This would be a good time to share some thoughts and experiences I've had with using these two different types of knitting needles, with the idea that maybe it will help others to avoid some problems.
Some background: I've been knitting, off and on, since the 1960's, dropped it for a long time, but with the inspiration of all that is available on the internet, I picked it up with enthusiasm 3 years ago, when I began knitting socks. At the time I only had metal needles, and it was a struggle to learn how to use double-pointed needles (dpn, for short), because they kept slipping out of the stitches as I worked them around the sock body. Somewhere I learned about bamboo needles, and took a chance on using them instead. Eventually they became my favorites for almost all of my knitting, however they did have drawbacks; the tension was looser, the stitch didn't slide off the needle as easily as it was being formed the same way it did with metal, and the work was slower because of it. So I thought I would again try metal, specifically the somewhat newer, slicker needles available now. So below these are some of the things I've found out about using the different needles.
1. As mentioned above, the gauge/tension of the stitches was quite a bit different comparing metal to bamboo. I started a shawl with fingering-weight yarn and size 3 metal circular needle with a very slick needle surface. My stitches were close together and small. After several inches I switched to a bamboo circular of the same size, and after a few inches of using the bamboo needles, the stitches were loose and larger. It isn't very noticeable, but it surprised me that there would be that much difference in stitch size with the same size needle. Once again this illustrates the importance of gauge and making a test swatch with knitting.
2. Muscle/joint pain: In a previous blog I wrote about knitting toe-up socks, with the peacock blue/turquise socks. With those socks I used metal needles throughout, used the same number of stitches as for socks I had previously knitted, but when finished they were smaller than socks made with the bamboos. But I also had quite a bit of wrist and finger pain, and swollen joints all the way up into my shoulders, so much so that I was limited to the amount of time that I could work on the socks. I didn't connect the pain to using the metal needles, until I started working on the shawl mentioned in #1. When I worked on it with the metal needles, everything hurt; when I switched to the bamboos, the pain went away, and knitting was fun again.
3. Eye fatique: the light glinting on the slick metal surface of the metal needles really tired out my eyes and after an hour or two of knitting, I would have to set it down to get my eyes to rest and re-focus. The bamboo needles didn't give me problems like this.
Now some tips on the care and feeding of bamboo needles.
1. When I first got my bamboo needles they seemed dry to the touch, like raw, unfinished wood feels. So, thinking along the lines of keeping wood furniture waxed and polished to preserve it, I began experimenting with one set of needles, trying various waxes and oils on the needles to see what it would do to them:
a. cold cream - I know it sounds weird, but basic cold cream is a mixture of oil, beeswax and water; I smoothed this into the bamboo needle, let it dry and then rubbed it with paper toweling, cotton rags and waxed paper to see what it would do. It worked very well, and it was right at hand, so I grabbed it to try.
b. olive oil - worked okay and didn't leave an oily residue, but cold cream worked better.
c. mayonnaise - this worked good too, but not as handy as the cold cream
d. candle wax - didn't do much.
My bamboo needles now have a nice polished feel to them, which helps in moving the yarn along on the needle as it is worked. I feel that the oils and waxes also helped to keep the bamboo flexible and stronger than they would otherwise be in their original state as dry and unpolished. The natural oils from the wool yarn also help in keeping the needles polished.
I hope these tips help with enjoying knitting. They have for me.