I love participating in art installations (Mini-me and redsweaters.org were a couple of my favorite contributions). So when I discovered The Perovskite Project at the University of Surrey in England. I knew I HAD to participate. I rummaged through my stash, found the required yellow and blue yarn, and immediately started.
The pattern calls for a dk weight yarn but the only blue and yellow yarn I found in the stash was Red Heart Super Saver - worsted weight, so right off the bat I was going to have to do gauge adjustments on both the octahedron and the central atom.
My Notes for the central atom :
Crochet hook: 3.5mm / E
Yarn: Red Heart Super Saver - Bright Yellow
The pattern is written using English crochet terminology. However, the only adjustment needed was to translate double crochet as single crochet.
I kept the same crochet hook size (rather than size up for the yarn). It produced a firmer fabric which should hold the shape well.
I worked increase rows until I had 24 stitches (through round 5). I got a measurement slightly over 4 cm across.
I used the invisible decrease to work the last half of the sphere. The invisible decrease is a great technique and makes an incredible difference in how crocheted balls look. You can find a good tutorial about it here
at Planet June.
My Notes for knitting the octahedron:
Knitting needles: size 4
Yarn: Red Heart Super Saver - Royal
Unfortunately, there was no way I was going to get 10 stitches to 3.5 cm with the worsted weight yarn and no matter how I tweaked the pattern I couldn't get an equilateral triangle by increasing from a point. In a last ditch effort, I tried getting one by starting with a base and decreasing to a point. Voilà! I could finally make equilateral triangles a little bigger than 7 cm.
The pattern that worked for me (and hopefully will help someone else)
Stitch definitions:
ssk (slip, slip, knit) = Slip the first stitch as if to knit, slip the second stitch as if to knit, then slide the left-hand needle into the front part of both stitches and knit them together.
p2tog (purl 2 together) = Insert the needle through two loops, like you were purling a single stitch. Purl the 2 stitches together as if they were 1 stitch.
Cast on 14 sts
Row 1: Purl (I purl this row because I use the long-tail cast on, which is essentially knitting the first row)
Row 2: Ssk, knit across.
Row 3: P2tog, purl across.
Row 4: Knit.
Row 5: Purl.
Row 6: Ssk, knit across.
Row 7: P2tog, purl across.
Repeat rows 6 and 7 until you have one stitch. Finish off.
My Notes for assembling the octahedron:
Using cardboard not only "blocks" the triangles to the right size but it provides the shape as well. I used a fairly lightweight cardboard from a frozen pizza box. The cardboard was flexible enough that I could poke a sewing needle through and tack down the three corners of the knitted triangle but it was firm enough to keep its shape without bending.
The cardboard triangles are 7cm and when I stitch them to the knitted pieces I'm centering and stretching the knitted pieces to leave space to sew a seam (see above photo).
The instructions state: "create defined edges by sewing the pieces wrong side together with the joining stitches on the outside of the piece". I think this means to put the seam allowance on the outside of the octahedron but I couldn't create a nice looking outside ridge when stitching this way (maybe because I knit the squares from the base down??) I figure the important feature is to have defined edges and I wasn't having any problem with that because the cardboard and the inside seam allowances created a clear shape.
In fact, I was getting such great structure that I debated with myself about stuffing it. I did decide on stuffing because these pieces will be doing some traveling and the stuffing will provide a cushion.
I have until August 31 to get a bunch of these knitted, crocheted and shipped off to England. I'll take more photos and make updates along the way. I'll also post links to the final installation when they're available.
Hmmmm, these colors are also the colors of
Boston Strong. I may have to find a project for that as well!
Update:The knit Perovskite crystal structure has been completed! Information about the finished project can be found at the University of Surrey on the
About the Project page and at Facebook on
The Perovskite Project page.
