Medieval Glass

Shop Repairs, Furnace Lust

2008-07-11T16:42:29Z

Owning even a small glass shop is definitely a constant process of re-designing, maintenance, and improvement. Sadly, right now we are once again in the maintenance stage. Last Saturday the electric furnace stopped staying hot. Hopefully it just needs new elements, so I ordered some today. Luckily they are only $25 each plus shipping, so not terribly expensive. It does make the 170 lb electric furnace with molybdenum disilicide elements seem even more attractive. Now if I just had an extra $8000 laying around to purchase it with... We had Cheyenne as an instructor in our goblet class last Tuesday evening, and he works days for the company that makes the furnace I want. We had expressed our interest in the "small" melt furnace at the conference and he asked if we were going to get one. I wish... maybe in a few years. Soooo nice! And if we wanted the moly elements (they supposedly never burn out which is the big attraction), it would cost as much to make the small size furnace as to buy it. Elements now has one of these that was donated for the GAS conference. They are using it s a color pot and I got to try it out a few weeks ago. Here, have some glass furnace porn:

Pictures & Notes

2008-06-17T17:20:38Z

Transcriptions of glass blowing notes:

6/7/08
I small blue claw beaker, used Gaffer 26, cerulean Blue. The glass seemed not hot enough, my piece ended up too tick, so the claws ended up being solid rather than blown. Decided to make some more small punties for bit work since they seem to be a good size for a ot of the things I want. Second cup looked like Kathalu's back side, so considered it blown claw practice and trashed it.

6/8/08
Had time to do one pieces, so I made a class beaker with Gaffer 30P Jade Green. It turned out all right, despite some of the bits not being very nice. I took them anyway and considered it practice. The overall cup actually looks quite nice. Note: Sold to Hrafnir & Svava! :-)

Pics of the two claw beakers from 6/7 & 6/8:

6/9/08
I already posted about this day but here are some additional bits of info and pics. I did my first attempt at a linen smoother for Inga. The shape took a little futzing with, but was pretty easy to get. I think it would be nice to have a marver on the floor ala medieval glassblowing pictures, so am going to try to set one up soon. I ended up using he table marver and the paper a little bit. I need to remember to flip these over once they are in the annealer. I flipped this one, but after an hour or so as I didn't think of it earlier, and it had slumped a little so will need some cold working. I used Gaffer 30P Jade Green. I took six gathers of glass, and colored layers 2 - 6 with green, so that it would have a nice dark green color. When held to the light you can sort of see the layers, but it looks pretty good overall. Now I just need to do a little cold working.

Linen Smoother:

I did two beakers by myself, re-using the blow pipe as a punty. The bottom broke out on the first since I get the blow pipe too hot and stuck t on way too well (maybe if I had pulled it back and jacked it like a sculpture punty???). The second turned out great! The diciest bit was timing knocking it off and opening the annealer door so that I didn't let the stuff inside cool down too much. The ring mark on the bottom of the beaker looks very medieval, and it worked so well that I feel my theory about hem often re-using blow pipes as punties is probably right-on.

My first solo-blown beaker:

I as pretty careful about wire brushing the pipes and punties, and trying t keep them free f scale, yet I still ended up with some flakes from the iron pipes on the glass. I wonder how they dealt with this in period. Kicked the apprentices if they didn't keep the pipes in good shape? Hmmm. We are now trying a very light borax solution in the pipes to see if that helps, but it doesn't seem like something they would have done. Or maybe they did have some secret... I need to go visit a primitive glass house in Egypt or something and see what they do with their pipes. In the mean time, getting a few stainless pipes might not be a bad plan, even if stainless is $$$$.

Blowing Solo

2008-06-09T22:56:42Z

Today has been my first day "blowing solo" at my home glass furnace, and it is far less daunting than I thought it would be. SO far I have made two pieces, a prototype for a solid viking style smoother (thank ya_inga for that one), and a basic beaker. The smoother was pretty simple - sort of a slumped pancake shape, made from 5 gathers of glass, with jade green on some of the layers, I had to fiddle a bit to get what I think is the correct shape, but it is basically a funky-lookin' paper weight. The beaker went pretty well, though the bottom did end up breaking. I managed to create the correct shape and a nice not-to thick body all by myself, then tried out what I think is the most typical way of puntying up medieval glass - I re-heated the blow pipe and stuck it back onto the bottom of the cup as a punty. This worked really well, except that I forgot to bring the tweezers over and it got off center. I did manage to correct the center, but in the process I stuck the glass on a bit too well and ended up breaking out the bottom in the annealer because it just didn't want to pop off the punty. Oh well, for a first try, I am pretty impressed still. I am currently taking a break, and plan on going back out in a while to give it another shot. If things keep going so well, I should be able to do a lot of things by myself - en exciting prospect! I am going to try to transfer my glass blowing notes to this journal, and document what I produce. I am hoping this will help me keep better track of colors used and techniques since I am bad about loosing sketch books and mis-placing notes. Now I just have to find my camera...

Recycled Glass

2008-02-26T08:12:59Z

Well, I haven't posted in this journal for a while, so it is about time!

Last Sunday we melted a batch of glass from my ex-employer, Anne Garrision Design. The glass was basic picture glass as used in frames, etc, and all the same type from the same place. It ended up having a slight blue tint, and didn't blow too badly. Dad and Lisa both thought it was a little thick and quicker to harden up, but part of it was getting used to the color indications being different than with perfectly clear glass. I would say it was a bit easier to work than the Roman glass I tried, but a bit closer to it than our normal batch and cullets that are formulated for glass blowing. It is nice to know that we can successfully recycle glass. I sort of want to try a mixed pot of blue bottle glass to see how funky it is, but not until we have an extra crucible around. Also good to know that a good way to get a less-pure and more "medieval" color is just to buy a bunch of window glass and melt it. ;-)

On a slightly different note, we are supposed to be on the Kingdom A&S schedule for having a meeting of those interested in forming an An Tir glass workers guild. I haven't seen a specific time yet, but when I do I will post it.

Also, the GAS (Glass Arts Society) is having its yearly convention in Portland this summer - very cool! Expensive, but neat. I am planning on attending. I also just joined the Oregon Glass Guild. I got my membership card in the mail on Friday.

It has been a while, but there is glass news!

2007-09-15T10:00:30Z

The new (propane) glass furnace is proceeding apace! In fact, we just had a test firing! It got hot, hot, hot. And now dad is taking the thing apart and doing some more structural work on it, since we know the burners are way more than sufficient for the job of heating up the furnace.
I need to remember to bring the camera over tomorrow so I can take some pictures of the furnace in progress. The design prototype drawings were by me, with the working model refined and built by dad (with occasional small amounts of help from Ed and me). It is designed to come apart and be portable, with the hopes of bringing it to an event some time next year. It is also designed to be similar to the daub beehive shaped wood-fired Roman and Medieval furnaces, but using modern materials and fuel so it will be portable and can be manned by one person. It currently draws propane from four tanks and utilizes two burners, though I think one burner would do the job just fine. The beehive shaped top works really well - it currently doesn't have a front door, so when the burners are on it is possible to look in the front (from a goodly distance!!!) and see the fire swirling in a circular motion, shaped by the "beehive". There is a vent hole in the top which we are hoping to use for flameworking beads and core vessels and the like. It seems to get a fairly good jet of flame coming through, so I am hoping that it will work - we certainly know enough talented bead makers to test it out! The top beehive shaped section comes off (it has handles built into the frame) and consists of fire brick that will be covered with a sand, perlite, and furnace cement mixture. The bottom section is a metal frame table with a top of firebrick covered with sand and furnace cement, with the two burners mounted in it. Ideally, when the furnace is complete, it will be possible to sit in front of it and work, including gathering from where we are sitting, just like I was able to do while visiting the Roman Furnace Project. One modification that has already been made - moving the burner controls. They used to be at the bottom of the burners, just below the furnace door opening. When dad leaned down to turn on the second burner during the first test fire, mom and I both saw his hair start to smoke!!! Much yelling ensued, since that baby is REALLY loud when both burners are on. The burner controls are now back closer to the propane tanks.

We have a floor!

2007-02-05T06:50:53Z

The Glass shop now has a cement floor! Jamie and Catherine (cat) came up from Eugene and helped my parents, Ed, and Hank and I pack gravel, and pour the cement slab. And it kicks butt, especaially for the first cement work Jamie, Cat, Hank, and I have ever done! Hank and I dug up a bunch of the floor last weekend, then Mom and Ed hauled it out during the week. Then Dad and Ed made trailer runs to get gravel and cement, while Jamie, Cat, Hank and I spread, packed, and smoothed. Now I just need to go in and sand the top before it is completely cured. Woot! In a week or so we can start moving stuff in! I have several items lined up to cook in my glass kiln, which will be going in first. And I can finally hook up the sand blasting cabinet. Woot!

Did I mention chickens?

2006-12-19T19:12:31Z

Notice the marvelous gilded chickens that I added to the capola of our glass shop! Also pictured is Edwardus Honestus (aka Ed).

I finally put up some photos!

2006-12-19T19:08:39Z

I now have some glass shop pics on my flickr page! There are pics of converting my parents' carriage house into a modern glass blowing shop, and of the area where we will evenually be building the medieval glass furnace. Of course, the pics aren't entierly up to date, I need to take more. This last weekend Dad, Ed, Cat and Jamie got doors onto the shop, and hanksan and I started putting in the electrical. Dad has been putting together our furnace, and I also need to get some pics of his temporary blacksmithing shop, where he has been spending a lot of time lately. Or current goal for the modern glass shop is to have it up and running in the next month (crosses fingers).

The roof is sheathed!

2006-09-28T07:43:17Z

Today Ed, Dad and I got the rest of the sheathing done on the roof of the modern glass shop, and also got a side and a half covered with tar paper. Go us! It looks SO much better, and is not even done yet! Now we actually have a chance of getting it water proofed by the time real rain starts coming down! We also discussed what we are going to do for front doors to the shop and for evening out the floor. We have decided that we will have two sets of 4' doors in front where the weird garge doors are now. We will probabaly do a packed dirt floor on the half that is non-cement and currently at a lower level. The dirt will bring the level up, and yet we will be able to clear glass off of the packed dirt, which would be a lot harder to do with gravel. None of us feel like pouring concrete, but we can always go back and do that later if we decide we need it.

More roofing

2006-08-16T06:53:50Z

Two more sides of the future modern glass shop roof have been stripped of many layers of decaying roofing. Lots of ants, larvae and spiders uncovered. Found more rot than we initially hoped, but it is fixable. We still have a quarter of the roof left to strip, then we need to replace the rotted battens and rafter ends, then put on the plywood sheathing, then we can actually put roofing on. Long hours ahead, but progress is being made.

We have a building!

2006-08-04T04:19:28Z

I still need to post the pics, but there is indeed now a structure under which to put the glass furnace! Woot! Ed, Cat, Dad, and I also started taking the 6 layers of roofing off of the garage roof today. It is about 1/4 taken off. This is the garage that will be the modern glass shop and where we will be testing out glass recipies. I am going back over there on Saturday to continue work on the roof.

Building and Books!

2006-07-28T01:47:03Z

Next Tuesday morning a structure will suddenly appear in my parent's field which will soon contain a medieval style glass furnace! And I got a book from Pastiche with an article about a renaissance convent with a glass shop including archaeological drawings. AND I just got the 2 volume set of analysis of glass! All is good. I am going over to the parent's place on Monday to help with site preperation for the building.

medievalglass @ 2006-07-09T07:57:00

2006-07-09T15:12:37Z

On Friday we went down to Brooks to look at metal carport/ garage structures. My parents managed to fiond a place that makes very nice ones that are actually affordable called Pacific Steel Metal Buildings. We decided to get a 18' x 21' with 8' walls in the "a-frame" style (It has a normal roof line instead of those weird arched on the corners carports you sometimes see - this is more like a small metal pole barn). It ended up costing $1495 including anchors, delivery and set-up, 2 extra feet of height, and vertical roofing. It is even going to be a nice color - the roof will be earth brown and it will have evergreen trim. I was happy that we only managed to nickle and dime it up to that price from the base price of $1195 - go us! This will go over the medieval glass furnace.

Yesturday we went down to look at metal roofing in Woodburn, on the hopes that the hardware store down there might have more selection than the more urban ones to the North. Metal roofing is expensive. On the other hand we wouldn't need to put sheathing over the slats on the roof after we strip it down. We will have to think about it.

Book!

2006-06-27T03:11:19Z

My wonderful mother just ordered me a copy of Robert Brill's, Chemical Analysis of Early Glasses, from Whitehouse Books! This is the 2 volume set on which Mark Taylor has based a lot of his glass recipes. If anyone else wants to get me a present, I am also in the marker for a copy of, Tout Feu Tout Sable, by Daniele Foy and Marie-Dominique Nenne. It has several pictures and descriptions of archaeological excavations of glass furnaces. I got another email from Mark today in which he passes on contact info for some people who have done more work with pot ash glass. He also passed on the info about the modern and roman style glass pots they use.

The pots we use in our modern furnace are made from a mix of kaolin, molochite (calcined kaolin) and ball clay. We make a slip and slipcast them in a large plaster mould. The pots are dried and stored, then fired in the furnace to 1400*C when necessary.

A friend of ours made the Roman pots, and it was a terracotta clay grogged with sand. I would think that they were fired to about 1050*C, but they will fire to a higher temperature when in use in the furnace.

Too Hot!

2006-06-26T23:00:34Z

Is is way too hot to work outside. We were going to get more wood on Saturday morning, but we discovered that the trailer needs some other repairs. Between that and fitting Elric's jeep out so that it can haul the trailer, we ended up not going to get more wood, as it was far to hot by the time we were done. Hopefully we will be prepared for the next batch o' wood though. And the maple should be drying out nicely on its black plastic sheets.

So much wood, so much work

2006-06-24T05:05:18Z

I went over to my parent's place this morning at 9am, we got a new battery for the suburban so it would start, then went up to SE 162nd to pick up some free firewood that was advertised on craigs list. It was Maple, so very nice, and we managed to fit a bit over a cord into the trailer and the back of the suburban. Thank you Justin! (Juston ownes the property on which he recently had to cut down the eight Maple trees because of some insidious creeping rot). Not only did we get some nice sized pieces, but we have a whole bunch of log chunks that weight well over 100lbs. Very cool, also a LOT of work to more about. But if we don't split them all, some will make nice utility stumps for various purposes around the furnace and also will work well as anvil stumps. On the way back to my parents' place we noticed that the tires on the trailer were low, so pulled into a gas station to fill them up. Just as we entered there was a loud POP and one of the tires popped off of the rim. Much grumbling and jacking up of incredibly full trailer ensued. Mom was nearby so she came over to meet us with her car, so we didn't have to detach the trailer, luckily. They took the tire and rim over to a tire shop while I guarded the suburban, got a new tire, we put the new tire on, and finally we got under way. After the fun of unloading next to the proposed glass furnace site we where all exhausted. And it was already 5pm and HOT. But the first load of wood is in! And we are going back tomorrow morning for load #2.

Recipe For Blue-Green Roman Glass

2006-06-20T17:50:59Z

Mark, from the Roman Glass Maker just wrote me back with

Recipe for Blue-Green Roman Glass

Raw materials

SILICON DIOXIDE (HIGH Fe) SiO2 69.1527
SODIUM CARBONATE Na2CO3 31.8019
POTASSIUM BITARTRATE KC4H5O6 0.0591
POTASSIUM CARBONATE K2CO3 1.1604
POTASSIUM NITRATE KNO3 0.0000
CALCIUM CARBONATE CaCO3 11.7369
MAGNESIUM CARBONATE MgCO3 1.9636
MOLOCHITE SiO2 + Al2O3 3.3332
IRON OXIDE Fe2O3 0.9500
TOTAL: 120.1577

medievalglass @ 2006-06-19T14:11:00

2006-06-19T21:11:33Z

I recently visited the Roman Furnace Project in England and was inspired to start a similar project focusing on medieval glass technology at my parent's property in Wilsonville, Oregon. This journal's purpose is to chronicle the progress made on the furnace and associated projects.

So far we have been working like crazy to clear their huge piles of blackberries in order to make room for the temporary structures which will cover the furnace and wood piles. Yesterday we succeeded in clearing about half of what was once the garden plot, an area of about 100' x 130'. The we set up the top section of a portable garage, which will be used to cover the first wood pile. This used to be the frame for my red pavilion and is a 10' x 20' structure. We need to purchase or find some metal conduit to use for legs, as he legs I was using were wooden. We also want them to be long enough that we can bury them in the ground a few feet, making the structure semi-permanent. We plan on using a similar structure to cover the furnace project. Other progress includes having cleared the back and part of the side of my parent's detached garage, which we will be turning into the modern glass studio. This is also where we will be doing test melt of glass recipes and melting the glass which we will break into frit to use in the furnace. Once the sides of the garage are cleared we need to re-sheath and shingle the roof,then we can start on the inside of the building. The garage is a 18' x 20' structure approximately.