DISCLAIMER (of sorts): I don't really do crochet patterns. I like to mostly make it up as I go and use my 'crochet instinct.' (Hey, it works for me.) This means I am probably terrible at giving instructions. I hope they are at least a little bit helpful!
Firstly, I'm assuming you know basic crochet, and in particular, several crocheting techniques:
- crocheting in the round
- DC - double crochet (US term)
- changing colours (if you want to make them stripy)
... if you can't do these things, then I suggest a day trip to YouTube! :) It is one of the best resources on the internet for learning yarn-related things.
To start with, you'll need to salvage a jar. This particular jar used to be full of pesto, and is round. (I'll deal with the issues of square jars later!) I suggest a good, long soak in some warm, soapy water to get rid of all the labels, glue, and old food smell. I used a 4mm hook and some DK acrylic yarn, but there are no particular rules, as you will be adjusting your pattern to the jar and yarn.
Next, using either a magic circle or a good old slipknot (I prefer the magic circle, because it's so seamless and beautiful) you want to chain 3 and then dc into the circle/slipknot around nine or ten times. Do more or less dc as the size of the jar requires. Slip-stitch the first and last dc together, and - voila! You have a circle. :)
Then, continue to crochet in the round using the typical technique to produce a flat circular piece of crochet. i.e.: for the second row, work 2 dc into each dc, for the third row, 1 dc in the first dc, 2 dc in the next dc, for the third, 1 dc in the first 2 dc, then 2 dc in the next dc... and so on. Adjust the frequency of your increases if the circle no longer lies flat. (It should do if you follow this pattern, don't worry!)
Continue doing this for however many rows, depending on the hook size and yarn, until your circle reaches the edge of the bottom of the jar.
After that, it's a very simple case of just continuing in the round with dc, no increases or decreases! I like to making my jar covers striped - I don't bother cutting off the yarn at the end of each colour and just carry it up on the inside, as it won't be seen anyway. (In fact, I don't bother weaving any ends in at all, I just tuck them in and they're pretty much invisible anyway.)
Continue up past the lip of the jar, so that you can tuck the cover over and in, giving the top a nice, deliciously crocheted edge.
Most glass jars I have crocheted covers for get smaller nearer the top - so I like to decrease a few stitches in my later rows to get a snug fit. (Usually not too many - maybe dc2tog after every five stitches.) One I have crocheted over the lip of the jar, I like to finish off by increasing 1 dc every other dc to make a little 'skirt'. This part fans out neatly inside the jar where the circumference increases, and just makes for a better fit for your cover.
Some foodstuffs are very inconsiderate and insist on coming in square jars. My favourite way to get the best shape is to actually start off by making a tiny little granny square for the bottom of the jar. (If you can't do a granny square, please give it a google! If you can dc, you can definitely make grannies, and they are the best thing ever.)
I stop using the granny square technique when it looks like one more row would reach the edge of the jar's bottom, and instead use dc for the last row. The rules are: 1 dc in each dc, 1 dc in each ch1 space, and 3 dc in each ch2 corner space. Then, proceed as with the circular jars. :)
Then, because I'm lazy, I cast off, and shove all the ends in the jar and down the sides of the cover where they can't be seen. Those who are fussier than me are welcome to weave in the ends - but I don't think it's at all aesthetically necessary.
I hope this was understandable and maybe even a little bit helpful! Please let me know if my instructions are unclear and I will do my best to correct it. Happy hooking! ♥