or a window of clear glass. Frequently we do quarries with more acutely angled points, diamonds like the suit on playing cards.



Like these! Image courtesy of the CVMA


In several windows of this time, however, I saw they were the 90-degree style diamonds. The more acute style seems much more prevalent in late-period windows, I'd like to dig into those changes sometime.

At one point I thought about setting her device in a ring of laurel leaves, but I found it very difficult to do so within a reasonably-sized window. I tried scaling my pattern up from 12 to 14 to 16 inches square, but I couldn't find proportions that were acceptable. Either the ring was too thin, or the device too small, or the combination awkwardly placed in the pattern. I eventually dropped that plan and just focused on her device.

I opted to used all mouthblown ("Handmade") glass for this. On hand I had sheets of Krosno (from Poland) and St. Just (from France). I had never mixed them, so this was the first opportunity I had to note the difference in their compositions:


The edge-on view gives it away. The green is caused by iron impurities, though a few sources claim some copper content can do that as well. Ensuring the iron is kept out, or adding selenium or lead, causes a clearer glass as with the other brand here. If I'm not mistaken, it's the St Just that is green.

The flashed glass I used, red flashed on clear, is of unknown provenance via THL Molly Sotherden, but despite hearing of it's existence I've yet to find machine-rolled flashed glass. Looking at the irregularities, I feel very confident it is mouthblown as well. I learned during this project that flashed glass can be a striking color (See Lessons Learned section below). Flashed glass has a thicker base layer of one color (usually clear) and a thinner layer of another. It is one solid sheet of glass with two distinct sides. Originally this was done because otherwise some colors were too dark to transmit light (red is the best example). A sheet made in the typical way would appear black. Giving a thin layer of color to a clear sheet allowed the red to shine through and remain strong enough to use. In the 14th century it became well-known that you could remove the colored layer and add extra detail without adding leadlines.

At this point in time, most glass cutting is done with a dividing iron (a red hot poker used to incite thermal shock in the glass to give it a crude shape), which can be seen in my post here and the video to which it links. The shape would be refined through a grozing iron (I now use a proper grozing iron made for me by THL Kendrick Cameron, but my original one can be seen here). About this period in time, diamond-tipped cutting tools are becoming known in Italy. I own an antique diamond-tipped cutter and used it a little for this project; unfortunately it is rather temperamental and I wasted half a sheet of clear glass trying to make it work. As a result the majority of the cuts use a modern carbide-wheel cutter to save glass/money.


My modern cutter, and my antique diamond-tipped cutter

Period sources talk of either abrading away the flashed side, or using acid to etch it away. The acid called for in period is generally not strong enough to etch glass unless it is of very poor quality (and hat tip to my Laurel, Mistress Kirsten Thorsteinsdottir, for that fact). Modernly we can use a stronger acid, power tools, hand abrading, or sandblasting. Sandblasting and acid end up with very similar results. Having tried all of these options in the past, and wanting a certain "hand abraded" look on "power tool" time tables, I abraded it using an engraving tool. It is less drastic than a dremel, and after firing I think it looks excellent.




The water bath is probably not period, but we prefer to avoid death by silicosis today! The picture on right is the piece before fire polishing.

I applied vitreous paint to the bird using a miniver brush, as called for in our primary source texts. Period formulas for vitreous paint call for crushed glass and mineral/metal oxides for color. Modern texts reference using glass fluxes and components, rather than actual glass, for making paint, however the oxides are still in use. I fired the three pieces, bird and two halves of the ermine section, in my modern electric kiln. My tests on proper period kilns are still forthcoming and, again, the glass is expensive to waste!


The central/bottom portion, after firing



The entire device, fired. I aligned the ermine spots to coincide with the lead line to try and mask it a little. Fully period cutting tools might have been able to get that steep inner angle cut out of one piece of glass. Might.

I cut the background of quarries and got stuck worrying about the next steps. Obviously lead came would be the period technique, and cast cames at that. I would have to use purchased milled cames, but my skillset with came is very rusty, and it's not as strong. In order to have a strong, lower-maintenance, and better looking end product I opted to use modern copper foil methods to assemble the window. That would be the biggest concession to modernity but I feel it was/is the right call.


The glass, all cut.


The glass, all foiled!


A pretty close-up 



The completed and framed panel

I put the completed panel in a wooden frame, which is called for in our primary sources. I added modern hanging hardware (eyelets and rustic copper chain) for Laurencia and Eirik's convenience. I hope that it arrived unbroken and that it is only one of many beautiful things she gets on the day of her elevation!


Lessons Learned



1) Diamond-tipped cutters are finicky!

2) From a discussion with Conor O'Ceallaigh, after fire polishing some non-yellowing lacquer could smooth out the texture further. I had several kinds on hand, but I wanted the abraded texture to remain.

3) I need more practice with framing stock. These pieces fit fine when I cut and test fit them, and held while I handled them after gluing. When I added the support brackets on the back, the joints popped a bit and gaps appear. OI!

4) This is only the second time I had an issue with a glass color striking on me, and the first was understandable as it was a green enamel. My sheet of red flashed was in two pieces; I knew one end was a prettier red and the other end was an odd brownish-purple color. I couldn't find the larger sheet with the better end, only a significant piece from the brownish-purple side. Remembering a funny story involving this piece two years ago (which I only told on Facebook, I'll add it here later today), I checked it against two different light sources. Sure enough, backlit by an incandescent bulb, it was beautiful ruby. Against fluorescent or sunlight, purple-brown.

Color being what it is between devices and cameras, this is the best I could do.

Since yellow light turns it ruby, I thought I could hit it with some silver stain to bring yellow into the mix, and have a piece that was actually red. I fired a test chip and when I pulled it out of the kiln, I was shocked to discover I couldn't see where the stain was. I was a bit disheartened and considered plans B (enamel) and C (piecing it together). Then I realized I couldn't tell where the stain was on my test chip because the entire piece had turned ruby.

This is actually the unfired piece from the picture above lit by a different lightbulb, but this is how the finished piece looks in all light as you can see in all the other pictures.

That was fascinating and a surprise!

Sunday, March 27, 2016

Archery Prize: Pheons

Details to come shortly! An educational lesson with Molly that churned out the first of a few archery prizes:



Monday, February 15, 2016

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...