Heat the rice sock in short bursts

You are cold, or something aches, and a heat pack costs money you would rather keep. Many people say the usual homemade answer is a sock or cloth bag of rice heated in the microwave for a minute or two, with the opening tied or sewn shut so the grain stays in. Some people say it is cheap and can be reused. What a shop-bought pack has and this one does not is a label with a heating time, and the burns and fires in the warnings below start there.

Make a heat pack from clean cotton and dry uncooked rice, heat it in short bursts and check it with your hand before it touches your skin, and keep it away from bedding and from anyone who cannot feel heat or cannot move it.

If you cannot feel heat well, cannot move it yourself, or want it to warm a bed, this page is not for you as written. The end of it says why.

Make it

The sock matters more than it looks. Some people say it should be a natural fibre such as cotton, because nylon, polyester and plastic elastic can melt in the microwave; some people warn of melting and fire from synthetic fabric. One person says polyester also goes brittle with repeated heating and so does not last. Some people warn that metal thread in a sock is a fire risk. One person pointed out that elastic does not melt, while others say to avoid it; a sock with no elastic, or a small cloth bag you sew yourself, settles the question at no cost. Some people say a leg cut from old jeans is another option, and one person says denim lasts longer than a sock.

Some people say to wash the sock first, to avoid smell and mess.

Many people say the rice must be uncooked and dry; cooked rice is not suitable. One person warns that instant rice may start a fire. Many people say to close the opening by tying or sewing it, and some people say sewing it shut works as well as a knot.

Heat it, with no label to follow

Many people say a minute or two is usual, but with no label to follow, start at 30 seconds and add short bursts, and some people say to heat in short bursts, around a minute at a time, and to lower the power if the microwave is strong. The figures people give are small: one person says 30 to 40 seconds for a cup of rice, and another about 45 seconds for an ankle sock. A medical paper on burns from wheat bags measured how hot they get. Two of the three bags heated as the label said reached about 57°C (135°F); in a 1,000 watt microwave, about 61 to 63°C (142 to 146°F); and when reheated, about 69 to 70°C (157°F). Those were shop-bought bags, and the paper called for labels with heating times for microwaves of different power. That is why heating in short bursts, as some people do, makes sense for a pack with no label: you add time instead of guessing it.

Stay by the microwave. The fire service says not to leave it unattended, and not to heat a bag for more than 3 minutes. Some people warn that dry grain can scorch if it is heated too long, and one person says a scorched pack smells like burnt popcorn and is spoiled; others say they have used one for years without trouble. The fire service advice is on the cautious side of that split, because the fire it describes comes from overheating. Stop the microwave at once if it sparks, crackles or smokes. If it smells burnt or charred, let it cool in the kitchen sink and throw it away.

When it comes out, leave it a minute. Some people warn that the steam inside is very hot. One person says it should feel hot to the touch but not burning, and some people say to check the temperature carefully. A layer of clothing or a towel between the sock and your skin is the cheap way to follow the advice in NHS hospital foot-care leaflets, which say not to put a heat pad directly on the skin when feeling is reduced. One person says the sock sticks to skin and clothing when it is hot.

Then let it cool completely. Greater Manchester Fire and Rescue Service says to cool a bag on a non-combustible surface, such as the kitchen sink, and not to reheat it until it is fully cool, about 2 hours. One person reheats in shorter bursts once it has cooled a little; the fire service advice is the other way, and a second pack, or a wait, costs nothing next to a burn. One person says to let the sock dry out after use and to shuffle the rice about now and then, and one person warns that mice may be drawn to these packs.

One person’s pack stayed cold, and the microwave’s power setting may be why. If yours does not heat after a short burst, add another burst rather than a long one.

What it is good for, and what it is not

One person says a rice pack moulds to the knee, shoulder or neck, and prefers it to an electric pad for the weight and the shape. Some people say it costs less than a shop-bought pack. One person worked out that the electricity for heating a bag and for running an electric blanket differs by less than ten cents, so the saving is in the sock, not the power.

Some people prefer a rubber hot water bottle because it holds its heat much longer, through to the morning, and the water has a second use around the house. What separates the two is how long you need the heat: a grain pack suits a short spell of warmth for a sore spot or cold hands and feet, and a bottle suits a long night. The fire service advice is that the grain pack is not for the night.

Some people say a microwaved pack is safer than an electric one for older people or children, because it loses heat gradually and has no wiring that can fail. It has no wiring, but the fire service and the burn paper describe a pack that burns skin and, in the wrong place, catches fire. Some people also say worn wiring in an electric blanket has caused house fires; this page does not cover electric blankets.

Who this page is not for

If you have lost feeling in your skin, as can happen with nerve damage from diabetes, spinal injury or spina bifida, the paper on burns found that people with impaired feeling were at particular risk, because heat that would make another person pull away does not warn them. A pack is not for you until a doctor or nurse has said how to use one.

If you cannot move it off your body yourself, for example because of limited mobility, the same reasoning applies. One person warns that someone who cannot move it may not be able to remove it when it becomes too hot.

If you want to warm a bed, or to sleep with it, the fire service says not to use it as a bed warmer.

If you have no microwave, this page does not cover heating one in an oven or on a stove. And if it is for a baby or small child, this page does not cover that.

The label a shop-bought pack carries is the part this one leaves to you: the time, the cool-down and the check.