Making Rice Pack Tips ----
Over the course of several rice pack projects I've learned a number of tips and tricks. Just passing the info on to any interested parties here. :)
Get the 2 lb bags of rice from the grocery store, they're the cheapest. If you are making a lot of bags then the 20 lb sacks from an Asian grocery store are the lowest cost.Be very careful with sewing the sections on the packs once you put the rice in, if the machine needle hits a rice piece the wrong way you'll break a needle.* Rice is the most cost effective.
* I've tried popcorn kernels (unpopped popcorn), they hold the heat longer but SMELL like popcorn so I didn't use that.
* I tried buckwheet also, which is mentioned on some sites - don't use it, it smells like horse feed!
* I've tried flax, which works nice and holds the heat a long time but the price of even the bulk flax seed at the health food store went up too high to make it worthwhile.
* Everyone swears by cherry pits, but at $10 a pound, sorry. It's only available online in bulk.
FYI - to avoid insects chewing into them after you have them made and stored, put the finished items in zip lock baggies! I had an unpleasant surprise with the neck warmers I made one year for an event, finding moth caterpillars had chewed into the fabric on two of them. Rice is organic and something will eat it. They were stored in a box up in a closet upstairs for a year, so something got into the box. The larger neck warmer I'd made that I was using regularly never had an issue.
Microwaving it should not be done long - it can start the fabric on fire and scorch the rice. Test each size pack first with 30 second groupings and put the 'warming time' on the label. My wrist ones only needed 30 seconds. My large neck warmer with 2 cups of rice in it took 1 minute 20 seconds. That one was GREAT to heat up right before bed, put in the bed under the covers about waist high and let it be there for 5 minutes. Made a toasty bed to get into. It's good as a foot warmer under the covers too.
Don't use 100% nylon or polyester for the coverings - cotton or cotton blends are best, they won't deteriorate or burn in the microwave.
Flannel also gets 'wet' when microwaved, same as polar fleece. Plus the fabric isn't as strong as cotton.
Sizes -- I did wrist ones with 3 sections. I've done 15" long ones 4" wide for around the neck that work GREAT when you want to warm up on the couch (they fit in the lap too or under the quilt at bedtime, or for your feet to set on). The neck ones can be made in a straight or a curved shape. If you're making an animal form for it, do NOT put button or bead eyes on it, you don't want microwaved beads burning in and branding someone's skin. I've even seen a rice stuffed gardening glove and fake 'arm' done up as zombie parts heating pads.
While they CAN be used as cold packs (in any size) they really don't hold the cold very long. And you have to keep them in a zip lock baggie in the freezer so they don't get damp.
Don't use essential oils - it'll stain the fabric and anything that part of the pack is touching on your clothes.If you want to add in lavender buds, or any other scent like cinnamon sticks, be aware that the smell may be overpowering once the pack is heated. Too many people are allergic so I never used any herbs in mine.
They don't have to be stuffed really bulging tight with rice, leave some room so you can machine sew the opening closed. It lets the item be more form fitting if it can have the rice move around where needed.