You definitely need to include metallic thread in your list of options. Here are a few secrets we learned along the way:
1. Make sure you are starting out clean. Blow out the bobbin area with your air compressor, and add a drop of oil to the bobbin case (as you normally do for a four hour oiling). Clean the tension spring on the bobbin by sliding a firm piece of paper (we use the edge of the needle envelope) to clean out collected lint.
2. Use a new, oversized needle. For pique knits, since I would use a 75/11 ball point for normal thread, I change to a 80/12 ball point for metallic. On hats or denims, I would go from my normal 75/11 sharp to 80/12 sharp. This allows a little more room for the thread to go through the eye.
3. Reduce tension only to the extent necessary. Metallic doesn't like as much tension (it will break easier than regular thread) but not enough tension is one of the main causes of a bird's nest.
4. Reduce density in the design area that uses metallic thread. The metallic thread is bulkier than normal thread, so it needs less density than regular thread to cover the same area. If you don't reduce density, the metallic will get caught on itself, spear through itself, etc. and cause a bird's nest.
5. Make sure your needle is pointed straight forward. For the total perfectionist, you can point the hole of the needle about 5 degrees off to the right (that's just a TINY little bit to the right). This tends to make a larger loop underneath and gives you a better chance of catching the hook.
6. Slow the machine down a little bit if necessary (last choice). The metallic thread doesn't make as nice a loop as regular thread because of the metallic pieces, so a slower setting gives it more time to catch the hook.
7. Practice doing a tension test (print ten large "I"s in a block font, one in each color, using satin stitches. Note the relative length of bobbin thread exposed underneath on each color. The bobbin should be 1/3 of the total thread underneath. If there is too much bobbin showing on all colors, tighten the bobbin. If there is too much bobbin on one particular color, loosen the top thread. If there is too little bobbin showing on all colors, loosen the bobbin. If there is too little bobbin on one particular color, tighten the top thread.
8. All metallics are not created equal. More expensive thread runs better than cheap thread, and thread is the least expensive part of the embroidery equation. We use Isamet thread from Ackermann for metallic.
If you think it can't be done, relax. It can. Take a look at the Embroidery Business News banner below (click on it for an up-close view). The embroidery is 48" long by 10" high; 323,000 stitches, including silver metallic satin stitches outlining "EMBROIDERY" and gold metallic fill stitch letters for "BUSINESS NEWS".
PS: We won first place in the corporate logo category in EBN's 2000 Punch Bowl Contest for this entry. We don't think they were expecting a banner!