Striking Glass (Kiln striking)
Pain in the arse
I’m putting it out there, right up front: I hate this glass.
Okay, not really anymore but I felt that way during the testing phase at first. Everything I was doing with Sk2.a turned to bleh. The photo to the right shows the first testing that I did and I wasn’t happy with the results at all, so I knew I was going to be testing it further but I was down to half a rod and hadn’t worked out how to get an intense blue colour. Apparently that is what Sk2.a can do, give you intense blue. Yes, look across to that picture and despair. No intense blue to speak of. For these tests the most I’ve achieved is a pissweak wishy washy blue, the blue green big lentil in the photo is what Sk2.a does over ASK104 Mystic Grey. For the test beads below I changed it up and used Effetre Black instead of Hades and that did make a difference. Sk2.a is a cream coloured glass in the rod and the glass will pretty much stay that way if you cannot strike it in the flame.
Here is a link to the talented work of Kathleen Ritsuko Hosterman, who has managed more than me with Sk2.a on its own. So far the vibe I get from Sk2.a is to hurl it away from me in disgust. You might like it more though or have a lot more success.
Sometime later last week…
I was really fed up with Sk2.a but I decided to tackle it again using Vetrofond Black as my base instead of Hades. I still didn’t have much luck at all (see the top vessel bead in this picture to the right), until I had a brainwave. What if Sk2.a is a booster for other DH glass? Or could be given a boost by using silver leaf?
I tested the silver leaf theory out and hit the jackpot, I could get the blue out of the glass without having to strike the glass in the kiln. You will have to change your kiln settings to strike Sk2.a, increasing the heat and the hold time so that you can strike the glass. This means that you will definitely have to run any beads made with Sk2.a in your kiln on their own.
My way around this is to use the silver leaf to “cheat” a reaction out of the glass to avoid the long kiln strike. The reaction of Sk2.a on silver leaf is varied depending on how you applied the silver to your base bead, what clear glass is used to encase with and how much heat is applied to the bead.
The photograph to the left skews the colour in the beads. Sk2.a is colour shifting under different types of light. The blue is actually much more purple but L.E.D lighting shifts the glass to look blue. This photograph also shows you how the beads look after they’ve been taken out of vermiculite, without being through the kiln. So all of this colour was developed in the flame. I don’t know if they’ll strike more, it is possible that excess silver under the encasing may burn off and change the colour, or they may not change at all. Update: After taking all the photos in different light; personally, I think the colours struck just a tiny bit more, but it’s hard to tell from the photographs.
The information on how to use leaf with Sk2.a isn’t straight forward because this is not a step by step tutorial. That would take a lot of time to write and photograph. Instead I’ve listed down the catalysts for making the beads you see above. This mini tutorial below is photographed in natural daylight. As you can see, bright daylight as well as halogen studio lights causes another colour shift in Sk2.a leaving it looking far more steel grey. I actually really like how Sk2.a shifts in different types of light, I have no idea if this is because of the silver leaf underneath or not as I’ve never been able to successfully kiln strike this glass.
Choice of Glass:
I found that CiM Hades did not go well with Sk2.a (I didn’t bother trying Tuxedo). The beads in the photograph above have been layered with different bases and the best effect was with Vetrofond and Effetre Black. I think CiM blacks hold too much heat and pushes the Sk2.a reaction along too quickly so that you end up with cream-taupe colours instead of blues and purples. Basically, stick with Vetrofond or Effetre black to get the blues and purples out of Sk2.a
Foil or Leaf?
I found this technique worked best with silver leaf. I don’t use foil much in my work but I have thick leaf and when doubled looks like foil. If the leaf is too thick it doesn’t burn off enough to get the blue and purple tones from Sk2.a. So, along with using the right type of black glass, you want to stick with leaf for the purple and blue tones. This is because you will be burning off a little bit of the leaf, before reducing the leaf, applying a thin layer of Sk2.a and striking the glass to blue.
However, if you want the gold reflective metal look and to be able to see the metal inclusion use foil or doubled-up leaf directly on transparent glass without burning it off. You will have to reduce the leaf before layering Sk2.a over it. However, bear in mind that using a thicker application of leaf, it is possible that you will instead get a gold reaction or yellow/orange fume line under the encasement and not gold mirroring if you do not cover the leaf completely with a thin layer of Sk2.a.
If I wanted the silver leaf to remain largely in tact for the reflective gold look, I worked everything extremely cool and lightly burnished in the leaf to avoid any fuming. Then I reduced the silver leaf, then dotted a tiny amount of Sk2.a over the leaf and then smooshed it flat with a brass paddle to cover the leaf with the thinnest layer of Sk2.a, lastly I let it cool, return to heat to strike the Sk2.a, cool lightly and then encase with Effetre Clear.
Sometimes this reaction will go a pale lilac colour (on black) and sometimes it will go bright gold (on light transparent glass) it depends on how long you struck this section of the bead for before encasing. A big dot of Sk2.a over leaf on a black base will give you a very vibrant blue if very slowly melted in, and spread evenly across the leaf.
Burnishing and Burning off:
I burnished my silver for some spots on the beads and for others I didn’t. In places I did not burn off the silver and in others I did. This will be the step that requires the most practice and trial and error. Its better to burnish your leaf in first before encasing in Sk2.a, otherwise it goes brownish gross, particularly if you want to get the blue and purple colours. You can see brownish patches in sections in the photo tutorial above. Its more likely to happen on dark glass.
I found burnishing in and then gently burning off the silver, whilst holding the Sk2.a rod above my bead warming (to catch the silver fumes) worked very well for getting a beautiful bright purple-blue colour. I also found that if I did not burn off the silver a little (and I missed a spot when covering it with Sk2.a) the whole area would turn pale butter coloured and the encasing would be effected as well with a yellow tinge.
Heat vs Cold:
This is one of those techniques that require cooling between each step to get the richest colours. Whether it is for the blue purple effect or for the gold effect. To get the richest blues and purples you need to work cool. To get that metallic gold look to the leaf without the encasing fuming and the silver burning off completely, you need to work cool. Heat, or working the bead too warm will push your reactions to paler colour variations or burn off your silver too much. Admittedly, this is pretty handy to know in a bead, but you want to be able to control the reactions. So work cool and only work warm where you deliberately want paler colours.
Encasing your bead:
I happen to like encasing and a lot of the magic happens when you do encase. Although you can achieve the effects without encasing at all. I found that I was more likely to get blues and purples if I encased with Lauscha and I was more likely to retain any metallic reflective effects if I encased in Effetre. On all of these beads there is a mixture of clear encasing. The colour changes you see in the beads primarily occurred because of heat and the fact that I was testing the difference between CiM Hades, Vetrofond and Effetre Black. Sk2.a is more likely to go yellow on Hades, but encasing Sk2.a hot will also transition it to yellow and then to dirty greeny brown no matter what is used underneath.
Striping and Storming:
In one of the beads you can see a touch of storming effect (paler blue stripes) through some dark blueish glass. This happened in a section of the bead that had a thick layer of burnished (and burned in) leaf that had not been reduced and an application of very hot Sk2.a under a cool thick Effetre Clear encasement. Hot Sk2.a (almost white hot) smeared over leaf produces really interesting effects. I did this by accident and didn’t experiment further, although it has great potential for creating “lightening” as the Sk2.a really develops these white and pale blue jagged bands in a really deep purplish blue background.
Overview of Sk2.a
The challenge of this glass forced me to really think about how to use it. I know there is a bunch of other “sk” coded glass. I am not sure how the other Sk glasses will go with the “silver leaf” technique. There is a photo of my Sk rod in one of the photos above, if your rod looks like this but you’re not getting any reaction out of it, my “expert” Aussie advice is to chuck it over some silver leaf.