The solution found inside the packs is called Sodium (salt) Acetate (vinegar). It is often found as a food flavouring, giving the salt and vinegar taste to potato chips.

Being a food grade saline solution, it is non toxic. However, like all concentrated solutions, care should be taken not to expose sensitive areas such as the eyes or open wounds but otherwise harmless. If for any reason the solution leaks onto clothes, it will feel like it has been starched. A wash in either cold or warm cycle will easily remove the solution. If on furniture, apply a damp cloth with warm water and the crystals will wash away.

Sodium Acetate in super concentrated form is sensitive to friction / vibrations. The flexing of the activator creates friction sufficient to act as a catalyst to form the first crystal. Once the first crystal has formed, it creates a chain reaction - thus the gradual change inside the pack.

This exothermic reaction generates energy - the heat that you feel.

Exposing the crystals to high temperatures (the boiling water) will cause the crystals to revert to liquid form – thus acting to reset the packs.

As the process is a physical change and not a chemical reaction, the exothermic reaction can be “activated” an unlimited number of times.

Similar frictions such as sudden shocks cause by dropping or bumping of the packs can occasionally activate the packs. This is often the cause of the packs activating in transit. Should this be the case, simply reset the packs as per instructions.

Many different types of activators can be used to induce the necessary exothermic reaction.
The activator work by pressing or flexing the circular disc.

The friction generated by the activators and the friction needed to activate the packs will vary with each and every activation thus the number of flexing/bending/pressing will change. As a general norm anywhere between 1-10 activating motions is required to activate the packs with the actual number of motions varying with each activation. So please do not be too concerned should the pack not activate immediately. This is not a sign that the pack is not working or faulty, rather this is an indication that for some reason the friction was inadequate.

In addition, it is more helpful for the activators if you make slow deep motions rather then short rapid ones. The short rapid action MAY NOT generate the necessary friction to activate the packs no matter many motions you make.

The packs reach a safe handling temperature of 54°C and this is the maximum temperature. As the packs cannot physically get beyond this temperature, it is very difficult to ever accidentally burn yourself - the temperature needs to be above 60°C for this to happen. In fact, the self- heating technology is the only heat pack that has a preset safe temperature - one of our core product benefits.

However, as with all heating products, care should always be taken when used - especially if you are intolerant to heat. If the heat is too intense, soften the heat with a towel or use the belts provided in our product range. In some cases, heat amplification effect such as your body temperature being high from exertion or hot weather, the packs being activated whilst it still has some residual heat from the boiling water or putting the pack over heating creams will increase the sensation of the heat - thus caution needs to be exercised under these circumstances.

Further to a safe controlled temperature, each and every time the pack is activated, it will reach the same temperature - it never varies. Thus not only is it safe, it is reliable as well.

The length of the heat varies with each pack. They all reach the same temperatures but the bigger the pack the longer the heat lasts. Heat can last between 20-30 minutes for the Portable to as long as 60-90 minutes on the Seat Warmers. The length of heat is affected by ambient temperature as well as the amount of insulation available.

The plastic casing of the pack is made from Triple A grade industrial PVC - child safe and animal safe. The plastic is able to tolerate up to approximately 106°C, hence not get damaged when boiled - as long as there is sufficient water available.

It can also withstand some weight, however, any sudden pressures such as suddenly sitting on or jumping on the packs can damaged them.

If used properly and carefully, the packs should last about 5 to 10 years. The known record is about 14 years but some customers destroy theirs in 18 months. It is really up to the user.

Sharp instruments will puncture the plastic. Also, the packs are especially vulnerable after just being boiled, as it is soft from the heat. So some care needs to be taken when taking the packs out of the pots.

Finally, when storing the packs, store them in liquid form. Whilst it does not harm the pack whether or not it is stored in either liquid or solid form, the liquid from is recommended. There are two reasons for this. Firstly, it makes sense so that when you need the pack you can use it straight away rather than wait whilst it is being boiled. Secondly, if stored in solid form for long periods, it takes longer to boil back to liquid form.

The Heat Packs can also be used as cold packs.

This is beneficial if you have acute injuries - that is muscle/tendon/ligament tear and sprains within the first 48 hours. When so injured you need to use cold to reduce the swelling then heat to increase blood circulation and increase recovery. Hence, our packs can be used for both.

To use as cold packs, simply place the pack (in liquid form) into the fridge for 1 hour or freezer for 20 minutes (Do NOT Freeze) the pack. If used in solid form it will only stay cold for a short time.

As the salt water has a freezing temperature much lower than the freezer setting, even in the freezer it will not freeze and become ice. Hence, it is always a cold pack not an ice pack.

You can leave the packs in the fridge indefinitely without harming the pack. For active people, we suggest having one in the fridge permanently.

If using as a cold pack, it is generally recommended to use the freezer (for 20 minutes) only to get the pack cold quickly but use the fridge if for long-term storage. Neither adversely affects the packs, however, there are things in the freezer such as frozen meats, icicles or sharp containers that can pierce the packs.