Revision as of 15:08, 26 October 2014

Glassworking - General

Summary

This is a kiln and hot torch to work with soft glass - fusing and forming rather than blowing although if there's interest in the latter let us know!

These are Category Red tools: induction is mandatory.

Owners

• Tom Oinn
• Renee Chow
• ST

Training

To get trained on the glass kiln and torch and be added to the qualified user list, you will need to arrange for a training session with one of the Owners.

If you'd like to arrange training, please see:

• Glassworking Training

Health and Safety

Formal Risk Assessment: Glassworking

Glassworking involves both sharp, fragile raw materials and extreme heat. Most risks are obvious - sharp glass can cut you, and the hot torch and kiln can both burn. There are, however, a few non-obvious risks to be aware of:

1. When working with the flame your glass will be glowing red hot or hotter, but very shortly after you put a rod down to work with something else the glass will cool to be visually indistinguishable from glass at room temperature. It may at this point still be hundreds of degrees centigrade! Do not pick anything up while someone is working at the torch without asking, you like your skin and want to keep it.
2. Glass rods can stress-crack at the tip when heated. Point rods away from you and always wear eye protection - the glass won't travel far but you don't want it in your eyes.
3. Some substances release toxic gases when heated to high temperatures
4. For glass fusing, use glass that is designed for fusing. Please check the COE and compatibility of your glass.
5. Please do not place flammable items near (<12 inches) the kiln. Please do not move the kiln closer to the walls.
6. Wear dark grey safety glasses provided when looking into the kiln. Wear the blue safety glasses when working with the flame.
7. Do not breathe in fine powders. Wear a dusk mask when mixing shelf primer, reapplying kiln shelf etc.
8. Wear eye protection when cutting glass. Please clean surfaces afterwards with a damp paper towel. The tiny glass shards you get when you cut glass may be invisible to the eye but can be dangerous if it gets in your eyes.

Other risks will be covered during training - working with hot glass is perfectly safe as long as basic procedures are followed.

Equipment

Our kiln is a Paragon SC2 kiln with an included bead door and window. This kiln includes a controller capable of multi-step programs with controlled rate heat up and cool down cycles. It has a maximum temperature of 1100 degrees centigrade, enough to fire some metal clays and work with most kinds of glass, but not enough to act as a metal furnace. There's an instruction booklet to use both in the box below the table.

In addition to the kiln we have a HotHead gas torch, along with the appropriate connection kit to run off bulk Propane gas rather than the normal MAPP cylinders (these burn slightly hotter, but are much more expensive as they're not available in larger quantities). The torch is mounted on a height and angle adjustable stand suitable for bead work when sitting on the low stool that should be lurking around the glassworking station.

For bead working we have a variety of mandrels, bead release that can be cooked in the flame and a wedge shaped graphite marver. Also a pot of vermiculite to slowly cool your beads so they won't break.

For art glass and strip-work we have a set of cutting tools along with a slump mould for making very small (9x9cm) glass bowls. Plus Bullseye GlasTac for sticking your pieces of glass together before you put them into the kiln. Please use only glue that is safe to heat to high temperatures - superglue, for example, should NOT be used as it releases cyanide gas (yikes!) when heated to high temperatures

It is important that these tools remain exclusively used for glass, please resist the temptation to use the cutters, pliers etc for other materials!

Glass Stock

We have a selection of glass rod, sheet, stringer and frit.

The large pots of glass are bought as a random selection for about ten pounds per pot, they consist of offcuts of bullseye COE90 (coefficient of expansion, only important in as much as all glass in a particular piece should have the same number to prevent explosions!) in various thicknesses. Bullseye COE90 glass will tend to form 6mm thick sheets due to surface tension so stack your strip-work to that height.

In addition to this we have a small amount of specific colours of bullseye COE90 glass currently in clear 9x9cm sheets and larger plates of Makespace colours. We can buy at a discount from a couple of online suppliers even when ordering small quantities (a side effect of buying all the kiln and other hardware in one go!) so post to the list of you want anything in particular and we can order it.

For bead making we have a set of clear and a set of mixed coloured COE90 rods, along with tubes of frit and a selection of random stringer (1mm thick rod) glass for decoration. Prices for these are TBD, but will be printed on a sheet near the glassworking station when determined (something in the order of a pound per full rod, that would work out as around 20-40p per medium size bead, each of which would take about half an hour to make).

Location

The glassworking kit is in the corner of the main workshop nearest the stairs up to the cafe. Please keep work to the area covered by the steel sheeting - we're not working with enough material to cause a serious problem otherwise but it helps keep everything tidy. As it currently stands the station is only suitable for one person, or two if both are working together. It would be asking for trouble to try to have someone using the table to cut glass at the same time as someone was working with the torch, so please don't!

Scheduling

Unlike many pieces of equipment in Makespace the kiln requires a considerable amount of uninterrupted time to run. We don't have a formal booking system in place, so for now I suggest you email the list if you propose to use it. For example, if you're doing bead work you will be spending between half an hour and two hours (depending on how many you're making) using the hot torch, with beads being placed in the kiln at a holding temperature while the others are worked in the flame, then running an annealing cycle which will cool down under computer control for a couple of hours, then cooling to ambient before the kiln becomes available for other users. It should be possible to get two runs in a day, as long as the first is done in the morning, but no more than that.

The kiln is a model which should be possible to leave unattended once you have set the digital controller to run a specific program. Before firing make sure you sign post that the kiln is hot, that there is nothing flammable near the kiln and that there is about 12 inches gap between the kiln and the walls. Please check the firing schedule - don't assume it is set to any previous settings. If you are doing anything new/are unfamiliar with the kiln, please ensure that you can be in the space for the duration of its active firing cycle - it's fine to leave once the heating elements are off and the kiln is cooling to ambient but please hang around while it's actually firing. If firing overnight please come in the next day to turn the kiln off.

How tos

Do not use the equipment if you have not been inducted! If in doubt, consult the Kiln manual(s), and/or speak to one of the owners (or other trained users)!

How to make glass beads

Preparation

Smell if there's any gas around (leak from the gas bottle)... If not:

1. Fire up kiln
   • Turn on at the manual switch; wait for "IdLE" to appear. If it says "CpLt" press Start once.
   • Use Programme 1
     • press Review; if it shows #1, then simply press Start twice
     • if it shows some other number, consult the manual how to start Programme 1! [to be expanded]
       • From IdLE press START (the left button) Use the Up Arrow (not the Down Arrow) to select a firing program - in this case Program 1 for annealing glass beads. Press start until the kiln starts displaying the temperature of the kiln. The clicking noise is normal.
2. Get bead release to correct consistency
   • The bead release dries out over time. If it is too thick and lumpy you need to add water to it.
     Screw on the lid and shake the bead release well to get rid of all the lumps. It should be the consistency of a thick smoothie.
3. Get everything (mandrels, tools, water bucket, glass) ready and laid out, so you don't have to bend over the hot flame to fetch it later

The final firing temperature is ~530 degrees; the kiln heats up pretty quickly, so you should be able to start working on the glass bead already.

Flameworking

For each bead:

1. Coat the mandrel
   • tilt the bottle before you dip
   • dip only once, turn the mandrel while it is still in the bottle without touching the sides of the bottle
   • pull out the mandrel without touching the sides of the bottle
2. Turn on flame
   • the two 'outer' valves open counter-clockwise, but the 'middle' valve opens clockwise.
   • don't put the lighter directly in front of the nozzle, but slightly below/to the side
   • adjust gas flow so it doesn't sputter but doesn't have a loud "windy" noise either
3. Sit on the small stool, resting your elbows on your legs; rest the mandrel on your little finger, and use thumb and index finger to rotate it
4. Dry bead release & heat mandrel in flame
5. Heat tip of glass rod evenly
   • the hottest part of the flame is just at the tip of the bright blue (inner) cone
   • beware of splinters (thermoshock) -- point rod away from you and other people!
   • if applicable, straighten rod out again before putting away (so the direction of thermoshock is predictable)
6. Gently add molten glass onto mandrel - it is easiest to keep your glass rod still and rotate your mandrel away from you, rather than keeping your mandrel still and trying to roll glass onto the mandrel
   • the glass rod should be in the hottest part of the flame, the mandrel slightly further away
   • do not apply any significant force -- this will pull off the bead release
   • do not let the glass touch the mandrels directly (where there isn't any bead release)!
   • create overhang to prevent pointy bits around the hole of the bead
7. Things you can do with the bead:
   • add little splinters of glass (put on metal table, scoop back into tube afterwards)
   • use the thin glass rods to draw lines and shapes
   • use a thin mandrel to marble/'paint' (e.g. spirals) between glasses of different color
     • if glass remains stuck to the mandrel, get it red hot and dip into the water bucket; repeat as necessary
   • e.g. silver foil to change color of glass [to be expanded]
8. When done, move bead to colder part of flame till it's no longer glowing red; turn off the flame and insert mandrel into kiln
   • make sure not to touch the walls, and especially not the thermocouple at the back wall!

Repeat as needed for as many mandrels as fit into the kiln.

Wrapping up

When all the beads are in the kiln:

1. Press the Skip Segment button, and then Start
2. Stick around till the cooling process has finished, and the kiln returns to "IDLE" (should occur at around 370 degrees Celsius, after around 45 minutes)
3. Turn off kiln, and add note saying it's still hot (which it is!)
4. Leave mandrels in for another few hours (the next morning if you worked in the evening) so they can cool down to room temperature
5. Don't forget to pick up your beads later to make space for other people!

Alternative method: Vermiculite

If the kiln is in use for fusing, an alternative method of cooling your beads slowly is to place them into the pot of vermiculite as opposed to the heated kiln. The vermiculite traps air around the bead, stopping it from cooling too quickly. Although for small beads this is usually sufficient to prevent the bead from cracking, to be on the safe side, you will need to anneal your bead in the kiln afterwards. (Shops will generally require you to anneal all your beads before you sell them)

1. When done working with the bead in the flame, move bead to colder part of flame till it's no longer glowing red
2. Turn off the flame, use the marver to push aside the vermiculite a little and plant your bead into the vermiculite.
3. Leave it in there until it cools to room temp (how long this takes depends on how big your bead is, but overnight is probably the safest).

TODO - section on how to batch anneal beads in the kiln after cooling in vermiculite

Finishing

Tips & tricks for how to get beads off mandrel and what to do with them then:

• Take the forceps from the toolbox to grip the mandrel (not the glass bead), and grip the bead with your other hand and rotate
  • take care not to bend the mandrel! this is particularly relevant when using the thin mandrels
• Wash the beads to get the bead release off the inside
  • there are [these things with teeth on] to scratch off the bead release
  • using a shoestring might work, too (for big holes)

Here are some links you may find useful if you want to make your own glass beads: http://www.bullseyeglass.com/methods-ideas/index-of-articles.html http://www.wikihow.com/Make-Your-Own-Glass-Beads-from-Scratch

How to fuse glass together

Please check out http://www.bullseyeglass.com/education/free-videos.html, in particular What is Kiln-glass?, How to Choose a Glass for Kilnforming (especially parts 1-4 and Material Matters: Release Qualities), Glass Cutting, Fusing basics, Preparing Kiln Shelves.

Other uses of the Kiln

The kiln can also be used to fire metal clay or for enamelling. None of the owners so far has had any experience with this. If you would like to try something, please check out safety requirements and send the proposal to Makespace admin for approval.

Other uses of the Torch

• Annealing metal
• Pulling stringer